Role of cannabinoids and endocannabinoids in cerebral ischemia

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“The human costs of stroke are very large and growing; it is the third largest cause of death in the United States and survivors are often faced with loss of ability to function independently. There is a large need for therapeutic approaches that act to protect neurons from the injury produced by ischemia and reperfusion… 

 Overall, the available data suggest that inhibition of CB1 receptor activation together with increased CB2 receptor activation produces beneficial effects.

These studies support the hypothesis that activation of the CB1 receptor by highly efficacious, exogenous agonists during the acute phase of ischemia decreases the likelihood of the occurrence of a detrimental event at the time of ischemia and thereby reduces the amount of infarction and neuronal death long-term… A protective role of the CB1 receptor is also supported by studies…

While it is possible that the ECS will be added to the long list of neuroprotective agents that show promise in animals and do not work in humans, there are a few reasons to be optimistic about this class of drugs. First, many of the other agents did not work because they do not cross the blood brain barrier. While the considerable lipophilicity of the cannabinoids poses its own set of problems, these drugs have no problems entering the brain. Second, the ECS is multifactorial and could “cover” multiple biochemical pathways in a single drug. Third, manipulations of the ECS has been shown to be beneficial in several preclinical models. Only time and further research will answer the most important question, are the cannabinoids of therapeutic benefit in humans suffering from stroke?”

Full text: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2581413/

 

Endocannabinoid regulation of matrix metalloproteinases: implications in ischemic stroke.

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“Stroke is a major cause of morbidity and mortality and follows heart disease and cancer as the third leading cause of death in Western societies. Despite many advances in stroke research and pharmacotherapy, clinical treatment of this debilitating disorder is still inadequate.

Recent findings from several laboratories have identified the endocannabinoid signaling pathway, comprised of the endocannabinoid agonist anandamide and its pharmacological targets, CB1 and CB2 cannabinoid receptors and associated anandamide receptors, as a physiological system with capacity to mitigate cardiovascular and cerebrovascular disorders through neuronal and endothelial actions. Variability in experimental stroke models and modes of outcome evaluation, however, have provoked controversy regarding the precise roles of endocannabinoid signals in mediating neural and/or vascular protection versus neurovascular damage.

Clinical trials of the CB1 antagonist rimonabant demonstrate that modulation of endocannabinoid signaling during metabolic regulation of vascular disorders can significantly impact clinical outcomes, thus providing strong argument for therapeutic utility of endocannabinoids and/or cannabinoid receptors as targets for therapeutic intervention in cases of stroke and associated vascular disorders.

The purpose of this review is to provide updated information from basic science and clinical perspectives on endocannabinoid ligands and their effects in the pathophysiologic genesis of stroke. Particular emphasis will be placed on the endocannabinoids anandamide and 2-arachidonylglycerol and CB1 receptor-mediated mechanisms in the neurovascular unit during stroke pathogenesis. Deficiencies in our knowledge of endocannabinoids in the etiology and pathogenesis of stroke, caveats and limitations of existing studies, and future directions for investigation will be addressed.”

http://www.ncbi.nlm.nih.gov/pubmed/17979695

Endocannabinoids and cannabinoid receptors in ischaemia–reperfusion injury and preconditioning

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“This review is aimed to discuss the role of endocannabinoids and CB receptors in various forms of I/R injury (myocardial, cerebral, hepatic and circulatory shock) and preconditioning, and to delineate the evidence supporting the therapeutic utility of selective CB2 receptor agonists, which are devoid of psychoactive effects, as a promising new approach to limit I/R-induced tissue damage.

In this review, we will discuss the triggers and sources of endocannabinoid production during various forms of I/R injury (myocardial, cerebral, hepatic and retinal ischaemia, and circulatory shock) and preconditioning, as well as the diverse role of these novel mediators and their receptors in these processes. We will also overview the accumulating evidence obtained through the use of various synthetic CB1/CB2 receptor ligands, with particular focus on the novel role of CB2 receptors, suggesting that the modulation of the endocannabinoid system can be therapeutically exploited in various forms of I/R injury.

Cerebral I/R (stroke)

The first evidence for the neuroprotective effect of CBs came from the stroke research field from studies using synthetic non-psychotropic CB Dexanabinol/HU-211, which exerted its beneficial effects through CB1/CB2-independent mechanisms.

