Tag Archives: Cannabinoids

Endocannabinoid release from midbrain dopamine neurons: a potential substrate for cannabinoid receptor antagonist treatment of addiction.

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Abstract

“Substantial evidence suggests that all commonly abused drugs act upon the brain reward circuitry to ultimately increase extracellular concentrations of the neurotransmitter dopamine in the nucleus accumbens and other forebrain areas. Many drugs of abuse appear to increase dopamine levels by dramatically increase the firing and bursting rates of dopamine neurons located in the ventral mesencephalon. Recent clinical evidence in humans and behavioral evidence in animals indicate that cannabinoid receptor antagonists such as SR141716A (Rimonabant) can reduce the self-administration of, and craving for, several commonly addictive drugs. However, the mechanism of this potentially beneficial effect has not yet been identified. We propose, on the basis of recent studies in our laboratory and others, that these antagonists may act by blocking the effects of endogenously released cannabinoid molecules (endocannabinoids) that are released in an activity- and calcium-dependent manner from mesencephalic dopamine neurons. It is hypothesized that, through the antagonism of cannabinoid CB1 receptors located on inhibitory and excitatory axon terminals targeting the midbrain dopamine neurons, the effects of the endocannabinoids are occluded. The data from these studies therefore suggest that the endocannabinoid system and the CB1 receptors located in the ventral mesencephalon may play an important role in regulating drug reward processes, and that this substrate is recruited whenever dopamine neuron activity is increased.”

http://www.ncbi.nlm.nih.gov/pubmed/15878779

The role of CB1 receptors in psychostimulant addiction.

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Abstract

“Recent studies have implicated the endocannabinoid (eCB) system in the neuronal mechanisms underlying substance dependence. Here, we review results of studies using cannabinoid receptor subtype 1 (CB1) knockout mice as well as CB1 antagonists to elucidate the role of this neurotransmitter system in psychostimulant addiction. The overall picture is that CB1 receptors appear not to be involved in psychostimulant reward, nor in the development of dependence to such substances. In contrast, the eCB system appears to play a role in the persistence of psychostimulant addiction. In particular, CB1 receptors have been found to play a cardinal role in mediating reinstatement of previously extinguished drug-seeking behavior upon re-exposure to the drug or drug-associated cues. The anatomical loci as well as the neuronal mechanisms of the relapse-preventing effects of CB1 antagonists are still poorly understood, although interactions of the eCB system with afferent glutamatergic and possibly dopaminergic projections to the nucleus accumbens are most likely involved. In addition, CB1 receptors seem to modulate drug-related memories, in line with the hypothesized role of the eCB system in memory-related plasticity. Together, these findings suggest that modulators of the eCB system represent a promising novel type of therapy to treat drug addiction.”

http://www.ncbi.nlm.nih.gov/pubmed/18482432

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/

Safety and side effects of cannabidiol, a Cannabis sativa constituent.

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“Cannabidiol (CBD), a major nonpsychotropic constituent of Cannabis, has multiple pharmacological actions, including anxiolytic, antipsychotic, antiemetic and anti-inflammatory properties. However, little is known about its safety and side effect profile in animals and humans. This review describes in vivo and in vitro reports of CBD administration across a wide range of concentrations, based on reports retrieved from Web of Science, Scielo and Medline. The keywords searched were “cannabinoids”, “cannabidiol” and “side effects”. Several studies suggest that CBD is non-toxic in non-transformed cells and does not induce changes on food intake, does not induce catalepsy, does not affect physiological parameters (heart rate, blood pressure and body temperature), does not affect gastrointestinal transit and does not alter psychomotor or psychological functions. Also, chronic use and high doses up to 1,500 mg/day of CBD are reportedly well tolerated in humans. Conversely, some studies reported that this cannabinoid can induce some side effects, including inhibition of hepatic drug metabolism, alterations of in vitro cell viability, decreased fertilization capacity, and decreased activities of p-glycoprotein and other drug transporters. Based on recent advances in cannabinoid administration in humans, controlled CBD may be safe in humans and animals. However, further studies are needed to clarify these reported in vitro and in vivo side effects.”

Prescribing cannabis for harm reduction

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“Neuropathic pain affects between 5% and 10% of the US population and can be refractory to treatment. Opioids may be recommended as a second-line pharmacotherapy but have risks including overdose and death. Cannabis has been shown to be effective for treating nerve pain without the risk of fatal poisoning. The author suggests that physicians who treat neuropathic pain with opioids should evaluate their patients for a trial of cannabis and prescribe it when appropriate prior to using opioids. This harm reduction strategy may reduce the morbidity and mortality rates associated with prescription pain medications.”

“Medicine relies upon the principle of, “First, do no harm,” and one might supplement the axiom to read – “First, do no harm, and second, reduce all the harm you can.” “Harm reduction” or “harm minimization” can be defined in the broadest sense as strategies designed to reduce risk or harm. Those harmed may include the individual, others impacted by the harmed person, and society. The substitution of a safer drug for one that is more dangerous is considered harm reduction. Specific examples of HR include prescribing methadone or buprenorphine to replace heroin, prescribing nicotine patches to be used instead of smoking tobacco, and prescribing intranasal naloxone to patients on opioid therapy to be utilized in case of overdose. Substituting cannabis for prescribed opioids may be considered a harm reduction strategy.”

