Tag Archives: endocannabinoids

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 endogenous cannabinoid system and the treatment of marijuana dependence.

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Abstract

“The active principle of marijuana, Delta9-tetrahydrocannabinol (Delta9-THC), exerts its pharmacological effects by binding to selective receptors present on the membranes of neurons and other cells. These cannabinoid receptors are normally engaged by a family of lipid mediators, called endocannabinoids, which are thought to participate in the regulation of a diversity of brain functions, including pain, mood, appetite and memory. Marijuana use may lead to adaptive changes in endocannabinoid signaling, and these changes might contribute to effects of marijuana as well as to the establishment of marijuana dependence. In the present article, I outline current views on how endocannabinoid substances are produced, released, and deactivated in the brain. In addition, I review recent progress on the development of pharmacological agents that interfere with endocannabinoid deactivation and discuss their potential utility in the treatment of marijuana dependence and other aspects of drug abuse.”

http://www.ncbi.nlm.nih.gov/pubmed/15464150

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/

Cannabinoids reduce symptoms of Tourette’s syndrome.

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Abstract

“Currently, the treatment of Tourette’s syndrome (TS) is unsatisfactory. Therefore, there is expanding interest in new therapeutical strategies. Anecdotal reports suggested that the use of cannabis might improve not only tics, but also behavioural problems in patients with TS. A single-dose, cross-over study in 12 patients, as well as a 6-week, randomised trial in 24 patients, demonstrated that Delta9-tetrahydrocannabinol (THC), the most psychoactive ingredient of cannabis, reduces tics in TS patients. No serious adverse effects occurred and no impairment on neuropsychological performance was observed. If well-established drugs either fail to improve tics or cause significant adverse effects, in adult patients, therapy with Delta9-THC should be tried. At present, it remains unclear whether herbal cannabis, different natural or synthetic cannabinoid CB1-receptor agonists or agents that interfere with the inactivation of endocannabinoids, may have the best adverse effect profile in TS.”

http://www.ncbi.nlm.nih.gov/pubmed/14521482

Tourette’s syndrome.

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Abstract

“Tourette’s syndrome (TS) is a chronic disorder characterized by motor and vocal tics and a variety of associated behaviour disorders. Because current therapy is often unsatisfactory, there is expanding interest in new therapeutic strategies that are more effective, cause less side effects and ameliorate not only tics but also behavioural problems. From anecdotal reports and preliminary controlled studies it is suggested that – at least in a subgroup of patients – cannabinoids are effective in the treatment of TS. While most patients report beneficial effects when smoking marijuana (Cannabis sativa L.), available clinical trials have been performed using oral Δ⁹-tetrahydrocannabinol (THC). In otherwise treatment-resistant TS patients, therefore, therapy with THC should not be left unattempted. To date, it is unknown whether other drugs that interact with the endocannabinoid receptor system might be more effective in the treatment of TS than smoked marijuana or pure THC. Since it has been suggested that abnormalities within the endocannabinoid receptor system might underlie TS pathophysiology, it would be of interest to investigate the effect of substances that for example bind more selectively to the central cannabinoid receptor or inhibit the uptake or the degradation of different endocannabinoids.”

http://www.ncbi.nlm.nih.gov/pubmed/21104394

Plant, synthetic, and endogenous cannabinoids in medicine.

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Abstract

“Although used for more than 4000 years for recreational and medicinal purposes, Cannabis and its best-known pharmacologically active constituents, the cannabinoids, became a protagonist in medical research only recently. This revival of interest is explained by the finding in the 1990s of the mechanism of action of the main psychotropic cannabinoid, Delta9-tetrahydrocannabinol (THC), which acts through specific membrane receptors, the cannabinoid receptors. The molecular characterization of these receptors allowed the development of synthetic molecules with cannabinoid and noncannabinoid structure and with higher selectivity, metabolic stability, and efficacy than THC, as well as the development of antagonists that have already found pharmaceutical application. The finding of endogenous agonists at these receptors, the endocannabinoids, opened new therapeutic possibilities through the modulation of the activity of cannabinoid receptors by targeting the biochemical mechanisms controlling endocannabinoid tissue levels.”

http://www.ncbi.nlm.nih.gov/pubmed/16409166

Phytocannabinoids and endocannabinoids.

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“Progress in understanding the molecular mechanisms of cannabis action was made after discovery of cannabinoid receptors in the brain and the finding of endogenous metabolites with affinity to them. Activation of cannabinoid receptors on synaptic terminals results in regulation of ion channels, neurotransmitter release and synaptic plasticity

. Neuromodulation of synapses by the cannabinoids is proving to have a wide range of functional effects, making them potential targets as medical preparations in a variety of illnesses, including some mental disorders and neurodegenerative illnesses. Cannabis contains a large amount of substances with affinity for the cannabinoid receptors. The endocannabinoids are a family of lipid neurotransmitters that engage the same membrane receptors targeted by tetrahydrocannabinol and that mediate retrograde signal from postsynaptic neurons to presynaptic ones.

