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SCIENTIFIC FACTS of POTWhile much research has been done to produce this site, we're very new and will be adding a tremendous amount to it over the coming weeks and months. Please visit regularly to keep yourself educated!
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Studies Marijuana Fights: Heart Disease Cancer Diabetes Osteoporosis Alzheimer's Liver Disease Epilepsy Skin Allergies Post Traumatic Stress Disorder Anxiety and Depression and is also Neuroprotective and Causes Neurogenesis (brain cell growth) Why is this scientific evidence any better than hearsay? Aren't these scientists always disagreeing anyway? It's all just fashion... It is unfortunate that many laymen still have this horrific misunderstanding of science after graduating from grade school. Science is the pursuit of truth that lies outside of human interference, opinion and bias. Everything about science is designed to eliminate the adulteration of human perception. Is it perfect and without mistake? No, but it is tens of thousands of times more reliable than anything else. Humanity has not yet learned everything in the universe but with the help of science we are slowly making our way there. Wihtout the strict processes, examination and re-examination of data that is required for real science, we would be forever stuck in the dark ages ruled over by tyranny or anarchy. We would still be blundering in the dark and dying by the age of thirty. When I hear words like the question above uttered, I nearly want to weep for what it portends. Science as a community does it's best to find the truth and is sometimes wrong anyway. It's rare and usually quite a small thing but when we discover we are wrong we immediately change. Every single person in the scientific comunity would love to find where accepted science is wrong because of the pride and recognition that comes with such a discovery. Millions of people all diligently looking for any little corner where we might be wrong with great reward to be had if they find it. Consider the opposite: millions of people all trying to defend a concept's rightness with death being the punishment for mentioning a possible flaw. What do each of these "studies" represent? When a research department at some university wishes to conduct a study they must put together a very comprehensive plan for how it will be accomplished; what it will prove and how that information will be valuable. This proposal is then given to number of institutions with a vested interest in the advancement of knowledge and they will not just hand over a gigantic sum of money to a bunch of unprepared or unprofessional amatuers. Each study below represents tens of thousands of dollars and untold man hours. Each study is a huge investment of passion and a reflection upon each of the researchers, but the pressure to perform has only just started once the grant has come through. If the results of the study are not published in a reputable peer-reviewed journal, all of the time and money is utterly wasted and thrown in the trash because without publication, the scientific community will reject any findings of the study. This kind of gigantic waste can lay waste to a research department and the careers of all the researchers involved. Needless to say, it is critical for the study to pass the peer-review process. The peer-review process requirement of publication in a journal is put in place as a way for other professionals in the same area of science to review the processes undertaken by the study. These reviewers assure not only that there is not blatent twisting of facts but also that experimenter bias is accounted for and that pre-concieved notions can have not even an accidental effect on the outcome of the study. They also assure that the conclusions drawn from the data do not include anything presumtuous. When only one study points to a particular new understanding it is a very significant consideration for being truth. When multiple studies point to the same thing, it is as close to absolute, factual, unbiased, immutable, truth as humanity is or will ever be capable of grasping. Helpful notes for laymen to understand the below studies: The brain has many different chemicals messages it passes between cells. When a chemical is sent, it is received by receptors. This is referred to as agonism. Some other chemicals can block the receptors so that the chemical signals cannot be received for a time. This is called antagonism. When a specific receptor type is agonised repeatedly, the body reduces the number of receptors for that chemical so that the same amount of chemical has less effect. It is a sort of "I got it already!" mechanism and it is called down-regulation. When the body needs a cell to receive more of a certain signal it expresses more of that receptor on the cell so that the same amount of chemical message being sent has more of an effect and this is called up-regulation. The down-regulation mechanism is familiar to most everyone as having "tolerance". For instance, if you have a large alcohol tolerance it is because the exposure to it has caused your body to down-regulate the chemical message receivers for the chemicals alcohol stimulates in the brain. Once the chemical stimulator (alcohol) is gone and chemical transmission levels drop to normal levels, the chemical signal that is being sent at the same strength as before is no longer received as strongly. Down-regulation is one component of addiction but is certainly not always negative and not always indicative of addiction. For instance: Liver fibroids, which are the beginning stage of cirrhosis, are abnormal cells which express a larger than normal number of CB2 receptors. When these receptors are agonised (signalled) to some particular level, the cell enters a self-destruct state and dies. This is the mechanism by which cannabis cures the liver. CB1 agonism of nearby healthy cells is necessary however to cause cells to divide and replace the lost cells. Because CB1 causes cell growth, it also tells abnormal cells to grow and without CB2 there simultaneously to tell them to die, it could cause a worsening of the condition. Natural cannabis contains both CB1 and CB2 agonists but some studies may use synthetic chemicals which only ignorantly push one button without pushing the other. All chemical systems within the body exibit cyclical balancing systems and tight inter-chemical relationships which are unfortunately ignored in some studies or unknown to the researchers at the time. This is an unfortunate side-effect of hyper-specialization of researchers. Recent inter-disciplinary efforts and examination of studies have begun to reveal the mechanisms behind what previously seemed conflicting information. For instance, in the case of the liver fibroids, the neurogenesis effect of CB1 could analagously show the purpose of CB1 in liver disease and its dependance upon CB2. Further research notes for laymen and professionals: In the search for medicines that are sponsored by pharmaceutical companies, it is an unfortunate fact that it is more beneficial for them to find a patch than a cure. One or more pills a day for the rest of your life is more profitable than a once a week treatment that ends in a month. To this end let me point out an obvious mechanism that is not purposeful: Short-sightedness and short-term fixes. In the process of dealing with disease, the body must go through a process of increasing and decreasing chemicals. This means that there are some chemicals that increase others and there are some that decrease others. Without a balancing system the body would fly into an enless loop of trying to deal with an issue and never stop. Every system has a homeostasis which is meant to temporarily shift in one direction or another. For instance: Chem1 increases release of chem2 and chem2 decreases the release of chem1. This is oversimplified because there are things such as thresholds which play a role in timing etc. The point I wish to exibit is that if a cell expresses additional receptors it may be a sign of disease that can be mistaken to be a cause of disease. This type of misunderstanding is seen throughout research and is a major cause of conflicting study results. For instance: Expression of the 5ht2a receptor in the brain is a mild predictive factor in mental illness. Agonism of this receptor causes the patient to exibit more schizophrenic behaviors. Upon first examination it would seem that antagonism of this receptor would be the best course of action in a schizophrenic patient and this is typically the course suggested by researchers. However, agonism of this receptor also causes other natural corrective systems, such as oxytocin to begin working and eventually causes a chemical signal that causes a decrease in the release of natural 5ht2a agonists by the brain. Acute or chronic agonism of the receptor can also cause it to down-regulate. Antagonism and down-regulation are functionally the same in the short term. If the receptors are blocked you receive less signal, if there are less receptors, you recieve less signal. Unfortunately, short-sightedness and quick-fix mentality can lead to un-intended side-effects. In the above example along with the temporary undesirable effects, there are a number of corrective systems that are kicked off by agonism of receptor. While it may be obvious to an inter-disciplinary researcher such as myself that stimulating the body to fix itself is better than ignorantly trying to directly meddle in the unknown, most hyper-specialized researchers are utterly ignorant of this principle. Another example of this phenomenon is antacid dependance: We all are aware of the condition where people begin eating antacids by the handful and they continue to get worse but few are aware of why this happens. Excessive acid in the stomach is often caused by the body attempting to return to homeostasis. When the PH of the rest of the body is too alkaline, the stomach can create additional acid which can be absorbed and distributed into the rest of the body thereby lowering the PH to a normal level. Some antacids are pure alkaline. Upon taking this alkaline substance, the acid in the stomach is neutralized but, typically, there is more alkaline than the acid in the stomach so the antacid user imediately feels relief but compounds the process as they absorb extra alkalinity and cause the initial problem to become worse. So the cycle begins again. If they had instead toughed it out or even eaten more acidic foods, homeostasis would have returned and less acid would be produced by their stomach. If you do your own research please keep these things in mind during the process Heart
Disease General paper endocannabinoids
have been proposed as novel possible hypotensive agents, and
involved in acute myocardial infarction and cirrhosis. In addition,
a protective role described in ischemia. Cardioprotective role of CB2 cardioprotection against myocardial ischaemia by
CB2 --- Cannabinoids and cardiovascular disease: the outlook for clinical treatments.Ashton JC, Smith PF. Department of Pharmacology and Toxicology, University of Otago, Dunedin, New Zealand. john.ashton@stonebow.otago.ac.nz Cannabinoid drugs exert their effects primarily through activation of cannabinoid CB1 and CB2 receptors. Both CB1 and CB2 receptors have been implicated in a number of cardiovascular processes, including vasodilation, cardiac protection, modulation of the baroreceptor reflex in the control of systolic blood pressure, and inhibition of endothelial inflammation and the progress of atherosclerosis in a murine model. These effects are mainly mediated through central and peripheral nervous system CB1 receptors, vascular CB1 receptors and immune cell CB2 receptors. Relevant cellular effects include: the inhibition of neurotransmitter release in the nucleus tractus solitarius and in peripheral adrenergic neurons; regulation of NOS activity in vascular beds; inhibition of vascular smooth muscle cell excitability; regulation of endothelial cell migration and proliferation; and effects on immune cell proliferation, activation, and inflammatory functions. We review the pre-clinical evidence for beneficial effects of cannabinoid drugs in a range of vascular and cardiovascular pathologies. We also discuss the clinically relevant potential of cannabinoids. --- Endocannabinoids have been implicated in protective effects in the heart and brain, but the mechanism of possible infarct-size-reducing effects remains controversial. Using a model of delayed preconditioning (PC), rats received the nitric oxide (NO) donor nitroglycerin (0.15 mg/h/kg) for 24 hours via transdermal application. Two days later, rat isolated perfused hearts were subjected to global, no-flow ischemia (20 min), and reperfusion (120 min). Cannabinoid receptor antagonists were given before no-flow throughout the protocol. Endocannabinoids were detected by liquid chromatography and mass spectrometry. NO-induced PC reduced the left ventricular infarct size from 40.9 +/- 3.9% to 27.5 +/- 3.8% (P < 0.05). Treatment with the specific CB1 cannabinoid receptor antagonist AM-251 (0.3 microM) prevented the protective effect of PC on infarct size (40.2 +/- 4.7%, P > 0.05 vs. controls). On the contrary, the specific CB2 receptor antagonist AM-630 (0.3 microM) did not alter infarct size (31.6 +/- 6.3%, P > 0.05 vs. PC alone). Recovery of left ventricular developed pressure and coronary flow was incomplete in control and NO-pretreated hearts and not consistently altered by cannabinoid receptor antagonists. PC increased the heart tissue content of the endocannabinoid 2-arachidonylglycerol (2-AG) from 4.6 +/- 1.0 nmol/g in controls to 12.0 +/- 2.1 nmol/g (P < 0.05). Tissue levels of the endocannabinoid arachidonylethanolamide (anandamide) remained unchanged (19.8 +/- 3.9 pmol/g vs. 19.5 +/- 4.8 pmol/g). 2-AG (1 microM) or its metabolically stable derivative noladinether (0.1 microM), given 30 minutes before ischemia/reperfusion in unpreconditioned hearts, mimicked the cardioprotective effects of PC and reduced infarct size.We conclude that delayed PC through transdermal nitroglycerin application increases the production of the endocannabinoid 2-AG which elicits protective effects against myocardial infarction via CB1 cannabinoid receptors which represents one new mechanism of NO-mediated PC. --- Delta-9-tetrahydrocannabinol (THC), the
major active component of marijuana, has a beneficial effect on the
cardiovascular system during stress conditions, but the defence
mechanism is still unclear. The present study was designed to
investigate the central (CB1) and the peripheral (CB2) cannabinoid
receptor expression in neonatal cardiomyoctes and possible function
in the cardioprotection of THC from hypoxia. Pre-treatment of
cardiomyocytes that were grown in vitro with 0.1 - 10 microM THC for
24 h prevented hypoxia-induced lactate dehydrogenase (LDH) leakage
and preserved the morphological distribution of alpha-sarcomeric
actin. The antagonist for the CB2 (10 microM), but not CB1 receptor
antagonist (10 microM) abolished the protective effect of THC. In
agreement with these results using RT-PCR, it was shown that
neonatal cardiac cells express CB2, but not CB1 receptors.