“Under the Federal Controlled Substance Act “marihuana” is illegal and classified as a schedule I substance-meaning it has a high potential for abuse and no accepted medical use. However, sixteen states and the District of Columbia have legalized cannabis for medicinal use and these include Alaska, Arizona, California, Colorado, Delaware, Hawaii, Maine, Michigan, Montana, Nevada, New Jersey, New Mexico, Oregon, Rhode Island, Vermont, and Washington. Each state law differs but all allow physicians to “authorize” or “recommend” cannabis for specific ailments. This “recommendation” affords legal protections for patients to obtain and use medicinal cannabis, and may be considered the “prescription.””

“Cannabis (Cannabis sativa) and the opium poppy (Papaver somniferum) are both ancient plants that have been used medicinally for thousands of years. The natural and synthetic derivatives of opium, including morphine, are called “opioids.”  “Cannabinoids” is the term for a class of compounds within cannabis of which delta-9-tetrahydrocannabinol (THC) is the most familiar. Besides THC, approximately 100 other cannabinoids have been identified including one of special scientific interest called “cannabidiol” (CBD). The human body produces both endogenous cannabinoids (endocannabinoids) and opioids (endorphins) and contains specific receptors for these substances. There is an extensive literature on opioids but far less on cannabis/cannabinoids (CC).”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3295721/

Cannabis as an adjunct to or substitute for opiates in the treatment of chronic pain.

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Abstract

“There is a growing body of evidence to support the use of medical cannabis as an adjunct to or substitute for prescription opiates in the treatment of chronic pain. When used in conjunction with opiates, cannabinoids lead to a greater cumulative relief of pain, resulting in a reduction in the use of opiates (and associated side-effects) by patients in a clinical setting. Additionally, cannabinoids can prevent the development of tolerance to and withdrawal from opiates, and can even rekindle opiate analgesia after a prior dosage has become ineffective. Novel research suggests that cannabis may be useful in the treatment of problematic substance use. These findings suggest that increasing safe access to medical cannabis may reduce the personal and social harms associated with addiction, particularly in relation to the growing problematic use of pharmaceutical opiates. Despite a lack of regulatory oversight by federal governments in North America, community-based medical cannabis dispensaries have proven successful at supplying patients with a safe source of cannabis within an environment conducive to healing, and may be reducing the problematic use of pharmaceutical opiates and other potentially harmful substances in their communities.”

http://www.ncbi.nlm.nih.gov/pubmed/22880540

Antiproliferative Effects of Cannabinoid Agonists on Deep Infiltrating Endometriosis

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“Deep infiltrating endometriosis (DIE) is characterized by chronic pain, hyperproliferation of endometriotic cells and fibrosis. Since cannabinoids are endowed with antiproliferative and antifibrotic properties, in addition to their psychogenic and analgesic effects, cannabinoid agonists have been evaluated in DIE both in vitro and in vivo. The in vitro effects of the cannabinoid agonist WIN 55212-2 were evaluated on primary endometriotic and endometrial stromal and epithelial cell lines extracted from patients with or without DIE. Cell proliferation was determined by thymidine incorporation and production of reactive oxygen species by spectrofluorometry. ERK and Akt pathways were studied by immunoblotting. Immunoblotting of α-smooth muscle actin was studied as evidence of myofibroblastic transformation. The in vivo effects of WIN 55212-2 were evaluated on Nude mice implanted with human deep infiltrating endometriotic nodules. The in vitro treatment of stromal endometriotic cells by WIN 55212-2 decreased cell proliferation, reactive oxygen species production, and α-smooth muscle actin expression. The decrease in cell proliferation induced by WIN 55212-2 was not associated with a decrease in ERK activation, but was associated with the inhibition of Akt activation. WIN 55212-2 abrogated the growth of endometriotic tissue implanted in Nude mice. Cannabinoid agonists exert anti-proliferative effects on stromal endometriotic cells linked to the inhibition of the Akt pathway. These beneficial effects of cannabinoid agonists on DIE have been confirmed in vivo.”

“The cannabinoids are well known for their psychogenic effects and their role in inflammation and immunity. They are also endowed with properties that can be used in the control of three major aspects of DIE: hyperproliferation, fibrosis, and chronic pain. Because of their implication in proliferation, apoptosis, and angiogenesis, the cannabinoids control cell growth. Their antiproliferative effects result from the inhibition of growth factors and the deregulation of such signaling pathways as Ras-Raf-MKKK1-ERK1/2, PI3K-Akt/PKB-mTOR and c-Jun N-terminal kinase-MAPK. These mechanisms have suggested new targets in cancer treatment and also in endometriosis, since endometriotic cells have a hyperproliferative phenotype and pro-angiogenic properties. In addition, several experimental studies have reported an antifibrotic role of cannabinoid agonists. If such antifibrotic effect of cannabinoid agonists could be demonstrated in DIE it would allow a less extensive surgery. Finally, cannabinoids have analgesic properties and have been used for a long time in treating chronic pain.“

“Therefore, we have evaluated the effects of cannabinoid agonists in vitro on cells extracted from biopsies of deep infiltrating endometriosis and in vivo on a mouse model of endometriosis. We conclude from our data that cannabinoid agonists represent a promising approach in the treatment of DIE.”

“In conclusion, WIN 55212-2 has in vitro antiproliferative and antifibrotic effects in deep infiltrating endometriotic cells. The antiproliferative effect is linked to the inactivation of the Akt pathway. The effectiveness of WIN 55212-2 in vitro, confirmed in vivo in a mouse model of DIE, suggests that the cannabinoid agonists represent a promising therapeutic approach in the treatment of DIE.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2993285/

 

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