Collectively, it appears that both CB1 agonists and antagonists may afford neuroprotective effects against cerebral I/R…

There is considerable interest in the development of selective CB2 receptor agonists, which are devoid of psychoactive properties of CB1 agonists, for various inflammatory disorders. Further studies should also establish the therapeutic window of protection during the reperfusion phase with the currently available CB2 receptor agonists, and new compounds should also be designed with better in vivo bioavailability, to devise clinically relevant treatment strategies against various forms of I/R. Nevertheless, the recently observed beneficial effects of CB2 receptor agonists in hepatic and other forms of I/R, coupled with the absence of psychoactive properties, and antifibrotic effects of CB2 receptor in the liver suggest that this approach may represent a novel promising strategy against various forms of I/R injury and other inflammatory disorders.”

Full text: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2219536/

CB1 cannabinoid receptor induction in experimental stroke.

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“Cannabinoids protect cortical neurons from ischemic injury by interacting with CB1 receptors. Because a variety of neuroprotective genes are induced in cerebral ischemia, we examined the effect of experimental stroke, produced by 20 minutes of middle cerebral artery occlusion in rats, on CB1 receptor expression.

Western blotting and immunohistochemistry showed that CB1 expression on neurons was increased in the arterial boundary zone of the cortical mantle, beginning by 2 hours and persisting for 72 hours or more after ischemia.

These findings are consistent with a neuroprotective role for endogenous cannabinoid signaling pathways and with a potential therapeutic role in stroke for drugs that activate CB1 receptors.”

http://www.ncbi.nlm.nih.gov/pubmed/10939579

Increased Severity of Stroke in CB1 Cannabinoid Receptor Knock-Out Mice

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“These findings indicate that endogenous cannabinoid signaling pathways protect mice from ischemic stroke by a mechanism that involves CB1 receptors, and suggest that both blood vessels and neurons may be targets of this protective effect.

 Endogenous cannabinoid signaling pathways have been implicated in protection of the brain from hypoxia, ischemia, and trauma…

Cannabinoids, which include the marijuana constituent Δ9-tetrahydrocannabinol and endogenous cannabinoids (endocannabinoids) produced in the brain, exert many of their effects through the G-protein-coupled CB1 receptor.

Cannabinoids reduce neuronal death from a variety of insults, including excitotoxicity, oxidative stress, hypoxia, ischemic stroke and trauma…

Clinical stroke, which usually results from cerebral ischemia, is a common and frequently incapacitating problem for which satisfactory treatment is generally unavailable. Identifying new endogenous systems that mitigate ischemic brain injury through effects on neurons, blood vessels, or both (such as the endocannabinoid signaling pathway) may help to guide the search for improved therapies.”

Full text: http://www.jneurosci.org/content/22/22/9771.long

Endocannabinoids and obesity.

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“A safe and effective antiobesity drug is needed to combat the global obesity epidemic. The discovery of cannabinoids from medicinal herbs has revealed the endocannabinoid system (ECS) in animals and humans, which regulates various physiological activities such as feeding, thermogenesis, and body weight (BW).

Although cannabinoid receptors 1 (CB1) antagonists have shown antiobesity efficacies in animal models and in the clinic, they failed to establish as a treatment due to their psychological side effects.

 Recent studies indicate that CB1 in various peripheral tissues may mediate some of the therapeutic effects of CB1 antagonists, such as improved lipid and glucose homeostasis.

 It rationalizes the development of compounds with limited brain penetration, for minimizing the side effects while retaining the therapeutic efficacies. A survey of the literature has revealed some controversies about how the ECS affects obesity. This review summarizes the research progresses and discusses some future perspectives.”

http://www.ncbi.nlm.nih.gov/pubmed/23374723

Skin Cancer Patient Says Oil From Medical Marijuana Is A Cure

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“A Ferndale man claims he’s found a cure for his cancer and it’s now legal in Michigan.”

%name Skin Cancer Patient Says Oil From Medical Marijuana Is A Cure.

“WWJ’s Sandra McNeill spoke with Michael McShane who claims he’s been using a topical oil made from medical marijuana on the skin cancer on his forehead and in just over two months it’s nearly gone.

“I’ve got biopsies, chart notes, photographs … in about three weeks I’m going to go back  and really wrap this part of the case up,” said McShane. “It’s made the same way a lot of the fragrances and perfumes are made, and the oil is applied, in my case, directly to the skin, and within 10 weeks my cancer is gone.