Involvement of NO in the signal transduction pathway activated by
THC through CB2 was examined. It was found that THC induces nitric
oxide (NO) production by induction of NO synthase (iNOS) via CB2
receptors. L-NAME (NOS inhibitor, 100 microM) prevented the
cardioprotection provided by THC. Taken together, our findings
suggest that THC protects cardiac cells against hypoxia via CB2
receptor activation by induction of NO production. An NO mechanism
occurs also in the classical pre-conditioning process; therefore,
THC probably pre-trains the cardiomyocytes to hypoxic
conditions. http://www.ncbi.nlm.nih.gov/pubmed/15451779?ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum BACKGROUND: Endocannabinoids are novel lipid mediators with hypotensive and cardiodepressor activity. Here, we examined the possible role of the endocannabinergic system in cardiovascular regulation in hypertension. METHODS AND RESULTS: In spontaneously hypertensive rats (SHR), cannabinoid-1 receptor (CB1) antagonists increase blood pressure and left ventricular contractile performance. Conversely, preventing the degradation of the endocannabinoid anandamide by an inhibitor of fatty acid amidohydrolase reduces blood pressure, cardiac contractility, and vascular resistance to levels in normotensive rats, and these effects are prevented by CB1 antagonists. Similar changes are observed in 2 additional models of hypertension, whereas in normotensive control rats, the same parameters remain unaffected by any of these treatments. CB1 agonists lower blood pressure much more in SHR than in normotensive Wistar-Kyoto rats, and the expression of CB1 is increased in heart and aortic endothelium of SHR compared with Wistar-Kyoto rats. CONCLUSIONS: We conclude that endocannabinoids tonically suppress cardiac contractility in hypertension and that enhancing the CB1-mediated cardiodepressor and vasodilator effects of endogenous anandamide by blocking its hydrolysis can normalize blood pressure. Targeting the endocannabinoid system offers novel therapeutic strategies in the treatment of hypertension. --- http://www.ncbi.nlm.nih.gov/pubmed/12136723?ordinalpos=8&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
We have found that intravenous administration of cannabinoid receptor (CB) agonist HU-210 (0.05 mg/kg), increases cardiac resistance against arrhythmogenic effect of epinephrine, aconitine, coronary artery occlusion and reperfusion in rats. Pretreatment with CB2-receptor antagonist, SR144528 (1 mg/kg), completely abolished the antiarrhythmic effect of HU-210. However this effect of HU-210 was not attenuated by pretreatment with CB1-receptor antagonist, SR141716A (3 mg/kg). We also found that HU-210 (0.05 mg/kg) decreased the relationship between infarction size and area of ischemia. It is concluded that CB2 receptor stimulation promotes an increase in the cardiac resistance against arrhythmogenic influences and probably increases myocardial tolerance of both ischemic and reperfusion damages in rats.
http://www.bentham.org/mrmc/contabs/mrmc5-10.htm#6 Time-lapse microscopy of human lung cancer (H460) cells showed that the endogenous cannabinoid anandamide (AEA), the phyto-cannabinoid Delta-9-tetrahydrocannabinol (THC) and a synthetic cannabinoid HU 210 all caused morphological changes characteristic of apoptosis. Janus green assays of H460 cell viability showed that AEA and THC caused significant increases in OD 595 nm at lower concentrations (10-50 microM) and significant decreases at 100 microM, whilst HU 210 caused significant decreases at all concentrations. In rat heart mitochondria, all three ligands caused significant decreases in oxygen consumption and mitochondrial membrane potential. THC and HU 210 caused significant increases in mitochondrial hydrogen peroxide production, whereas AEA was without significant effect. All three ligands induced biphasic changes in either mitochondrial complex I activity and/or mitochondrial complex II-III activity. These data demonstrate that AEA, THC, and HU 210 are all able to cause changes in integrated mitochondrial function, directly, in the absence of cannabinoid receptors. --- http://www.ncbi.nlm.nih.gov/pubmed/16078104?ordinalpos=10&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum McAllister SD, Chan C, Taft RJ, Luu T, Abood ME, Moore DH, Aldape K, Yount G. California Pacific Medical Center Research Institute, 475 Brannan St., Suite 220, San Francisco, CA 94107, USA. mcallis@sutterhealth.org Normal tissue toxicity limits the efficacy of current treatment modalities for glioblastoma multiforme (GBM). We evaluated the influence of cannabinoids on cell proliferation, death, and morphology of human GBM cell lines and in primary human glial cultures, the normal cells from which GBM tumors arise. The influence of a plant derived cannabinoid agonist, Delta(9)-tetrahydrocannabinol Delta(9)-THC), and a potent synthetic cannabinoid agonist, WIN 55,212-2, were compared using time lapse microscopy. We discovered that Delta(9)-THC decreases cell proliferation and increases cell death of human GBM cells more rapidly than WIN 55,212-2. Delta(9)-THC was also more potent at inhibiting the proliferation of GBM cells compared to WIN 55,212-2. The effects of Delta(9)-THC and WIN 55,212-2 on the GBM cells were partially the result of cannabinoid receptor activation. The same concentration of Delta(9)-THC that significantly inhibits proliferation and increases death of human GBM cells has no significant impact on human primary glial cultures. Evidence of selective efficacy with WIN 55,212-2 was also observed but the selectivity was less profound, and the synthetic agonist produced a greater disruption of normal cell morphology compared to Delta(9)-THC. --- http://www.ncbi.nlm.nih.gov/pubmed/16250836?ordinalpos=6&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum Marijuana has been used in medicine for millennia, but it was not until 1964 that ?9-tetrahydrocannabinol (?9-THC), its major psychoactive component, was isolated in pure form and its structure was elucidated. Shortly thereafter it was synthesized and became readily available. However, it took another decade until the first report on its antineoplastic activity appeared. In 1975, Munson discovered that cannabinoids suppress Lewis lung carcinoma cell growth. The mechanism of this action was shown to be inhibition of DNA synthesis. Antiproliferative action on some other cancer cells was also found. In spite of the promising results from these early studies, further investigations in this area were not reported until a few years ago, when almost simultaneously two groups initiated research on the antiproliferative effects of cannabinoids on cancer cells: Di Marzo's group found that cannabinoids inhibit breast cancer cell proliferation, and Guzman's group found that cannabinoids inhibit the growth of C6 glioma cell. Other groups also started work in this field, and today, a wide array of cancer cell lines that are affected is known, and some mechanisms involved have been elucidated. ---
--- Endogenous arachidonic acid metabolites with properties similar to compounds of Cannabis sativa Linnaeus, the so-called endocannabinoids, have effects on various types of cancer. Although endocannabinoids and synthetic cannabinoids may have pro-proliferative effects, predominantly inhibitory effects on tumor growth, angiogenesis, migration and metastasis have been described. Remarkably, these effects may be selective for the cancer cells, while normal cells and tissues are spared. Such apparent tumor cell selectivity makes the endocannabinoid system an attractive potential target for cancer therapy. In this review we discuss various means by which the endocannabinoid system may be targeted in cancer and the current knowledge considering the regulation of the endocannabinoid system in malignancy. --- Cannabinoids are a class of pharmacologic compounds that offer potential applications as antitumor drugs, based on the ability of some members of this class to limit inflammation, cell proliferation, and cell survival. In particular, emerging evidence suggests that agonists of cannabinoid receptors expressed by tumor cells may offer a novel strategy to treat cancer. Here, we review recent work that raises interest in the development and exploration of potent, nontoxic, and nonhabit forming cannabinoids for cancer therapy. --- http://www.ncbi.nlm.nih.gov/pubmed/18159069?ordinalpos=8&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum BACKGROUND: Cannabinoids, in addition to having palliative benefits in cancer therapy, have been associated with anticarcinogenic effects. Although the antiproliferative activities of cannabinoids have been intensively investigated, little is known about their effects on tumor invasion. METHODS: Matrigel-coated and uncoated Boyden chambers were used to quantify invasiveness and migration, respectively, of human cervical cancer (HeLa) cells that had been treated with cannabinoids (the stable anandamide analog R(+)-methanandamide [MA] and the phytocannabinoid delta9-tetrahydrocannabinol [THC]) in the presence or absence of antagonists of the CB1 or CB2 cannabinoid receptors or of transient receptor potential vanilloid 1 (TRPV1) or inhibitors of p38 or p42/44 mitogen-activated protein kinase (MAPK) pathways. Reverse transcriptase-polymerase chain reaction (RT-PCR) and immunoblotting were used to assess the influence of cannabinoids on the expression of matrix metalloproteinases (MMPs) and endogenous tissue inhibitors of MMPs (TIMPs). The role of TIMP-1 in the anti-invasive action of cannabinoids was analyzed by transfecting HeLa, human cervical carcinoma (C33A), or human lung carcinoma cells (A549) cells with siRNA targeting TIMP-1. All statistical tests were two-sided. RESULTS: Without modifying migration, MA and THC caused a time- and concentration-dependent suppression of HeLa cell invasion through Matrigel that was accompanied by increased expression of TIMP-1. At the lowest concentrations tested, MA (0.1 microM) and THC (0.01 microM) led to a decrease in invasion (normalized to that observed with vehicle-treated cells) of 61.5% (95% CI = 38.7% to 84.3%, P < .001) and 68.1% (95% CI = 31.5% to 104.8%, P = .0039), respectively. The stimulation of TIMP-1 expression and suppression of cell invasion were reversed by pretreatment of cells with antagonists to CB1 or CB2 receptors, with inhibitors of MAPKs, or, in the case of MA, with an antagonist to TRPV1. Knockdown of cannabinoid-induced TIMP-1 expression by siRNA led to a reversal of the cannabinoid-elicited decrease in tumor cell invasiveness in HeLa, A549, and C33A cells. CONCLUSION: Increased expression of TIMP-1 mediates an anti-invasive effect of cannabinoids. Cannabinoids may therefore offer a therapeutic option in the treatment of highly invasive cancers.
