Category Archives: Endocannabinoid System

Involvement of the endocannabinoid system in drug addiction.

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Abstract

“Recent studies have shown that the endocannabinoid system is involved in the common neurobiological mechanism underlying drug addiction. This system participates in the primary rewarding effects of cannabinoids, nicotine, alcohol and opioids, through the release of endocannabinoids in the ventral tegmental area. Endocannabinoids are also involved in the motivation to seek drugs by a dopamine-independent mechanism, demonstrated for psychostimulants and opioids. The endocannabinoid system also participates in the common mechanisms underlying relapse to drug-seeking behaviour by mediating the motivational effects of drug-related environmental stimuli and drug re-exposure. In agreement, clinical trials have suggested that the CB(1) cannabinoid antagonist rimonabant can cause smoking cessation. Thus, CB(1) cannabinoid antagonists could represent a new generation of compounds to treat drug addiction.”

http://www.ncbi.nlm.nih.gov/pubmed/16483675

Drug Addiction

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Abstract

“Many drugs of abuse, including cannabinoids, opioids, alcohol and nicotine, can alter the levels of endocannabinoids in the brain. Recent studies show that release of endocannabinoids in the ventral tegmental area can modulate the reward-related effects of dopamine and might therefore be an important neurobiological mechanism underlying drug addiction. There is strong evidence that the endocannabinoid system is involved in drug-seeking behavior (especially behavior that is reinforced by drug-related cues), as well as in the mechanisms that underlie relapse to drug use. The cannabinoid CB1 antagonist/inverse agonist rimonabant has been shown to reduce the behavioral effects of stimuli associated with drugs of abuse, including nicotine, alcohol, cocaine, and marijuana. Thus, the endocannabinoid system represents a promising target for development of new treatments for drug addiction.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3039293/

The endocannabinoid system as a target for the treatment of cannabis dependence

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“Cannabinoid replacement therapy and CB1 receptor antagonism are two potential treatments for cannabis dependence that are currently under investigation. However, abuse liability and adverse side effects may limit the scope of each of these approaches. A potential alternative stems from the recognition that (i) frequent cannabis use may cause an adaptive downregulation of brain endocannabinoid signaling, and (ii) that genetic traits that favor hyperactivity of the endocannabinoid system in humans may decrease susceptibility to cannabis dependence. These findings suggest in turn that pharmacological agents that elevate brain levels of the endocannabinoid neurotransmitters, anandamide and 2-arachidonoylglycerol (2-AG), might alleviate cannabis withdrawal and dependence. One such agent, the fatty-acid amide hydrolase (FAAH) inhibitor URB597, selectively increases anandamide levels in the brain of rodents and primates. Preclinical studies show that URB597 produces analgesic, anxiolytic-like and antidepressant-like effects in rodents, which are not accompanied by overt signs of abuse liability. In this article, we review evidence suggesting that (i) cannabis influences brain endocannabinoid signaling; and (ii) FAAH inhibitors such as URB597 might offer a possible therapeutic avenue for the treatment of cannabis withdrawal.”

“Direct modulation of CB1receptors as a treatment for cannabis dependence”

“Even though, as we have seen above, direct activation of CB1 receptors may yield variable behavioral responses, low-dosage oral Δ9-THC has shown promise in the management of human cannabis withdrawal. The rationale for this approach is that controlled replacement of Δ9-THC for smoked cannabis may reduce the severity of withdrawal symptoms and allow a dependent individual to remain abstinent. Additionally, given that dependent subjects are experienced with cannabis, and Δ9-THC is administered at low doses, administration of the latter is unlikely to result in the anxiety responses observed with inexperienced users or high dosages. Consistent with this idea, two independent clinical studies have shown that low-dose oral Δ9-THC attenuates withdrawal symptom scores and is minimally intoxicating in non-treatment seeking daily cannabis users.””

“Several therapeutic modalities are currently being considered to treat cannabis dependence, including activation or deactivation of CB1receptors. While these stategies show promise in measures of cannabis withdrawal and abstinence, they may also create problems of abuse liability or adverse emotional effects. An additional approach might be to enhance endogenous anandamide signaling using agents that attenuate the deactivation of this endocannabinoid transmitter.”

