Tag Archives: cannabinoid receptors

Would some cannabinoids ameliorate symptoms of autism?

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“Cannabidiol (CBD) is a major nonpsychotropic constituent of cannabis sativa, which unlike the other major constituent delta9-tetrahydrocannabinol (delta9-THC), is virtually inactive at both of its central nervous system receptors. In one study, cell-based calcium mobilization and electrophysiological assays were used to identify and characterize several novel cannabinoid TRPV2 agonists in cultured rat dorsal root ganglion neurons. Among these, CBD was found to be the most robust and potent, followed by delta9-THC and cannabinol. Those cannabinoids may, accordingly, possess the ability, due to their action as TRPV2 agonists, to increase the release of both oxytocin and vasopressin enhancing the stimulation of oxytocin receptor and V1a receptors at the same time. CBD displays a plethora of other actions including anticonvulsive, sedative, hypnotic, antipsychotic, anti-inflammatory and neuroprotective properties. CBD and delta9-THC are components of drugs commercialized, in certain countries, as treatments for neuropathic pain, overactive bladder, and spasticity in patients suffering from multiple sclerosis. Thus, despite their action on oxytocin and vasopressin release, CBD and delta9-THC may help in improving symptoms of ASD by their sedative, antipsychotic, anticonvulsant and tranquilizing effects. In addition, the cannabinoid system has already been shown to be implicated in social behavior in rats.
 
The administration of cannabinoids for children and adolescents suffering from ASD is a controversial legal and ethical issue. Instead, those cannabinoids may be tested when administered to animals presenting autistic symptoms. Animal models of autistic symptoms exist especially in rodents that have their oxytocin and/or vasopressin function impaired such as mice or rats lacking the oxytocin or vasopressin gene or one of their receptors]. Whenever cannabinoids were found efficient in animal models of autism, the rationale supporting their efficacy may outweigh their legal and ethical adversities, when administered to children in the setting of randomized controlled studies.”
 

Variation in the human cannabinoid receptor CNR1 gene modulates gaze duration for happy faces.

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  “From an early age, humans look longer at preferred stimuli and also typically look longer at facial expressions of emotion, particularly happy faces. Atypical gaze patterns towards social stimuli are common in autism spectrum conditions (ASC). However, it is unknown whether gaze fixation patterns have any genetic basis. In this study, we tested whether variations in the cannabinoid receptor 1 (CNR1) gene are associated with gaze duration towards happy faces. This gene was selected because CNR1 is a key component of the endocannabinoid system, which is involved in processing reward, and in our previous functional magnetic resonance imaging (fMRI) study, we found that variations in CNR1 modulate the striatal response to happy (but not disgust) faces. The striatum is involved in guiding gaze to rewarding aspects of a visual scene. We aimed to validate and extend this result in another sample using a different technique (gaze tracking).

One of the key molecular systems involved in the functioning of the striatal circuit is the endocannabinoid system. It is a neuropeptidergic circuit involved in reward processing and works in tandem with the mesolimbic dopaminergic system. Expressed selectively in the brain, the cannabinoid receptor 1 (CNR1) is the best-studied molecule of this system.

This finding suggests a role for CNR1 in social reward processing and could have significance for clinical conditions such ASC, which are marked by a deficit in social reward processing as well as atypical responses to facial expressions of emotion.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3155489/

Variations in the human cannabinoid receptor (CNR1) gene modulate striatal responses to happy faces.

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Abstract

“Happy facial expressions are innate social rewards and evoke a response in the striatum, a region known for its role in reward processing in rats, primates and humans. The cannabinoid receptor 1 (CNR1) is the best-characterized molecule of the endocannabinoid system, involved in processing rewards. We hypothesized that genetic variation in human CNR1 gene would predict differences in the striatal response to happy faces. In a 3T functional magnetic resonance imaging (fMRI) scanning study on 19 Caucasian volunteers, we report that four single nucleotide polymorphisms (SNPs) in the CNR1 locus modulate differential striatal response to happy but not to disgust faces. This suggests a role for the variations of the CNR1 gene in underlying social reward responsivity. Future studies should aim to replicate this finding with a balanced design in a larger sample, but these preliminary results suggest neural responsivity to emotional and socially rewarding stimuli varies as a function of CNR1 genotype. This has implications for medical conditions involving hypo-responsivity to emotional and social stimuli, such as autism.”

http://www.ncbi.nlm.nih.gov/pubmed/16623851

[Cannabinoids in the control of pain].