Cannabinoids exert antiproliferative properties in a variety of malignant tumors, including pancreatic ductal adenocarcinoma (PDAC). In our study, we quantitatively evaluated the immunoreactivity for cannabinoid-1 (CB1) and cannabinoid-2 (CB2) receptors as well as for the endocannabinoid metabolizing enzymes fatty acid amide hydrolase (FAAH) and monoacyl glycerol lipase (MGLL). Furthermore, quantitative real-time RT-PCR for CB1, CB2, FAAH and MGLL in normal pancreas and pancreatic cancer tissues was performed. Levels of endocannabinoids were determined by liquid chromatography/mass spectrometry. Immunoreactivity scores and QRT-PCR expression levels were correlated with the clinico-pathological (TNM, survival, pain) status of the patients. Evaluation of endocannabinoid levels revealed that these remained unchanged in PDAC compared to the normal pancreas. Patients with high CB1 receptor levels in enlarged nerves in PDAC had a lower combined pain score (intensity, frequency, duration; p = 0.012). There was a significant relationship between low CB1 receptor immunoreactivity or mRNA expression levels (p = 0.0011 and p = 0.026, respectively), or high FAAH and MGLL cancer cell immunoreactivity (p = 0.036 and p = 0.017, respectively) and longer survival of PDAC patients. These results are underlined by a significant correlation of high pain scores and increased survival (p = 0.0343). CB2 receptor immunoreactivity, CB2 receptor, FAAH and MGLL mRNA expression levels did not correlate with survival. Therefore, changes in the levels of endocannabinoid metabolizing enzymes and cannabinoid receptors on pancreatic cancer cells may affect prognosis and pain status of PDAC patients. (c) 2007 Wiley-Liss, Inc. --- http://www.ncbi.nlm.nih.gov/pubmed/17943631?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum Objective. Cannabinoids are a class of
compounds that have the ability to activate two specific receptor
subtypes, the cannabinoid CB1 and CB2 receptors. CB1 receptor is a
G-protein-coupled receptor that is linked to the signal transduction
pathways. The cumulative effects of this receptor have important
implications in the control of cell survival and cell death having
the potential to regulate tumor cell growth. In this connection,
interest has been focused on factors such as sex steroid hormones,
which regulate CB1 receptor expression. The aim of this study was to
investigate the effects of 17beta-estradiol exposure on the CB1
receptor gene and its protein expression in human primary tumor
colon cancer cell lines, such as DLD-1, HT-29 and one lymph node
metastatic cell line, SW620. Material and methods. CB1 gene
expression was determined using quantitative reverse
transcriptase-polymerase chain reaction (RT-PCR) in DLD-1, HT-29 and
SW620 cells treated at different times and doses of 17beta-estradiol
exposure. CB1 protein expression was detected by Western immunoblot.
Results. 17beta-estradiol induced CB1 gene expression in all the
human colon cancer cells studied. The early induction of CB1
receptor mRNA in DLD-1 and SW620 cells was mediated by the estrogen
receptor because the pure estrogen antagonist, ICI 182,780, was able
to counteract this effect. Estrogenic induction of the CB1 receptor
was also detectable at protein level in all cell types tested.
Conclusions. The CB1 receptor can be considered an
estrogen-responsive gene in DLD-1, HT-29 and SW620 cells.
Up-regulation of CB1 expression by 17beta-estradiol is a further
mechanism of estrogens to control colon cancer
proliferation. Delta(9)-Tetrahydrocannabinol (THC) and other cannabinoids inhibit tumour growth and angiogenesis in animal models, so their potential application as antitumoral drugs has been suggested. However, the antitumoral effect of cannabinoids has never been tested in humans. Here we report the first clinical study aimed at assessing cannabinoid antitumoral action, specifically a pilot phase I trial in which nine patients with recurrent glioblastoma multiforme were administered THC intratumoraly. The patients had previously failed standard therapy (surgery and radiotherapy) and had clear evidence of tumour progression. The primary end point of the study was to determine the safety of intracranial THC administration. We also evaluated THC action on the length of survival and various tumour-cell parameters. A dose escalation regimen for THC administration was assessed. Cannabinoid delivery was safe and could be achieved without overt psychoactive effects. Median survival of the cohort from the beginning of cannabinoid administration was 24 weeks (95% confidence interval: 15-33). Delta(9)-Tetrahydrocannabinol inhibited tumour-cell proliferation in vitro and decreased tumour-cell Ki67 immunostaining when administered to two patients. The fair safety profile of THC, together with its possible antiproliferative action on tumour cells reported here and in other studies, may set the basis for future trials aimed at evaluating the potential antitumoral activity of cannabinoids. --- Invasion and metastasis of aggressive
breast cancer cells is the final and fatal step during cancer
progression, and is the least understood genetically. Clinically,
there are still limited therapeutic interventions for aggressive and
metastatic breast cancers available. Clearly, effective and nontoxic
therapies are urgently required. Id-1, an inhibitor of basic
helix-loop-helix transcription factors, has recently been shown to
be a key regulator of the metastatic potential of breast and
additional cancers. Using a mouse model, we previously determined
that metastatic breast cancer cells became significantly less
invasive in vitro and less metastatic in vivo when Id-1 was
down-regulated by stable transduction with antisense Id-1. It is not
possible at this point, however, to use antisense technology to
reduce Id-1 expression in patients with metastatic breast cancer.
Here, we report that cannabidiol (CBD), a cannabinoid with a
low-toxicity profile, could down-regulate Id-1 expression in
aggressive human breast cancer cells. The CBD concentrations
effective at inhibiting Id-1 expression correlated with those used
to inhibit the proliferative and invasive phenotype of breast cancer
cells. CBD was able to inhibit Id-1 expression at the mRNA and
protein level in a concentration-dependent fashion. These effects
seemed to occur as the result of an inhibition of the Id-1 gene at
the promoter level. Importantly, CBD did not inhibit invasiveness in
cells that ectopically expressed Id-1. In conclusion, CBD represents
the first nontoxic exogenous agent that can significantly decrease
Id-1 expression in metastatic breast cancer cells leading to the
down-regulation of tumor aggressiveness. Delta9-Tetrahydrocannabinol, the main
active component of marijuana, induces apoptosis of transformed
neural cells in culture. Here, we show that intratumoral
administration of Delta9-tetrahydrocannabinol and the synthetic
cannabinoid agonist WIN-55,212-2 induced a considerable regression
of malignant gliomas in Wistar rats and in mice deficient in
recombination activating gene 2. Cannabinoid treatment did not
produce any substantial neurotoxic effect in the conditions used.
Experiments with two subclones of C6 glioma cells in culture showed
that cannabinoids signal apoptosis by a pathway involving
cannabinoid receptors, sustained ceramide accumulation and
Raf1/extracellular signal-regulated kinase activation. These results
may provide the basis for a new therapeutic approach for the
treatment of malignant gliomas. Pancreatic adenocarcinomas are among
the most malignant forms of cancer and, therefore, it is of especial
interest to set new strategies aimed at improving the prognostic of
this deadly disease. The present study was undertaken to investigate
the action of cannabinoids, a new family of potential antitumoral
agents, in pancreatic cancer. We show that cannabinoid receptors are
expressed in human pancreatic tumor cell lines and tumor biopsies at
much higher levels than in normal pancreatic tissue. Studies
conducted with MiaPaCa2 and Panc1 cell lines showed that cannabinoid
administration (a) induced apoptosis, (b) increased ceramide levels,
and (c) up-regulated mRNA levels of the stress protein p8. These
effects were prevented by blockade of the CB(2) cannabinoid receptor
or by pharmacologic inhibition of ceramide synthesis de novo.
Knockdown experiments using selective small interfering RNAs showed
the involvement of p8 via its downstream endoplasmic reticulum
stress-related targets activating transcription factor 4 (ATF-4) and
TRB3 in Delta(9)-tetrahydrocannabinol-induced apoptosis.
Cannabinoids also reduced the growth of tumor cells in two animal
models of pancreatic cancer. In addition, cannabinoid treatment
inhibited the spreading of pancreatic tumor cells. Moreover,
cannabinoid administration selectively increased apoptosis and TRB3
expression in pancreatic tumor cells but not in normal tissue. In
conclusion, results presented here show that cannabinoids lead to
apoptosis of pancreatic tumor cells via a CB(2) receptor and de novo
synthesized ceramide-dependent up-regulation of p8 and the
endoplasmic reticulum stress-related genes ATF-4 and TRB3. These
findings may contribute to set the basis for a new therapeutic
approach for the treatment of pancreatic
cancer. The development of new therapeutic
strategies is essential for the management of gliomas, one of the
most malignant forms of cancer. We have shown previously that the
growth of the rat glioma C6 cell line is inhibited by psychoactive
cannabinoids (I. Galve-Roperh et al., Nat. Med., 6: 313-319, 2000).
These compounds act on the brain and some other organs through the
widely expressed CB(1) receptor. By contrast, the other cannabinoid
receptor subtype, the CB(2) receptor, shows a much more restricted
distribution and is absent from normal brain. Here we show that
local administration of the selective CB(2) agonist JWH-133 at 50
microg/day to Rag-2(-/-) mice induced a considerable regression of
malignant tumors generated by inoculation of C6 glioma cells. The
selective involvement of the CB(2) receptor in this action was
evidenced by: (a) the prevention by the CB(2) antagonist SR144528
but not the CB(1) antagonist SR141716; (b) the down-regulation of
the CB(2) receptor but not the CB(1) receptor in the tumors; and (c)
the absence of typical CB(1)-mediated psychotropic side effects.
Cannabinoid receptor expression was subsequently examined in
biopsies from human astrocytomas. A full 70% (26 of 37) of the human
astrocytomas analyzed expressed significant levels of cannabinoid
receptors. Of interest, the extent of CB(2) receptor expression was
directly related with tumor malignancy. In addition, the growth of
grade IV human astrocytoma cells in Rag-2(-/-) mice was completely
blocked by JWH-133 administration at 50 microg/day. Experiments
carried out with C6 glioma cells in culture evidenced the
internalization of the CB(2) but not the CB(1) receptor upon JWH-133
challenge and showed that selective activation of the CB(2) receptor
signaled apoptosis via enhanced ceramide synthesis de novo. These
results support a therapeutic approach for the treatment of
malignant gliomas devoid of psychotropic side
effects. Special note: Most studies of cannabinoids in regard to diabetes are on the positive effects of CB1 antagonism and specifically on the positive effect of rimbonant, one particulare CB1 antagonist. Below ae the studies that show the positive efects of agonism instead. This is where interdisciplinary view is necessary to overcome the money-driven research impetus. Numerous studies show the tonic effect of cannabinoid agonism on the cells of the pancreas, the organ responsible for insulin production. Additionally, THC is fat soluable and is stored in fat. CB1 receptors are upregulated in the fat of obese subjects. Chronic administration of an agonist causes downregulation which acts as an analog of antagonism. http://www.ncbi.nlm.nih.gov/pubmed/16698671?ordinalpos=14&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum Cannabidiol lowers incidence of diabetes in non-obese diabetic mice.Weiss L, Zeira M, Reich S, Har-Noy M, Mechoulam R, Slavin S, Gallily R. Hadassah University Hospital, Department of Bone Marrow Transplantation & Cancer Immunotherapy, POB 12000, Jerusalem, 91120, Israel. Cannabidinoids are components of the Cannabis sativa
(marijuana) plant that have been shown capable of suppressing
inflammation and various aspects of cell-mediated immunity.