“Increasing anandamide signaling with deactivation inhibitors, such as the FAAH blocker URB597, potentiates stress coping behaviors in animals, indicating a role for anandamide in physiopathological context of stress-related responses. Similarly, elevation of anandamide in specific brain regions opposes the anhedonic effects of stress and promotes normal positive responses to pleasurable stimuli in rodents. It is reasonable to hypothesize that these effects could act to blunt the negative affect and stress, which is common during cannabis withdrawal, thus allowing cannabis dependent individuals to successfully abstain from drug use.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2647947/

The molecular connections between the cannabinoid system and endometriosis.

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Abstract

“The endocannabinoid system consists of an array of endogenously produced bioactive lipids that activate cannabinoid 1 (CB1) and 2 (CB2) receptors. Alterations of this system have been described in almost every category of disease. These changes can be protective or maladaptive, making the endocannabinoid network an attractive therapeutic target. Little is known about the potential role of endocannabinoids in endometriosis development although this is a topic worthy of further investigation since endocannabinoid modulators have recently been shown to affect specific mechanisms critical to endometriosis establishment and maintenance. A literature review was herein performed with the aim of defining the regulation and function of the endocannabinoid signaling in in vitro and animal models of endometriosis. The components of the endocannabinoid system, CB1 and CB2 receptors and the enzymes N-acylphosphatidylethanolamine-phospholipase D and fatty acid amide hydrolase are differentially regulated throughout the menstrual cycle in the endometrium and are expressed in deep endometriotic nodules and in sensory and sympathetic neurons innervating the lesions. Selective cannabinoid receptor agonists, such as WIN 55212-2, appear to have a favorable action in limiting cell proliferation and in controlling pain symptoms. Conversely, endometrial cell migration tends to be stimulated by receptor agonists. The phosphatidylinositol 3-kinase/Akt and extracellular signal-regulated kinase 1/2 pathways seem to be involved in these processes. However, the underlying mechanisms of action are only just beginning to unfold. Given the complexity of the system, further studies are needed to clarify whether the endocannabinoid system might represent a promising target for endometriosis.”

http://www.ncbi.nlm.nih.gov/pubmed/22923487

Δ(9) -Tetrahydrocannabinol and N-arachidonyl glycine are full agonists at GPR18 receptors and induce migration in human endometrial HEC-1B cells.

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Abstract

“BACKGROUND AND PURPOSE:

Endometriosis is a disorder in which the endometrium forms growths outside the uterus and is associated with chronic pain. Recent evidence suggests that endometrial motility plays a role in the aetiology of endometriosis. The endocannabinoid system regulates cellular migration. Given the growing involvement of the endocannabinoids in reproduction, we investigated the role of the endocannabinoid system in migration of endometrial cells.

EXPERIMENTAL APPROACH:

Migration of the human endometrial HEC-1B cells was assayed. Standard PCR techniques were used to determine the presence of the GPCR, GPR18, in HEC-1B cells, and p44/42 MAPK was assayed in stably transfected HEK293-GPR18 cells to determine receptor specificity for known cannabinoid agonists and antagonists. N-arachidonoyl ethanolamine (AEA) metabolism was measured, using HPLC/MS/MS for lipid analysis.

KEY RESULTS:

AEA, Δ(9) -tetrahydrocannabinol (Δ(9) -THC) and N-arachidonoyl glycine (NAGly) induce migration of HEC-1B cells through cannabinoid CB(1) receptor-independent mechanisms. MAPK activation in HEK293-GPR18 cells revealed novel pharmacology for known CB(1) and CB(2) receptor ligands at GPR18 receptors, including Δ(9) -THC, which activates MAPK at nanomolar concentrations, whereas WIN 55212-2, CP55940, JWH-133 and JWH-015, and arachidonyl-1-hydroxy-2-propylamide (R1-methanandamide) had no effect. Moreover, HEC-1B migration and MAPK activation by NAGly and Δ(9) -THC were antagonized by Pertussis toxin, AM251 and cannabidiol.