 Discovery of endogenous cannabinoids and studies of the physiological functions of the cannabinoid system in the brain and body are producing a number of important findings about the role of membrane lipids and fatty acids in nerve signal transduction. Plant, endogenous and synthetic cannabinoids are using in these studies. The role of lipid membranes in the cannabinoid system follows from the fact that the source and supply of endogenous cannabinoids are derived from arachidonic acid, an important membrane constituent

. The study of structure-activity relationships of molecules which influence the cannabinoid system in the brain and body is crucial in search of medical preparations with the therapeutic effects of the phytocannabinoids without the negative effects on cognitive function attributed to cannabis.”

http://www.ncbi.nlm.nih.gov/pubmed/19630737

[The mechanism of action of cannabis and cannabinoids].

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Abstract

“The effect of cannabis can be explained on the basis of the function of the cannabinoid receptor system, which consists of CB receptors (CB1, CB2), endoligands to activate these receptors and an enzyme–fatty acid amidohydrolase–to metabolize the endoligands. The endoligands of the cannabinoid receptor system are arachidonic acid-like substances, and are called endocannabinoids. Indications exist that the body also contains arachidonic acid-like substances that inhibit fatty acid amido hydrolase. Various cannabinoids have diverse effects on the receptors, functioning as agonists, antagonists or partial antagonists, as well as affecting the vanilloid receptor. Many known effects of cannabis can be explained on the basis of this mechanism of action as can the use of cannabis in various conditions including multiple sclerosis, Parkinson’s disease, glaucoma, nausea, vomiting and rheumatoid arthritis.”

http://www.ncbi.nlm.nih.gov/pubmed/16463612

Cannabis and cannabinoids: pharmacology and rationale for clinical use.

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Abstract

“It is now known that there are at least two types of cannabinoid receptors. These are CB1 receptors, present mainly on central and peripheral neurones, and CB2 receptors, present mainly on immune cells. Endogenous cannabinoid receptor agonists (‘endocannabinoids’) have also been identified. The discovery of this ‘endogenous cannabinoid system’ has led to the development of selective CB1 and CB2 receptor ligands and fueled renewed interest in the clinical potential of cannabinoids. Two cannabinoid CB1 receptor agonists are already used clinically, as antiemetics or as appetite stimulants. These are D 9 – tetrahydrocannabinol (THC) and nabilone. Other possible uses for CB1 receptor agonists include the suppression of muscle spasm/spasticity associated with multiple sclerosis or spinal cord injury, the relief of chronic pain and the management of glaucoma and bronchial asthma. CB1 receptor antagonists may also have clinical applications, e. g. as appetite suppressants and in the management of schizophrenia or disorders of cognition and memory. So too may CB2 receptor ligands and drugs that activate cannabinoid receptors indirectly by augmenting endocannabinoid levels at cannabinoid receptors. When taken orally, THC seems to undergo variable absorption and to have a narrow ‘therapeutic window’ (dose range in which it is effective without producing significant unwanted effects). This makes it difficult to predict an oral dose that will be both effective and tolerable to a patient and indicates a need for better cannabinoid formulations and modes of administration. For the therapeutic potential of cannabis or CB1 receptor agonists to be fully exploited, it will be important to establish objectively and conclusively (a) whether these agents have efficacy against selected symptoms that is of clinical significance and, if so, whether the benefits outweigh the risks, (b) whether cannabis has therapeutic advantages over individual cannabinoids, (c) whether there is a need for additional drug treatments to manage any of the disorders against which cannabinoids are effective, and (d) whether it will be possible to develop drugs that have reduced psychotropic activity and yet retain the ability to act through CB1 receptors to produce their sought-after effects.”

http://www.ncbi.nlm.nih.gov/pubmed/10575283

Pharmacology of cannabinoid receptor ligands.

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Abstract

“Mammalian tissues contain at least two types of cannabinoid receptor, CB1 and CB2, both coupled to G proteins. CB1 receptors are expressed mainly by neurones of the central and peripheral nervous system whereas CB2 receptors occur in certain non-neuronal tissues, particularly in immune cells. The existence of endogenous ligands for cannabinoid receptors has also been demonstrated. The discovery of this endogenous cannabinoid system has been paralleled by a renewed interest in possible therapeutic applications of cannabinoids, for example in the management of pain and in the suppression of muscle spasticity/spasm associated with multiple sclerosis or spinal cord injury. It has also prompted the development of a range of novel cannabinoid receptor ligands, including several that show marked selectivity for CB1 or CB2 receptors. This review summarizes current knowledge about the in vitro pharmacological properties of important CB1 and CB2 receptor ligands. Particular attention is paid to the binding properties of these ligands, to the efficacies of cannabinoid receptor agonists, as determined using cyclic AMP or [35S]GTPgammaS binding assays, and to selected examples of how these pharmacological properties can be influenced by chemical structure. The in vitro pharmacological properties of ligands that can potently and selectively oppose the actions of CB1 or CB2 receptor agonists are also described. When administered by themselves, some of these ligands produce effects in certain tissue preparations that are opposite in direction to those produced by cannabinoid receptor agonists and the possibility that the ligands producing such inverse cannabimimetic effects are inverse agonists rather than pure antagonists is discussed.”

http://www.ncbi.nlm.nih.gov/pubmed/10469884