Cannabidiol (CBD), a non-psychoactive cannabidinoid has been
previously shown by us to suppress cell-mediated autoimmune joint
destruction in an animal model of rheumatoid arthritis. We now
report that CBD treatment significantly reduces the incidence of
diabetes in NOD mice from an incidence of 86% in non-treated control
mice to an incidence of 30% in CBD-treated mice. CBD treatment also
resulted in the significant reduction of plasma levels of the
pro-inflammatory cytokines, IFN-gamma and TNF-alpha. Th1-associated
cytokine production of in vitro activated T-cells and peritoneal
macrophages was also significantly reduced in CBD-treated mice,
whereas production of the Th2-associated cytokines, IL-4 and IL-10,
was increased when compared to untreated control mice. Histological
examination of the pancreatic islets of CBD-treated mice revealed
significantly reduced insulitis. Our results indicate that CBD can
inhibit and delay destructive insulitis and inflammatory
Th1-associated cytokine production in NOD mice resulting in a
decreased incidence of diabetes possibly through an immunomodulatory
mechanism shifting the immune response from Th1 to Th2
dominance. The endogenous cannabinoid system
(ECS) is a neuromodulatory system recently recognized to have a role
in the regulation of various aspects of eating behavior and energy
balance through central and peripheral mechanisms. In the central
nervous system, cannabinoid type 1 receptors and their endogenous
ligands, the endocannabinoids, are involved in modulating food
intake and motivation to consume palatable food. Moreover, the ECS
is present in peripheral organs, such as liver, white adipose
tissue, muscle, and pancreas, where it seems to be involved in the
regulation of lipid and glucose homeostasis. Dysregulation of the
ECS has been associated with the development of obesity and its
sequelae, such as dyslipidemia and diabetes. Conversely, recent
clinical trials have shown that cannabinoid type 1 receptor blockade
may ameliorate these metabolic abnormalities. Although further
investigation is needed to better define the actual mechanisms of
action, pharmacologic approaches targeting the ECS may provide a
novel, effective option for the management of obesity, type 2
diabetes and cardiovascular disease. OBJECTIVE: To review the role of the endogenous
cannabinoid system (ECS) in the peripheral and central regulation of
food intake, appetite, and energy storage and discuss the potential
for the ECS to be an important target for lowering cardiovascular
risk. METHODS: Materials used for this article were identified
through a MEDLINE search of the pertinent literature (1975 to
present), including English-language randomized controlled,
prospective, cohort, review, and observational studies. We summarize
the available experimental and clinical data. RESULTS: The ECS is
composed of two 7-transmembrane G protein-coupled cannabinoid
receptor subtypes, CB1 and CB2, endogenous cannabinoid ligands
(anandamide and 2-arachidonoylglycerol), and the enzymes that
synthesize and break down the ligands. Understanding the role of the
ECS in central and peripheral metabolic processes related to the
regulation of food intake and energy balance as well as the
endocrine role of excess adipose tissue, particularly visceral
adipose tissue, and its promotion of global cardiometabolic risk has
led to the development of pharmacologic agents with potential for
blockade of CB1 receptors. In several studies, rimonabant (20 mg
daily) demonstrated a favorable effect on various risk factors for
cardiovascular disease, including dyslipidemia, abdominal obesity,
insulin resistance, blood pressure, and measures of inflammation.
CONCLUSION: The ECS has been shown to have a key role in the
regulation of energy balance, and modulation of this system may
affect multiple cardiometabolic risk factors. Clinical studies
involving pharmacologic blockade of CB1 receptors in overweight
patients with and without type 2 diabetes have demonstrated
effective weight loss and improvements in several risk factors for
cardiovascular
disease. Human obesity has been associated
with a dysregulation of the peripheral and adipose tissue (AT)
endocannabinoid system (ES). The aim of this study was to elucidate
the acute in vivo effects of insulin on gene expression of the
cannabinoid type 1 (CB-1) and type 2 (CB-2) receptors, as well as of
the fatty acid amide hydrolase (FAAH) in the sc abdominal adipose
tissue (SCAAT). Nine lean (L) and 9 obese (OB), but otherwise
healthy males were studied in the fasting state and during a
euglycemic hyperinsulinemic clamp (40 mU/m2 * min(-1)). SCAAT
biopsies were obtained at baseline and after 270 min of i.v.
maintained hyperinsulinemia. The basal SCAAT gene expression pattern
revealed an upregulation of the FAAH in the OB (p=0.03 vs L),
whereas similar CB-1 and CB-2 mRNA levels were seen. Following
hyperinsulinemia, the FAAH mRNA levels significantly increased
approximately 2-fold in the L (p=0.01 vs baseline) but not in the
OB. In contrast, insulin failed to significantly change both the
adipose CB-1 and CB-2 gene expression. Finally, the FAAH gene
expression positively correlated with the fasting serum insulin
concentration (r 0.66; p=0.01), whereas an inverse association with
the whole-body glucose disposal (r -0.58; p<0.05) was seen. Taken
together, these first time observations demonstrate that the
ES-related genes in the SCAAT differentially respond to
hyperinsulinemia in lean/insulin-sensitive and in
obese/insulin-resistant individuals. We suggest that insulin may
play a key role in the obesity-linked dysregulation of the adipose
ES at the gene level. OBJECTIVE: To investigate the
ability of acute administration of the endogenous cannabinoid,
anandamide, in vitro to alter the nonadrenegic noncholinergic
(NANC)-mediated relaxation of corpus cavernosum (CC) in diabetic
rats and the possible role of nitric oxide (NO), as it is well known
that erectile dysfunction (ED) affects 35-75% of men with diabetes
mellitus and several studies have been conducted to find appropriate
strategies for treating diabetes-induced ED. MATERIALS AND METHODS:
Diabetes was induced in rats by streptozotocin administration and
was maintained for 8 weeks. The CC were removed and isolated in
organ baths for pharmacological studies. Agonist-evoked or
electrical-field stimulation (EFS)-evoked smooth muscle tensions in
CC strips from control and diabetic rats were measured. RESULTS: The
neurogenic relaxation of phenylephrine (7.5 microm)-precontracted
isolated CC strips was impaired in diabetic rats. Anandamide (0.3, 1
and 3 microm) enhanced the relaxant responses to EFS in diabetic CC
strips in a dose-dependent manner. This effect was antagonized by
the selective cannabinoid CB(1) receptor antagonist AM251 (1 microm)
and the selective vanilloid receptor antagonist capsazepine (3
microm). Concurrent administration of partially effective doses of
l-arginine (10 microm) and anandamide (0.3 microm) exerted a
synergistic improvement in EFS-induced relaxation of diabetic CC
strips (P < 0.001). The relaxant responses to the NO donor,
sodium nitroprusside, were similar between diabetic and control
groups. CONCLUSION; For the first time, we show that acute
administration of anandamide, an endogenous cannabinoid, alone or
combined with l-arginine can improve nitrergic nerve-mediated
relaxation of the CC in diabetic rats. This effect was mediated by
cannabinoid CB(1) and vanilloid VR(1) receptors within the
CC. AIMS/HYPOTHESIS: We examined the
presence of functional cannabinoid receptors 1 and 2 (CB1, CB2) in
isolated human islets, phenotyped the cells producing cannabinoid
receptors and analysed the actions of selective cannabinoid receptor
agonists on insulin, glucagon and somatostatin secretion in vitro.
We also described the localisation on islet cells of: (1) the
endocannabinoid-producing enzymes N-acyl-phosphatidyl
ethanolamine-hydrolysing phospholipase D and diacylglycerol lipase;
and (2) the endocannabinoid-degrading enzymes fatty acid
amidohydrolase and monoacyl glycerol lipase. METHODS: Real-time PCR,
western blotting and immunocytochemistry were used to analyse the
presence of endocannabinoid-related proteins and genes. Static
secretion experiments were used to examine the effects of activating
CB1 or CB2 on insulin, glucagon and somatostatin secretion and to
measure changes in 2-arachidonoylglycerol (2-AG) levels within
islets. Analyses were performed in isolated human islets and in
paraffin-embedded sections of human pancreas. RESULTS: Human islets
of Langerhans expressed CB1 and CB2 (also known as CNR1 and CNR2)
mRNA and CB1 and CB2 proteins, and also the machinery involved in
synthesis and degradation of 2-AG (the most abundant
endocannabinoid, levels of which were modulated by glucose).
Immunofluorescence revealed that CB1 was densely located in
glucagon-secreting alpha cells and less so in insulin-secreting beta
cells. CB2 was densely present in somatostatin-secreting delta
cells, but absent in alpha and beta cells. In vitro experiments
revealed that CB1 stimulation enhanced insulin and glucagon
secretion, while CB2 agonism lowered glucose-dependent insulin
secretion, showing these cannabinoid receptors to be functional.