CONCLUSIONS AND IMPLICATIONS:

An understanding of the function and regulation of GPR18 and its molecular interactions with endogenous ligands, and how phytocannabinoids play a role with GPR18 signalling is vital if we are to comprehensively assess the function of the cannabinoid signalling system in human health and disease. LINKED ARTICLES: This article is commented on by Alexander, pp. 2411-2413 of this issue and is part of a themed section on Cannabinoids in Biology and Medicine. To view Alexander visit http://dx.doi.org/10.1111/j.1476-5381.2011.01731.x. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-8. To view Part I of Cannabinoids in Biology and Medicine visit http://dx.doi.org/10.1111/bph.2011.163.issue-7.”

http://www.ncbi.nlm.nih.gov/pubmed/21595653

Endocannabinoid involvement in endometriosis

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 “Endometriosis is a disease common in women that is defined by abnormal extrauteral growths of uterine endometrial tissue and associated with severe pain. Partly because how the abnormal growths become associated with pain is poorly understood, the pain is difficult to alleviate without resorting to hormones or surgery, which often produce intolerable side effects or fail to help. Recent studies in a rat model and women showed that sensory and sympathetic nerve fibers sprout branches to innervate the abnormal growths. This situation, together with knowledge that the endocannabinoid system is involved in uterine function and dysfunction and that exogenous cannabinoids were once used to alleviate endometriosis-associated pain, suggests that the endocannabinoid system is involved in both endometriosis and its associated pain. Here, using a rat model, we found that CB1 cannabinoid receptors are expressed on both the somata and fibers of both the sensory and sympathetic neurons that innervate endometriosis’s abnormal growths. We further found that CB1 receptor agonists decrease, whereas CB1 receptor antagonists increase, endometriosis-associated hyperalgesia. Together these findings suggest that the endocannabinoid system contributes to mechanisms underlying both the peripheral innervation of the abnormal growths and the pain associated with endometriosis, thereby providing a novel approach for the development of badly-needed new treatments.”

“These findings implicate involvement of the endocannabinoid system in reproductive function and dysfunction. The endocannabinoid system plays a key role in pain mechanisms, and, previously, cannabinoids were long used by women to alleviate dysmenorrhea.”

“Together the findings suggest that the endocannabinoid system is involved in endometriosis and its associated pain via CB1 receptors and innervation of the ectopic growths. Using the rat model, we performed a combination of immunohistochemical and pharmacological studies to test this hypothesis and assess the endocannabinoid system’s potential as a target for new therapies.”

 Summary and conclusions

“These studies in a rat model of endometriosis provide evidence that endocannabinoids might regulate the innervation of the disease’s abnormal growths and that exogenous cannabinoid agents can be effective in reducing endometriosis symptoms. The fact that CB1 receptor expression is greater in the cysts than healthy uterus from the same rats suggests that treatments to activate CB1 receptors (either directly by CB1 agonists or indirectly by increasing relevant endocannabinoid levels) could be developed with minimal effects on uterine function. Although the rat model parallels many aspects of endometriosis in women, there are of course significant differences. However, when considered together with the past history of successful use of cannabinoids for alleviation of gynecological pains, and insofar as findings in rats can model mechanisms of endometriosis-related signs and symptoms, the present results suggest that approaches targeted at the endocannbinoid system represent a promising new direction for developing badly-needed new treatments for pain suffered by women with endometriosis.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2972363/

[The endogenous cannabinoid system. Therapeutic implications for neurologic and psychiatric disorders].

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Abstract

“For about 5,000 years, cannabis has been used as a therapeutic agent. There has been growing interest in the medical use of cannabinoids. This is based on the discovery that cannabinoids act with specific receptors (CB1 and CB2). CB1 receptors are located in specific brain areas (e.g. cerebellum, basal ganglia, and hippocampus) and CB2 receptors on cells of the immune system. Endogenous ligands of the cannabinoid receptors were also discovered (e.g. anandamids). Many physiologic processes are modulated by the two subtypes of cannabinoid receptor: motor functions, memory, appetite, and pain. These innovative neurobiologic/pharmacologic findings could possibly lead to the use of synthetic and natural cannabinoids as therapeutic agents in various areas. Until now, cannabinoids were used as antiemetic agents in chemotherapy-induced emesis and in patients with HIV-wasting syndrome. Evidence suggests that cannabinoids may prove useful in some other diseases, e.g. movement disorders such as Gilles de la Tourette’s syndrome, multiple sclerosis, and pain. These new findings also explain the acute adverse effects following cannabis use.”

http://www.ncbi.nlm.nih.gov/pubmed/15776259

Delta 9-tetrahydrocannabinol (THC) is effective in the treatment of tics in Tourette syndrome: a 6-week randomized trial.