“From a topical standpoint I don’t experience any euphoria,” said McShane.

McShane freely admits that he has smoked marijuana since he was in his teens, “It went from a party to a cure for cancer,” he said.”

Read more: http://detroit.cbslocal.com/2011/08/29/skin-cancer-patient-says-oil-from-medical-marijuana-is-a-cure/

Cannabinoid receptors as novel targets for the treatment of melanoma

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“Melanoma causes the greatest number of skin cancer-related deaths worldwide. Here, we evaluated the efficacy of cannabinoid receptor agonists, a new family of potential antitumoral compounds, at skin melanoma. Human melanomas and melanoma cell lines express CB1 and CB2 cannabinoid receptors. Activation of these receptors decreased growth, proliferation, angiogenesis and metastasis, and increased apoptosis, of melanomas in mice. Cannabinoid antimelanoma activity was independent of the immune status of the animal, could be achieved without overt psychoactive effects and was selective for melanoma cells vs. normal melanocytes.

Cannabinoid antiproliferative action on melanoma cells…

 These findings may contribute to the design of new chemotherapeutic strategies for the management of melanoma.

 …the present report, together with the implication of CB2 receptors in the control of processes such as pain initiation, emesis, and inflammation, opens the attractive possibility of finding cannabinoid-based therapeutic strategies devoid of nondesired psychotropic side effects.

Specifically, the antiproliferative effect of cannabinoids reported here may set the basis for a new therapeutic approach for the treatment of malignant melanoma.”

Full text: http://www.fasebj.org/content/20/14/2633.long

Inhibition of skin tumor growth and angiogenesis in vivo by activation of cannabinoid receptors

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“Cannabinoids inhibit skin tumor growth in vivo. Here we show that the CB1 and the CB2 receptor are expressed in normal skin and skin tumors of mice and humans. In cell culture experiments pharmacological activation of cannabinoid receptors induced the apoptotic death of tumorigenic epidermal cells, whereas the viability of nontransformed epidermal cells remained unaffected. Local administration of the mixed CB1/CB2 agonist WIN-55,212-2 or the selective CB2 agonist JWH-133 induced a considerable growth inhibition of malignant tumors generated by inoculation of epidermal tumor cells into nude mice. Cannabinoid-treated tumors showed an increased number of apoptotic cells.

 

Cannabinoids, the active components of Cannabis sativa linnaeus (marijuana)…

Marijuana and its derivatives have been used in medicine for many centuries, and currently there is a renaissance in the study of the therapeutic effects of cannabinoids… cannabinoids may be potential antitumoral agents owing to their ability to induce the regression of various types of tumors, including lung adenocarcinoma, glioma, and thyroid epithelioma in animal models.

This background prompted us to explore whether (a) the skin and skin tumors express cannabinoid receptors; (b) cannabinoid receptor activation exerts a growth-inhibiting action on skin tumors in vivo; and (c) inhibition of angiogenesis is implicated in the anti-tumoral effect of cannabinoids.

Our data show that (a) CB1 and CB2 receptors are present in the skin and skin tumors; (b) local cannabinoid receptor activation induces the regression of skin tumors in vivo; and (c) at least two mechanisms may be involved in this action: direct apoptosis of tumor cells and inhibition of tumor angiogenesis.

These results support a new therapeutic approach for the treatment of skin tumors.”

Full text: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC151833/

Revisiting CB1 receptor as drug target in human melanoma.

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“Previous studies have indicated the antitumoral effect of human melanocytes, human melanoma cell lines expressing CB1 receptor (CB1), and of the peritumoral administration of endocannabinoids. In the present study, we systematically screened several human melanoma cell lines for the expression of CNR1 and demonstrated transcription of the authentic gene. The product of CNR1, the CB1 protein, was found localized to the cell membrane as well as to the cytoskeleton. Further, the studied human melanoma cell lines expressed functional CB1 since physiological and synthetic ligands, anandamide (AEA), Met-F-AEA, ACEA and AM251 showed a wide range of biological effects in vitro, for example anti-proliferative, proapoptotic and anti-migratory. More importantly, our studies revealed that systemic administration of a stable CB1 agonist, ACEA, into SCID mice specifically inhibited liver colonization of human melanoma cells.

Since therapeutic options for melanoma patients are still very limited, the endocannabinoid-CB1 receptor system may offer a novel target.”

http://www.ncbi.nlm.nih.gov/pubmed/22447182