CONCLUSIONS/INTERPRETATION: Together, these results suggest a role
for endogenous endocannabinoid signalling in regulation of endocrine
secretion in the human pancreas. delta9-Tetrahydrocannabinol (delta9-THC) is capable of modulating a variety of immune responses, but has not been evaluated in models of immune-based diabetes. The objectives of the present study were: (a) to investigate the effect of delta9-THC in an established model of multiple low dose streptozotocin (MLDSTZ)-induced autoimmune diabetes; and (b) to determine the contribution of the immune response in the MLDSTZ model. CD-1 mice were treated with 40 mg/kg STZ for 5 days in the presence or absence of delta9-THC treatment. delta9-THC administered orally in corn oil at 150 mg/kg for 11 days attenuated, in a transient manner, the MLDSTZ-induced elevation in serum glucose and loss of pancreatic insulin. MLDSTZ-induced insulitis and increases in IFN-gamma, TNFalpha and IL-12 mRNA expression were all reduced on Day 11 by co-administration of delta9-THC. In separate studies, six doses of delta9-THC, given after completion of STZ treatment, was found equally effective in attenuating mice from MLDSTZ-induced diabetes. Studies performed using B6C3F1 mice showed moderate hyperglycemia and a significant reduction in pancreatic insulin by MLDSTZ in the absence of insulitis. In addition, MLDSTZ produced a less pronounced hyperglycemia compared to CD-1 mice that was not attenuated by delta9-THC. These results suggest that MLDSTZ can initiate direct beta-cell damage, thereby augmenting the destruction of beta-cells by the immune system. Moreover, these results indicate that delta9-THC is capable of attenuating the severity of the autoimmune response in this experimental model of autoimmune diabetes. --- http://www.ncbi.nlm.nih.gov/pubmed/17499236?ordinalpos=9&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum Here we show that the activation of cannabinoid CB2
receptors improved glucose tolerance after a glucose load. Blockade
of cannabinoid CB2 receptors counteracted this effect, leading to
glucose intolerance. Since blockade of cannabinoid CB1 receptors
mimics the actions of cannabinoid CB2 receptor agonists, we propose
that the endocannabinoid system modulates glucose homeostasis
through the coordinated actions of cannabinoid CB1 and CB2
receptors. We also describe the presence of both cannabinoid CB1 and
CB2 receptor immunoreactivity in rat pancreatic beta- and
non-beta-cells, adding the endocrine pancreas to adipose tissue and
the liver as potential sites for endocannabinoid regulation of
glucose homeostasis. CONTEXT: Cannabinoid CB(1) receptor blockade decreases weight and hyperinsulinemia in obese animals and humans in a way greatly independent from food intake. OBJECTIVE: The objective of this study was to investigate the regulation and function of the endocannabinoid system in adipocytes and pancreatic beta-cells. DESIGN, SETTING, AND PATIENTS: Mouse 3T3-F442A adipocytes and rat insulinoma RIN-m5F beta-cells, pancreas and fat from mice with diet-induced obesity, visceral and sc fat from patients with body mass index equal to or greater than 30 kg/m(2), and serum from normoglycemic and type 2 diabetes patients were studied. MAIN OUTCOME MEASURE: Endocannabinoid enzyme and adipocyte protein expression, and endocannabinoid and insulin levels were measured. RESULTS: Endocannabinoids are present in adipocytes with levels peaking before differentiation, and in RIN-m5F beta-cells, where they are under the negative control of insulin. Chronic treatment of adipocytes with insulin is accompanied by permanently elevated endocannabinoid signaling, whereas culturing of RIN-m5F beta-cells in high glucose transforms insulin down-regulation of endocannabinoid levels into up-regulation. Epididymal fat and pancreas from mice with diet-induced obesity contain higher endocannabinoid levels than lean mice. Patients with obesity or hyperglycemia caused by type 2 diabetes exhibit higher concentrations of endocannabinoids in visceral fat or serum, respectively, than the corresponding controls. CB(1) receptor stimulation increases lipid droplets and decreases adiponectin expression in adipocytes, and it increases intracellular calcium and insulin release in RIN-m5F beta-cells kept in high glucose. CONCLUSIONS: Peripheral endocannabinoid overactivity might explain why CB(1) blockers cause weight-loss independent reduction of lipogenesis, of hypoadiponectinemia, and of hyperinsulinemia in obese animals and humans. --- BACKGROUND: While cannabinoids have been shown to ameliorate liver fibrosis, their effects in chronic pancreatitis and on pancreatic stellate cells (PSC) are unknown. METHODOLOGY/PRINCIPAL FINDINGS: The activity of the endocannabinoid system was evaluated in human chronic pancreatitis (CP) tissues. In vitro, effects of blockade and activation of cannabinoid receptors on pancreatic stellate cells were characterized. In CP, cannabinoid receptors were detected predominantly in areas with inflammatory changes, stellate cells and nerves. Levels of endocannabinoids were decreased compared with normal pancreas. Cannabinoid-receptor-1 antagonism effectuated a small PSC phenotype and a trend toward increased invasiveness. Activation of cannabinoid receptors, however, induced de-activation of PSC and dose-dependently inhibited growth and decreased IL-6 and MCP-1 secretion as well as fibronectin, collagen1 and alphaSMA levels. De-activation of PSC was partially reversible using a combination of cannabinoid-receptor-1 and -2 antagonists. Concomitantly, cannabinoid receptor activation specifically decreased invasiveness of PSC, MMP-2 secretion and led to changes in PSC phenotype accompanied by a reduction of intracellular stress fibres. CONCLUSIONS/SIGNIFICANCE: Augmentation of the endocannabinoid system via exogenously administered cannabinoid receptor agonists specifically induces a functionally and metabolically quiescent pancreatic stellate cell phenotype and may thus constitute an option to treat inflammation and fibrosis in chronic pancreatitis. --- Cannabinoids kill pancreeatic tumors Pancreatic adenocarcinomas are among the most malignant forms of cancer and, therefore, it is of especial interest to set new strategies aimed at improving the prognostic of this deadly disease. The present study was undertaken to investigate the action of cannabinoids, a new family of potential antitumoral agents, in pancreatic cancer. We show that cannabinoid receptors are expressed in human pancreatic tumor cell lines and tumor biopsies at much higher levels than in normal pancreatic tissue. Studies conducted with MiaPaCa2 and Panc1 cell lines showed that cannabinoid administration (a) induced apoptosis, (b) increased ceramide levels, and (c) up-regulated mRNA levels of the stress protein p8. These effects were prevented by blockade of the CB(2) cannabinoid receptor or by pharmacologic inhibition of ceramide synthesis de novo. Knockdown experiments using selective small interfering RNAs showed the involvement of p8 via its downstream endoplasmic reticulum stress-related targets activating transcription factor 4 (ATF-4) and TRB3 in Delta(9)-tetrahydrocannabinol-induced apoptosis. Cannabinoids also reduced the growth of tumor cells in two animal models of pancreatic cancer. In addition, cannabinoid treatment inhibited the spreading of pancreatic tumor cells. Moreover, cannabinoid administration selectively increased apoptosis and TRB3 expression in pancreatic tumor cells but not in normal tissue. In conclusion, results presented here show that cannabinoids lead to apoptosis of pancreatic tumor cells via a CB(2) receptor and de novo synthesized ceramide-dependent up-regulation of p8 and the endoplasmic reticulum stress-related genes ATF-4 and TRB3. These findings may contribute to set the basis for a new therapeutic approach for the treatment of pancreatic cancer. --- Cannabinoids treat pancreatitis BACKGROUND & AIMS: The functional involvement of
the endocannabinoid system in modulation of pancreatic inflammation,
such as acute pancreatitis, has not been studied to date. Moreover,
the therapeutic potential of cannabinoids in pancreatitis has not
been addressed. METHODS: We quantified endocannabinoid levels and
expression of cannabinoid receptors 1 and 2 (CB1 and CB2) in
pancreas biopsies from patients and mice with acute pancreatitis.
Functional studies were performed in mice using pharmacological
interventions. Histological examination, serological, and molecular
analyses (lipase, myeloperoxidase, cytokines, and chemokines) were
performed to assess disease pathology and inflammation. Pain
resulting from pancreatitis was studied as abdominal
hypersensitivity to punctate von Frey stimuli. Behavioral analyses
in the open-field, light-dark, and catalepsy tests were performed to
judge cannabinoid-induced central side effects. RESULTS: Patients
with acute pancreatitis showed an up-regulation of cannabinoid
receptors and elevated levels of endocannabinoids in the pancreas.
HU210, a synthetic agonist at CB1 and CB2, abolished abdominal pain
associated with pancreatitis and also reduced inflammation and
decreased tissue pathology in mice without producing central,
adverse effects. Antagonists at CB1- and CB2-receptors were
effective in reversing HU210-induced antinociception, whereas a
combination of CB1- and CB2-antagonists was required to block the
anti-inflammatory effects of HU210 in pancreatitis. CONCLUSIONS: In
humans, acute pancreatitis is associated with up-regulation of
ligands as well as receptors of the endocannabinoid system in the
pancreas. Furthermore, our results suggest a therapeutic potential
for cannabinoids in abolishing pain associated with acute
pancreatitis and in partially reducing inflammation and disease
pathology in the absence of adverse side effects. Osteoporosis http://www.ncbi.nlm.nih.gov/pubmed/16407142?ordinalpos=9&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum Peripheral cannabinoid receptor, CB2, regulates bone mass.Ofek O, Karsak M, Leclerc N, Fogel M, Frenkel B, Wright K, Tam J, Attar-Namdar M, Kram V, Shohami E, Mechoulam R, Zimmer A, Bab I. Bone Laboratory, Hebrew University of Jerusalem, Jerusalem 91120, Israel. The endogenous cannabinoids bind to and activate two G
protein-coupled receptors, the predominantly central cannabinoid
receptor type 1 (CB1) and peripheral cannabinoid receptor type 2
(CB2). Whereas CB1 mediates the cannabinoid psychotropic, analgesic,
and orectic effects, CB2 has been implicated recently in the
regulation of liver fibrosis and atherosclerosis. Here we show that
CB2-deficient mice have a markedly accelerated age-related
trabecular bone loss and cortical expansion, although cortical
thickness remains unaltered. These changes are reminiscent of human
osteoporosis and may result from differential regulation of
trabecular and cortical bone remodeling. The CB2(-/-) phenotype is
also characterized by increased activity of trabecular osteoblasts
(bone-forming cells), increased osteoclast (the bone-resorbing cell)
number, and a markedly decreased number of diaphyseal osteoblast
precursors. CB2 is expressed in osteoblasts, osteocytes, and
osteoclasts. A CB2-specific agonist that does not have any
psychotropic effects enhances endocortical osteoblast number and
activity and restrains trabecular osteoclastogenesis, apparently by
inhibiting proliferation of osteoclast precursors and receptor
activator of NF-kappaB ligand expression in bone marrow-derived
osteoblasts/stromal cells. The same agonist attenuates
ovariectomy-induced bone loss and markedly stimulates cortical
thickness through the respective suppression of osteoclast number
and stimulation of endocortical bone formation. These results
demonstrate that the endocannabinoid system is essential for the
maintenance of normal bone mass by osteoblastic and osteoclastic CB2
signaling. Hence, CB2 offers a molecular target for the diagnosis
and treatment of osteoporosis, the most prevalent degenerative
disease in developed countries. Oral administration of ajulemic acid (AjA), a cannabinoid acid devoid of psychoactivity, prevents joint tissue injury in rats with adjuvant induced arthritis. Because activation of osteoclasts is central to the pathogenesis of bone erosion in patients with rheumatoid arthritis (RA), we investigated the influence of AjA on osteoclast differentiation and survival. Osteoclast cultures were established by stimulation of RAW264.7 cells and primary mouse bone marrow cultures with receptor activator of NF-kappaB ligand (RANKL). Simultaneous addition of AjA (15 and 30 microM) and RANKL to both culture systems significantly suppressed development of multinucleated osteoclasts (osteoclastogenesis) in a dose dependent manner, as determined by quantification of multinuclear, tartrate-resistant acid phosphatase (TRAP)-positive cells. AjA impaired growth of RAW264.7 monocytes and prevented further osteoclast formation in cultures in which osteoclastogenesis had already begun. Reduction by AjA of both monocyte growth and osteoclast formation was associated with apoptosis, assayed by annexin V and propidium iodide staining, and caspase activity. The anti-osteoclastogenic effects of AjA did not require the continuous presence of AjA in the cell cultures. Based on these findings, we propose that AjA or other nonpsychoactive synthetic analogs of Cannabis constituents may be useful therapy for diseases such as RA and osteoporosis in which bone resorption is a central feature. (c) 2007 Wiley-Liss, Inc. --- Osteoporosis is one of the most common degenerative diseases.