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“Preliminary studies suggested that delta-9-tetrahydrocannabinol (THC), the major psychoactive ingredient of Cannabis sativa L., might be effective in the treatment of Tourette syndrome (TS).

This study was performed to investigate for the first time under controlled conditions, over a longer-term treatment period, whether THC is effective and safe in reducing tics in TS.

CONCLUSION:

Our results provide more evidence that THC is effective and safe in the treatment of tics. It, therefore, can be hypothesized that the central cannabinoid receptor system might play a role in TS pathology.”

https://www.ncbi.nlm.nih.gov/pubmed/12716250

“Our results provide more evidence that THC is effective and safe in the treatment of tics.” http://www.psychiatrist.com/jcp/article/Pages/2003/v64n04/v64n0417.aspx

Recent developments in the therapeutic potential of cannabinoids.

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Abstract

“OBJECTIVE:

To examine the recent evidence that marijuana and other cannabinoids have therapeutic potential.

METHODS:

Literature published since 1997 was searched using the following terms: cannabinoid, marijuana, THC, analgesia, cachexia, glaucoma, movement, multiple sclerosis, neurological, pain, Parkinson, trial, vomiting. Qualifying clinical studies were randomized, double-blind, and placebo-controlled. Selected open-label studies and surveys are also discussed.

RESULTS:

A total of 15 independent, qualifying clinical trials were identified, of which only three had more than 100 patients each. Two large trials found that cannabinoids were significantly better than placebo in managing spasticity in multiple sclerosis. Patients self-reported greater sense of motor improvement in multiple sclerosis than could be confirmed objectively. In smaller qualifying trials, cannabinoids produced significant objective improvement of tics in Tourette’s disease, and neuropathic pain. A new, non-psychotropic cannabinoid also has analgesic activity in neuropathic pain. No significant improvement was found in levodopa-induced dyskinesia in Parkinson’s Disease or post-operative pain. No difference from active placebo was found for management of cachexia in a large trial. Some immune system parameters changed in HIV-1 and multiple sclerosis patients treated with cannabinoids, but the clinical significance is unknown. Quality of life assessments were made in only three of 15 qualifying clinical trials.

CONCLUSION:

Cannabinoids may be useful for conditions that currently lack effective treatment, such as spasticity, tics and neuropathic pain. New delivery systems for cannabinoids and cannabis-based medicinal extracts, as well as new cannabinoid derivatives expand the options for cannabinoid therapy. More well-controlled, large clinical tests are needed, especially with active placebo.”

http://www.ncbi.nlm.nih.gov/pubmed/15895873

Cannabinoids in medicine: A review of their therapeutic potential.

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“In order to assess the current knowledge on the therapeutic potential of cannabinoids, a meta-analysis was performed through Medline and PubMed up to July 1, 2005. The key words used were cannabis, marijuana, marihuana, hashish, hashich, haschich, cannabinoids, tetrahydrocannabinol, THC, dronabinol, nabilone, levonantradol, randomised, randomized, double-blind, simple blind, placebo-controlled, and human. The research also included the reports and reviews published in English, French and Spanish.

For the final selection, only properly controlled clinical trials were retained, thus open-label studies were excluded. Seventy-two controlled studies evaluating the therapeutic effects of cannabinoids were identified. For each clinical trial, the country where the project was held, the number of patients assessed, the type of study and comparisons done, the products and the dosages used, their efficacy and their adverse effects are described.

 Cannabinoids present an interesting therapeutic potential as antiemetics, appetite stimulants in debilitating diseases (cancer and AIDS), analgesics, and in the treatment of multiple sclerosis, spinal cord injuries, Tourette’s syndrome, epilepsy and glaucoma.”

http://www.ncbi.nlm.nih.gov/pubmed/16540272