It is characterized by reduced bone mineral density (BMD) with an
increased risk for bone fractures. There is a substantial genetic
contribution to BMD, although the genetic factors involved in the
pathogenesis of human osteoporosis are largely unknown. Mice with a
targeted deletion of either the cannabinoid receptor type 1 (Cnr1)
or type 2 (Cnr2) gene show an alteration of bone mass, and
pharmacological modification of both receptors can regulate
osteoclast activity and BMD. We therefore analyzed both genes in a
systematic genetic association study in a human sample of
postmenopausal osteoporosis patients and matched female controls. We
found a significant association of single polymorphisms (P = 0.0014)
and haplotypes (P = 0.0001) encompassing the CNR2 gene on human
chromosome 1p36, whereas we found no convincing association for
CNR1. These results demonstrate a role for the peripherally
expressed CB2 receptor in the etiology of osteoporosis and provide
an interesting novel therapeutical target for this severe and common
disease. http://www.ncbi.nlm.nih.gov/pubmed/17140265?ordinalpos=5&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum Alzheimer's disease is the leading
cause of dementia among the elderly, and with the ever-increasing
size of this population, cases of Alzheimer's disease are expected
to triple over the next 50 years. Consequently, the development of
treatments that slow or halt the disease progression have become
imperative to both improve the quality of life for patients and
reduce the health care costs attributable to Alzheimer's disease.
Here, we demonstrate that the active component of marijuana,
Delta9-tetrahydrocannabinol (THC), competitively inhibits the enzyme
acetylcholinesterase (AChE) as well as prevents AChE-induced amyloid
beta-peptide (Abeta) aggregation, the key pathological marker of
Alzheimer's disease. Computational modeling of the THC-AChE
interaction revealed that THC binds in the peripheral anionic site
of AChE, the critical region involved in amyloidgenesis.
Compared to currently approved drugs prescribed for the
treatment of Alzheimer's disease, THC is a considerably superior
inhibitor of Abeta aggregation, and this study provides a
previously unrecognized molecular mechanism through which
cannabinoid molecules may directly impact the progression of this
debilitating disease. The endocannabinoid system is still
poorly understood. Recently, the basic elements that constitute it,
i.e., membrane receptors, endogenous ligands, and mechanisms for
termination of the signaling process, have been partially
characterized. There is a considerable lack of information, however,
concerning the distribution, concentration, and function of those
components in the human body, particularly during pathological
events. We have studied the status of some of the components of the
endocannabinoid system, fatty acid amide hydrolase and cannabinoid
CB1 and CB2 receptors, in postmortem brains from patients with
Alzheimer's disease. Using specific polyclonal antibodies, we have
performed immunohistochemical analysis in hippocampus and entorhinal
cortex sections from brains of Alzheimer's disease patients. Our
results show that both fatty acid amide hydrolase and cannabinoid
CB2 receptors are abundantly and selectively expressed in neuritic
plaque-associated astrocytes and microglia, respectively, whereas
the expression of CB1 receptors remains unchanged. In addition, the
hydrolase activity seems to be elevated in the plaques and
surrounding areas. Thus, some elements of the endocannabinoid system
may be postulated as possible modulators of the inflammatory
response associated with this neurodegenerative process and as
possible targets for new therapeutic
approaches. Alzheimer's disease (AD) is
characterized by enhanced beta-amyloid peptide (betaA) deposition
along with glial activation in senile plaques, selective neuronal
loss, and cognitive deficits. Cannabinoids are neuroprotective
agents against excitotoxicity in vitro and acute brain damage in
vivo. This background prompted us to study the localization,
expression, and function of cannabinoid receptors in AD and the
possible protective role of cannabinoids after betaA treatment, both
in vivo and in vitro. Here, we show that senile plaques in AD
patients express cannabinoid receptors CB1 and CB2, together with
markers of microglial activation, and that CB1-positive neurons,
present in high numbers in control cases, are greatly reduced in
areas of microglial activation. In pharmacological experiments, we
found that G-protein coupling and CB1 receptor protein expression
are markedly decreased in AD brains. Additionally, in AD brains,
protein nitration is increased, and, more specifically, CB1 and CB2
proteins show enhanced nitration. Intracerebroventricular
administration of the synthetic cannabinoid WIN55,212-2 to rats
prevent betaA-induced microglial activation, cognitive impairment,
and loss of neuronal markers. Cannabinoids (HU-210, WIN55,212-2, and
JWH-133) block betaA-induced activation of cultured microglial
cells, as judged by mitochondrial activity, cell morphology, and
tumor necrosis factor-alpha release; these effects are independent
of the antioxidant action of cannabinoid compounds and are also
exerted by a CB2-selective agonist. Moreover, cannabinoids abrogate
microglia-mediated neurotoxicity after betaA addition to rat
cortical cocultures. Our results indicate that cannabinoid receptors
are important in the pathology of AD and that cannabinoids succeed
in preventing the neurodegenerative process occurring in the
disease. --- http://www.ncbi.nlm.nih.gov/pubmed/17828287?ordinalpos=6&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum Alzheimer's disease; taking the edge off with cannabinoids?Campbell VA, Gowran A. Department of Physiology and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland. vacmpbll@tcd.ie Alzheimer's disease is an age-related neurodegenerative condition associated with cognitive decline. The pathological hallmarks of the disease are the deposition of beta-amyloid protein and hyperphosphorylation of tau, which evoke neuronal cell death and impair inter-neuronal communication. The disease is also associated with neuroinflammation, excitotoxicity and oxidative stress. In recent years the proclivity of cannabinoids to exert a neuroprotective influence has received substantial interest as a means to mitigate the symptoms of neurodegenerative conditions. In brains obtained from Alzheimer's patients alterations in components of the cannabinoid system have been reported, suggesting that the cannabinoid system either contributes to, or is altered by, the pathophysiology of the disease. Certain cannabinoids can protect neurons from the deleterious effects of beta-amyloid and are capable of reducing tau phosphorylation. The propensity of cannabinoids to reduce beta-amyloid-evoked oxidative stress and neurodegeneration, whilst stimulating neurotrophin expression neurogenesis, are interesting properties that may be beneficial in the treatment of Alzheimer's disease. Delta 9-tetrahydrocannabinol can also inhibit acetylcholinesterase activity and limit amyloidogenesis which may improve cholinergic transmission and delay disease progression. Targeting cannabinoid receptors on microglia may reduce the neuroinflammation that is a feature of Alzheimer's disease, without causing psychoactive effects. Thus, cannabinoids offer a multi-faceted approach for the treatment of Alzheimer's disease by providing neuroprotection and reducing neuroinflammation, whilst simultaneously supporting the brain's intrinsic repair mechanisms by augmenting neurotrophin expression and enhancing neurogenesis. The evidence supporting a potential role for the cannabinoid system as a therapeutic target for the treatment of Alzheimer's disease will be reviewed herewith. ---
Cures cirrhosis by combatting fibrosis,
the cause of cirrhosis
http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=
Allergic contact dermatitis affects about 5% of men and 11%
of women in industrialized countries and is one of the leading
causes for occupational diseases. In an animal model for cutaneous
contact hypersensitivity, we show that mice lacking both known
cannabinoid receptors display exacerbated allergic inflammation. In
contrast, fatty acid amide hydrolase-deficient mice, which have
increased levels of the endocannabinoid anandamide, displayed
reduced allergic responses in the skin. Cannabinoid receptor
antagonists exacerbated allergic inflammation, whereas receptor
agonists attenuated inflammation. These results demonstrate a
protective role of the endocannabinoid system in contact allergy in
the skin and suggest a target for therapeutic
intervention.
Acquisition and storage of aversive memories is
one of the basic principles of central nervous systems throughout
the animal kingdom. In the absence of reinforcement, the resulting
behavioural response will gradually diminish to be finally extinct.
Despite the importance of extinction, its cellular mechanisms are
largely unknown. The cannabinoid receptor 1 (CB1) and
endocannabinoids are present in memory-related brain areas and
modulate memory. Here we show that the endogenous cannabinoid system
has a central function in extinction of aversive memories.
CB1-deficient mice showed strongly impaired short-term and long-term
extinction in auditory fear-conditioning tests, with unaffected
memory acquisition and consolidation. Treatment of wild-type mice
with the CB1 antagonist SR141716A mimicked the phenotype of
CB1-deficient mice, revealing that CB1 is required at the moment of
memory extinction. Consistently, tone presentation during extinction
trials resulted in elevated levels of endocannabinoids in the
basolateral amygdala complex, a region known to control extinction
of aversive memories. In the basolateral amygdala, endocannabinoids
and CB1 were crucially involved in long-term depression of GABA
(gamma-aminobutyric acid)-mediated inhibitory currents. We propose
that endocannabinoids facilitate extinction of aversive memories
through their selective inhibitory effects on local inhibitory
networks in the amygdala. The interaction of the cannabinoid CB1 receptor
with its endogenous ligands plays an essential role in extinction of
aversive memories (Marsicano, G., Wotjak, C.T., Azad, S.C., Bisogno,
T., Rammes, G., Cascio, M.G., Hermann, H., Tang, J., Hofmann, C.,
Zieglgansberger, W., Di, M., V, Lutz, B., 2002. The endogenous
cannabinoid system controls extinction of aversive memories. Nature
418, 530-534). The present study tested the generality of this
observation in respect to positively-reinforced memories. To this
end, male cannabinoid CB1 receptor deficient mice (CB1R-/-) and
their wild-type littermate controls (CB1R+/+) were trained in an
appetitively-motivated operant conditioning task, in which
food-deprived animals received a food reward on nose-poking into an
illuminated hole. During training, CB1R-/- turned out to be less
motivated to participate in the task. After further restriction of
daily food consumption, however, CB1R-/- reached the same level of
performance as CB1R+/+ as far as number of correct responses and
errors of omission are concerned. The accuracy of performance served
as a measure for the memory of the light-reward association and was
stable at similarly high levels over a retention period of 9 days
without additional training (97.6+/-0.5% vs. 97.0+/-0.9% correct
responses). During subsequent extinction training, the positive
reinforcement was omitted. As a consequence, both CB1R-/- and
CB1R+/+ showed a similar decline in accuracy of performance and
total number of correct responses, accompanied by an increase in
errors of omission. These data demonstrate that the cannabinoid CB1
receptor is not essential for extinction of the stimulus-response
association in an appetitively-motivated learning
task. Attention deficit hyperactivity disorder (ADHD) is a highly heritable disorder affecting some 5-10% of children and 4-5% of adults. The cannabinoid receptor gene (CNR1) is a positional candidate gene due to its location near an identified ADHD linkage peak on chromosome 6, its role in stress and dopamine regulation, its association with other psychiatric disorders that co-occur with ADHD, and its function in learning and memory. We tested SNP variants at the CNR1 gene in two independent samples-an unselected adolescent sample from Northern Finland, and a family-based sample of trios (an ADHD child and their parents). In addition to using the trios for association study, the parents (with and without ADHD) were used as an additional case/control sample of adults for association tests. ADHD and its co-morbid psychiatric disorders were examined. A significant association was detected for a SNP haplotype (C-G) with ADHD (P = 0.008). A sex by genotype interaction was observed as well with this haplotype posing a greater risk in males than females. An association of an alternative SNP haplotype in this gene was found for post-traumatic stress disorder (PTSD) (P = 0.04 for C-A, and P = 0.01 for C-G). These observations require replication, however, they suggest that the CNR1 gene may be a risk factor for ADHD and possibly PTSD, and that this gene warrants further investigation for a role in neuropsychiatric disorders. (c) 2008 Wiley-Liss, Inc.
Two topics are presented in this review. In the first section, we review data regarding the effects of the endocannabinoids (eCBs) and cannabinoid receptors on neuroimmune function. The function of eCBs in the interaction between the immune system and the central nervous system (CNS) is of particular interest, since the CNS itself is a rich source of eCBs while being exquisitely sensitive to inflammation. There are several sites at which cannabinoids can influence neuroinflammation. Microglial cells express both CB receptors and make eCBs. Activation of CB receptors on these cells seems to promote migration and proliferation but to reduce activation to macrophages. In several neurodegenerative diseases, up-regulation of microglial CB2 receptors have been observed. It is our hypothesis that microglial CB receptor activity is anti-inflammatory and could be exploited to manipulate neuroinflammatory processes with a minimum of unwanted effects. The second topic discussed suggests that the eCB/CB1 receptor pair is involved in the responses of animals to acute, repeated and variable stress. The roles of this pair are complex and dependent upon previous stress, among other things. Dysfunctional responding to stress is a component of several human neuropsychiatric disorders, including anxiety and panic disorders, post-traumatic stress disorders, premenstrual dysphoria and quite possibly, drug abuse. While it is too early to say with certainty, it is very possible that either inhibition or potentiation of endocannabinoid signaling will be an efficacious novel therapeutic approach to more than one human psychiatric disease.
Fear builds up without CB1 Previous studies have suggested that the endocannabinoid CB1
receptor (ECBR) system is involved in stress. However, the nature of
this association is complex. Here, we investigated the role of CB1
receptors in the response to stress by comparing the effects of
various stress modalities in CB1-/- receptor deficient and wild-type
mice, at adulthood and during early development. Response to acute
stress was assayed by plasma corticosterone (CS) and
adrenocorticotrophic hormone (ACTH), USVs and motor inhibition. The
response to repeated stress was assessed by USVs and motor
inhibition. Since repeated bell stress seemed to cause a cumulative
fear in CB1 receptor knockout mice, these behavioral responses were
also compared to those observed after a single severe stress (forced
swimming). In wild-type, but not in CB1 receptor knockout mice, bell
stress-induced elevations of ACTH and CS were significant. The first
exposure to bell stress had no significant effect on USVs or
mobility. Upon repeated exposures, significant suppression of USVs,
together with behavioral inhibition, were observed in CB1 knockout
but not in wild-type mice. Swim stress inhibited USVs in the
knockout animals, and the profound motor inhibition displayed by all
animals was greater and more prolonged in the CB1-/- mice. Since the
knockout mice lack the CB1 receptor throughout pre- and postnatal
life, the stress response in pups was also assayed (by
separation-induced USVs). Wild-type pups displayed the
characteristic developmental peak in USV emissions; it was
completely lacking in knockout pups. We conclude that acutely, the
absence of CB1 receptors reduces the neuroendocrine response and
does not affect the behavioral response to moderate stress. However,
upon repeated stress or acute severe stress, CB1 receptor deficiency
causes persistent behavioral inhibition. Finally, the CB1 receptor
plays a role in modulating the stress response from an early age.
These observations suggest that CB1 receptors participate in the
mediation of the stress response and that the absence of these
receptors results in a greater vulnerability to stress. We suggest
that the stress-induced endocrine and behavioral suppression in CB1
receptor deficient mice may serve as a model for some forms of
post-traumatic stress disorder (PTSD). Further, the role of CB1
receptors in coping with stress is a lifelong function. Finally,
although equivalent research has not been performed in human
infants, the postnatal suppression of the stress response in CB1
receptor knockout pups may have implications when cannabinoid-based
therapy is considered for children. Preventing breakdown of endocannabinoid caused faster
learning and faster purposeful unlearning of tasks. Poor controls on
secondary tests of THC conflict with other studies.. Recent reports have demonstrated that disruption of CB(1)
receptor signaling impairs extinction of learned responses in
conditioned fear and Morris water maze paradigms. Here, we test the
hypothesis that elevating brain levels of the endogenous cannabinoid
anandamide through either genetic deletion or pharmacological
inhibition of its primary catabolic enzyme fatty-acid amide
hydrolase (FAAH) will potentiate extinction in a fixed platform
water maze task. FAAH (-/-) mice and mice treated with the FAAH
inhibitor OL-135, did not display any memory impairment or motor
disruption, but did exhibit a significant increase in the rate of
extinction. Unexpectedly, FAAH-compromised mice also exhibited a
significant increase in acquisition rate. The CB(1) receptor
antagonist SR141716 (rimonabant) when given alone had no effects on
acquisition, but disrupted extinction. Additionally, SR141716
blocked the effects of OL-135 on both acquisition and extinction.
Collectively, these results indicate that endogenous anandamide
plays a facilitatory role in extinction through a CB(1) receptor
mechanism of action. In contrast, the primary psychoactive
constituent of marijuana, Delta(9)-tetrahydrocannabinol, failed to
affect extinction rates, suggesting that FAAH is a more effective
target than a direct acting CB(1) receptor agonist in facilitating
extinction. More generally, these findings suggest that FAAH
inhibition represents a promising pharmacological approach to treat
psychopathologies hallmarked by an inability to extinguish
maladaptive behaviors, such as post-traumatic stress syndrome and
obsessive-compulsive disorder. The endocannabinoid system has emerged as a versatile
neuromodulatory system, implicated in a plethora of physiological
and pathophysiological processes. Cannabinoid receptor type 1 (CB1
receptor) and endocannabinoids are widely distributed in the brain.
Their roles in learning and memory have been well documented, using
rodents in various memory tests. Depending on the test, the
endocannabinoid system is required in the acquisition and/or
extinction of memory. In particular, the activation of CB1
receptor-mediated signaling is centrally involved in the
facilitation of behavioral adaptation after the acquisition of
aversive memories. As several human psychiatric disorders, such as
phobia, generalized anxiety disorders, and posttraumatic stress
disorder (PTSD) appear to involve aberrant memory processing and
impaired adaptation to changed environmental conditions, the hope
has been fuelled that the endocannabinoid system might be a valuable
therapeutic target for the treatment of these disorders. This review
summarizes the current data on the role of the endocannabinoid
system in the modulation of extinction
learning.
Preclinical and clinical studies show
that cannabis modulates mood and possesses antidepressant-like
properties, mediated by the agonistic activity of cannabinoids on
central CB1 receptors (CB1Rs). The action of CB1R agonists on the
serotonin (5-HT) system, the major transmitter system involved in
mood control and implicated in the mechanism of action of
antidepressants, remains however poorly understood. In this study,
we demonstrated that, at low doses, the CB1R agonist WIN55,212-2
[R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthalenyl)
methanone mesylate] exerts potent antidepressant-like properties in
the rat forced-swim test (FST). This effect is CB1R dependent
because it was blocked by the CB1R antagonist rimonabant and is 5-HT
mediated because it was abolished by pretreatment with the
5-HT-depleting agent parachlorophenylalanine. Then, using in vivo
electrophysiology, we showed that low doses of WIN55,212-2 dose
dependently enhanced dorsal raphe nucleus 5-HT neuronal activity
through a CB1R-dependent mechanism. Conversely, high doses of
WIN55,212-2 were ineffective in the FST and decreased 5-HT neuronal
activity through a CB1R-independent mechanism. The CB1R
agonist-induced enhancement of 5-HT neuronal activity was abolished
by total or medial prefrontocortical, but not by lateral
prefrontocortical, transection. Furthermore, 5-HT neuronal activity
was enhanced by the local microinjection of WIN55,212-2 into the
ventromedial prefrontal cortex (mPFCv) but not by the local
microinjection of WIN55,212-2 into the lateral prefrontal cortex.
Similarly, the microinjection of WIN55,212-2 into the mPFCv produced
a CB1R-dependent antidepressant-like effect in the FST. These
results demonstrate that CB1R agonists possess antidepressant-like
properties and modulate 5-HT neuronal activity via the
mPFCv. Cannabinoids are well known modulators of
mood and emotional behavior. Current research supports a role for
endocannabinoid signaling in the treatment of depression. Changes in
levels of the cannabinoid CB(1) receptor or the endogenous CB(1)
receptor ligands, anandamide and 2-AG, are observed both in humans
suffering from depression and in animal models of depression, and
experimental manipulation of CB(1) receptor signaling has also been
shown to affect emotional reactivity in rodents. Importantly,
inhibitors of anandamide inactivation have demonstrated efficacy in
enhancing stress-coping and mood-related behavior. This article will
review these areas of research, highlighting the potential of
endocannabinoid metabolism modulators as therapeutics for the
treatment of
depression. http://www.ncbi.nlm.nih.gov/pubmed/18021439?ordinalpos=5&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum ABSTRACT: The present review synthetically describes the currently advanced hypotheses for a neurobiological basis of depression, ranging from the classical monoaminergic to the more recent neurotrophic hypothesis. Moreover, the Authors review the available preclinical and clinical evidence suggesting a possible role for the endocannabinoid system in the physiopathology of depression. Indeed, in spite of the reporting of conflicting results, the pharmacological enhancement of endocannabinoid activity at the CB1 cannabinoid receptor level appears to exert an antidepressant-like effect in some animal models of depression. On the contrary, a reduced activity of the endogenous cannabinoid system seems to be associated with the animal model of depression, namely the chronic mild stress model. Moreover, a few studies have reported an interaction of antidepressants with the endocannabinoid system. With regard to clinical studies, several authors have reported an alteration of endocannabinoid serum levels in depression, while post mortem studies have demonstrated increased levels of endocannabinoids associated to a concomitant hyperactivity of CB1 receptor in the prefrontal cortex of suicide victims. No clinical trials carried out using cannabinoids in the treatment of affective disorders have been published to date, although anecdotal reports have described both antidepressant and antimanic properties of cannabis as well as the ability of cannabis to induce mania that has also been documented. These findings are discussed, leading us to conclude that, although data available are sufficient to suggest a possible involvement of the endogenous cannabinoid system in the neurobiology of depression, additional studies should be performed in order to better elucidate the role of this system in the physiopathology of depression --- http://www.ncbi.nlm.nih.gov/pubmed/17762511?ordinalpos=10&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum Systemic administration of direct
cannabinoid CB1 receptor agonists and inhibitors of the hydrolytic
enzyme fatty acid amide hydrolase have been shown to elicit
antidepressant effects. Moreover, the endocannabinoid system in the
hippocampus is sensitive to both chronic stress and antidepressant
administration, suggesting a potential role of this system in
emotional changes associated with these regimens. The aim of this
study was to determine if cannabinoid CB1 receptors in the
hippocampus modulate emotionality in rats as assessed via the forced
swim test. Male Sprague-Dawley rats were bilaterally implanted with
cannulae directed at the dentate gyrus of the dorsal hippocampus and
subsequently received three infusions of either the cannabinoid CB1
receptor agonist HU-210 (1 and 2.5 microg), the fatty acid amide
hydrolase inhibitor URB597 (0.5 and 1 microg), the cannabinoid CB1
receptor antagonist AM251 (1 and 2.5 microg), or vehicle (dimethyl
sulfoxide) and were assessed in the forced swim test. Infusion of
both doses of HU-210 resulted in a dramatic reduction in immobility
and increase in swimming behaviour, indicative of an antidepressant
response, which was partially reversed by coadministration of AM251.
No effect of URB597 administration or any effect following the
administration of AM251 alone was, however, observed. These data
indicate that activation of CB1 receptors in the dentate gyrus of
the hippocampus results in an antidepressant-like response.
Collectively, these data highlight the potential importance of
changes in the hippocampal endocannabinoid system following stress
or antidepressant treatment with respect to the manifestation and/or
treatment of depression.
http://stroke.ahajournals.org/cgi/content/abstract/36/5/1071 http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12850548&dopt=Citation http://www.pnas.org/cgi/content/full/95/14/8268 http://linkinghub.elsevier.com/retrieve/pii/S0920996404003986 The endocannabinoid system exerts an important neuromodulatory function in different brain areas and is also known to be involved in the regulation of neural cell fate. Thus, CB(1) cannabinoid receptors are neuroprotective in different models of brain injury, and their expression is altered in various neurodegenerative diseases. Recent findings have demonstrated the presence of a functional endocannabinoid system in neural progenitor cells that participates in the regulation of cell proliferation and differentiation. In this Research Update, the authors address the experimental evidence regarding the regulatory role of cannabinoids in neurogenesis and analyze them in the context of those pathological disorders in which cannabinoid function and altered neuronal or glial generation is most relevant, for example, stroke and multiple sclerosis. --- (Knockout means it was genetically
removed) Pharmacological studies suggest a role for CB1 cannabinoid receptors (CB1R) in regulating neurogenesis in the adult brain. To investigate this possibility, we measured neurogenesis by intraperitoneal injection of bromodeoxyuridine (BrdU), which labels newborn neurons, in wild-type and CB1R-knockout (CB1R-KO) mice. CB1R-KO mice showed reductions in the number of BrdU-labeled cells to approximately 50% of wild-type (WT) levels in dentate gyrus and subventricular zone (SVZ), suggesting that CB1R activation promotes neurogenesis. To test this further, WT mice were given the CB1R antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboximide hydrochloride (SR141716A) before measuring neurogenesis with BrdU. SR141716A paradoxically increased the number of BrdU-labeled cells by approximately 50% in SVZ; another CB1R antagonist, 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-1-piperidinyl-1H-pyrazole-3-carboxamide (AM251), had a similar effect. To investigate this discrepancy, SR141716A was given to CB1R-KO mice, in which it still stimulated neurogenesis, indicating involvement of a non-CB1 receptor. Action at one such non-CB1, SR141716A-sensitive site, the VR1 vanilloid receptor, was tested by administering SR141716A to VR1-KO mice, in which the ability of SR141716A to enhance neurogenesis was abolished. Thus, CB1 and VR1 receptors both seem to have roles in regulating adult neurogenesis. --- http://www.ncbi.nlm.nih.gov/pubmed/16224541?ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum The hippocampal dentate gyrus in the adult mammalian brain contains neural stem/progenitor cells (NS/PCs) capable of generating new neurons, i.e., neurogenesis. Most drugs of abuse examined to date decrease adult hippocampal neurogenesis, but the effects of cannabis (marijuana or cannabinoids) on hippocampal neurogenesis remain unknown. This study aimed at investigating the potential regulatory capacity of the potent synthetic cannabinoid HU210 on hippocampal neurogenesis and its possible correlation with behavioral change. We show that both embryonic and adult rat hippocampal NS/PCs are immunoreactive for CB1 cannabinoid receptors, indicating that cannabinoids could act on CB1 receptors to regulate neurogenesis. This hypothesis is supported by further findings that HU210 promotes proliferation, but not differentiation, of cultured embryonic hippocampal NS/PCs likely via a sequential activation of CB1 receptors, G(i/o) proteins, and ERK signaling. Chronic, but not acute, HU210 treatment promoted neurogenesis in the hippocampal dentate gyrus of adult rats and exerted anxiolytic- and antidepressant-like effects. X-irradiation of the hippocampus blocked both the neurogenic and behavioral effects of chronic HU210 treatment, suggesting that chronic HU210 treatment produces anxiolytic- and antidepressant-like effects likely via promotion of hippocampal neurogenesis. --- http://www.ncbi.nlm.nih.gov/pubmed/16037095?ordinalpos=50&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum The discovery of multipotent neural progenitor (NP) cells has provided strong support for the existence of neurogenesis in the adult brain. However, the signals controlling NP proliferation remain elusive. Endocannabinoids, the endogenous counterparts of marijuana-derived cannabinoids, act as neuromodulators via presynaptic CB1 receptors and also control neural cell death and survival. Here we show that progenitor cells express a functional endocannabinoid system that actively regulates cell proliferation both in vitro and in vivo. Specifically, NPs produce endocannabinoids and express the CB1 receptor and the endocannabinoid-inactivating enzyme fatty acid amide hydrolase (FAAH). CB1 receptor activation promotes cell proliferation and neurosphere generation, an action that is abrogated in CB1-deficient NPs. Accordingly, proliferation of hippocampal NPs is increased in FAAH-deficient mice. Our results demonstrate that endocannabinoids constitute a new group of signaling cues that regulate NP proliferation and thus open novel therapeutic avenues for manipulation of NP cell fate in the adult brain. ---
From the Department of Neuropharmacology (K.M., K.H., N.E., K.I., M.F.), Faculty of Pharmaceutical Sciences, and Advanced Materials Institute (K.I., M.F.), Fukuoka University, Japan; Department of Obstetrics and Gynecology (T.I.), Miyazaki Medical College, University of Miyazaki, Japan; Department of Medical Physics (K.A.), School of Allied Health Sciences, Faculty of Medicine, Osaka University, Japan; and Department of Drug Safety Evaluation (K.A.), Developmental Research Laboratories, Shionogi and Co, Ltd, Osaka, Japan. Background and Purpose— Cannabidiol has been reported to be a neuroprotectant, but the neuroprotective mechanism of cannabidiol remains unclear. We studied the neuroprotective mechanism of cannabidiol in 4-hour middle cerebral artery (MCA) occlusion mice. Methods— Male MCA occluded mice were treated with cannabidiol, abnormal cannabidiol, anandamide, methanandamide, cannabidiol plus capsazepine, and cannabidiol plus WAY100135 before and 3 hours after MCA occlusion. The infarct size was determined after 24 hours (2,3,5-triphenyltetrazolium chloride staining). Cerebral blood flow (CBF) was measured at, before and 1, 2, 3, and 4 hours after MCA occlusion. Results— Cannabidiol significantly reduced the infarct volume induced by MCA occlusion in a bell-shaped curve. Similarly, abnormal cannabidiol but not anandamide or methanandamide reduced the infarct volume. Moreover, the neuroprotective effect of cannabidiol was inhibited by WAY100135, a serotonin 5-hydroxytriptamine1A (5-HT1A) receptor antagonist but not capsazepine a vanilloid receptor antagonist. Cannabidiol increased CBF to the cortex, and the CBF was partly inhibited by WAY100135 in mice subjected to MCA occlusion. Conclusions— Cannabidiol and abnormal cannabidiol reduced the infarct volume. Furthermore, the neuroprotective effect of cannabidiol was inhibited by WAY100135 but not capsazepine, and the CBF increased by cannabidiol was partially reversed by WAY100135. These results suggested that the neuroprotective effect of cannabidiol may be related to the increase in CBF through the serotonergic 5-HT1A receptor. --- http://www.ncbi.nlm.nih.gov/pubmed/16566907?ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum Cannabinoid CB1 receptors
are the most abundant G-protein-coupled receptors in the brain. Its
presynaptic location suggests a role for cannabinoids in modulating
the release of neurotransmitters from axon terminals by retrograde
signaling. The neuroprotective effects of cannabinoid agonists in
animal models of ischemia, seizures, hypoxia, Multiple Sclerosis,
Huntington and Parkinson disease have been demonstrated in several
reports. The proposed mechanism for the neuroprotection ranges from
antioxidant effects, reduction of microglial activation and
anti-inflammatory reaction to receptor-mediated reduction of
glutamate release. In the present work, we analyzed the
morphological changes induced by a chronic treatment with the
synthetic cannabinoid receptor agonist, WIN 55,212-2, in four brain
regions where the CB1 cannabinoid receptor is present in high
density: the CA1 hippocampal area, corpus striatum, cerebellum and
frontal cortex. After a twice-daily treatment for 14 days with the
cannabinoid receptor agonist (3 mg/kg sc, each dose) to male Wistar
rats (150-170 g), the expression of neurofilaments (Nf-160 and
Nf-200), microtubule-associated protein-2 (MAP-2), synaptophysin
(Syn) and glial fibrillary acidic protein (GFAP) was studied by
immunohistochemistry and digital image analysis. Ultrastructural
study of the synapses was done using electron microscopy. After the
treatment, a significant increase in the expression of neuronal
cytoskeletal proteins (Nf-160, Nf-200, MAP-2) was observed, but we
did not find changes in the expression of GFAP, the main astroglial
cytoskeletal protein. In cerebellum, there was an increase in Syn
expression and in the number of synaptic vesicles, while, in the
hippocampus, an increase in the Syn expression and in the thickness
of the postsynaptic densities was observed. The results obtained
from these studies provide evidences on the absence of astroglial
reaction and a sprouting phenomena induced by the WIN treatment that
might be a key contributor to the long-term neuroprotective effects
observed after cannabinoid treatments in different models of central
nervous system (CNS) injury reported in the
literature. | |||
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