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Abstract

“Hemp (Cannabis sativa L.) has been used since remotes ages as a herbal remedy. Only recently the medical community highlighted the pharmacological scientific bases of its effects. The most important active principle, Delta-9-tetrahydrocannabinol, was identified in the second half of the last century, and subsequently two receptors were identified and cloned: CB1 that is primarily present in the central nervous system, and CB2 that is present on the cells of the immune system. Endogenous ligands, called endocannabinoids, were characterized. The anandamide was the first one to be discovered. The effectiveness of the cannabinoids in the treatment of nausea and vomit due to anti-neoplastic chemotherapy and in the wasting-syndrome during AIDS is recognized. Moreover, the cannabinoids are analgesic, and their activity is comparable to the weak opioids. Furthermore, parallels exist between opioid and cannabinoid receptors, and evidence is accumulating that the two systems sometimes may operate synergistically. The interest of the pharmaceutical companies led to the production of various drugs, whether synthetic or natural derived. The good ratio between the polyunsatured fatty acids omega-3 and omega-6 of the oil of Cannabis seeds led to reduction of the phlogosis and an improvement of the pain symptoms in patients with chronic musculo-skeletal inflammation.”

http://www.ncbi.nlm.nih.gov/pubmed/19388223

An analgesic role for cannabinoids.

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Abstract

“Cannabinoids have significant analgesic properties in animal models, particularly for chronic pain states, but there are few human studies. An endogenous cannabinoid system, with specific receptors and transmitters, has recently been discovered. This discovery has led pharmacologists to explore the potential of synthetic cannabinoids to selectively target chronic pain disorders without producing the side effects associated with cannabis. Well-controlled clinical trials on cannabinoids, and cannabinoid delivery systems, are now required.”

http://www.ncbi.nlm.nih.gov/pubmed/11130354

Cannabinoid mechanisms of pain suppression.

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Abstract

“A large body of literature indicates that cannabinoids suppress behavioral responses to acute and persistent noxious stimulation in animals. This review examines neuroanatomical, behavioral, and neurophysiological evidence supporting a role for cannabinoids in suppressing pain at spinal, supraspinal, and peripheral levels. Localization studies employing receptor binding and quantitative autoradiography, immunocytochemistry, and in situ hybridization are reviewed to examine the distribution of cannabinoid receptors at these levels and provide a neuroanatomical framework with which to understand the roles of endogenous cannabinoids in sensory processing. Pharmacological and transgenic approaches that have been used to study cannabinoid antinociceptive mechanisms are described. These studies provide insight into the functional roles of cannabinoid CB1 (CB1R) and CB2 (CB2R) receptor subtypes in cannabinoid antinociceptive mechanisms, as revealed in animal models of acute and persistent pain. The role of endocannabinoids and related fatty acid amides that are implicated in endogenous mechanisms for pain suppression are discussed. Human studies evaluating therapeutic potential of cannabinoid pharmacotherapies in experimental and clinical pain syndromes are evaluated. The potential of exploiting cannabinoid antinociceptive mechanisms in novel pharmacotherapies for pain is discussed.”

http://www.ncbi.nlm.nih.gov/pubmed/16596786

Recent data on cannabinoids and their pharmacological implications in neuropathic pain.

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Abstract

“Natural cannabinoids have been used for centuries for their psychotropic properties, but their possible therapeutic implications in analgesia have been recently documented. The present review intended to make an analysis of the neuroanatomy and physiology of the cannabinoid system (receptors, functions, agents acting on these receptors) and of its implications in neuropathic pain. There were also described the complex phenomena implicated in the generation and maintenance of neuropathic pain, by high lightening the implications of endogenous cannabinoids in this complex of painful conditions. The pharmacological analgesia test proves of cannabinoid implication in neuropathic pain was sustained by many studies presented in this paper. Therapeutic approaches using natural and synthetic cannabinoid receptor agonists were reviewed. Therapeutic perspectives in neuropathic pain might involve the development of new agents that influence the cannabinoid system. Thus, peripheral acting cannabinoid 1 receptors agonists, selective cannabinoid 2 receptor agonists and also modulators of endocannabinoids metabolism might be a way to success in the treatment of this complex entity called neuropathic pain.”

http://www.ncbi.nlm.nih.gov/pubmed/20108515

Smoking Marijuana Eases Chronic Neuropathic Pain.

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“Smoking cannabis reduces chronic neuropathic pain and also improves sleep, according to new research published today in the Canadian Medical Association Journal.

A single inhalation of 25 mg of 9.4% tetrahydrocannabinol herbal cannabis 3 times a day for 5 days was sufficient to achieve these outcomes, lead study author Mark A. Ware, MBBS, from McGill University Health Center, Montreal, Canada, told Medscape Medical News in an interview.

“Patients have been reporting that cannabis helps control their pain, and they have been saying so for a long time,” Dr. Ware said. “At the time that we had secured the funding and began the trial, there had been no clinical trials that had established this or investigated it.”

In addition, a large body of scientific knowledge is emerging abound the role of cannabinoid receptors and cannabinoid ligands in the human body, providing a potential scientific explanation as to why cannabinoids would be analgesic, he added. “So the 2 main supports came together, and in Canada at the time, there was an environment where we were able to secure funding sufficient for studies of this.”

Posttraumatic and Postsurgical Neuropathy

The study included 21 individuals older than 18 years (mean age, 45.4 years) with posttraumatic or postsurgical neuropathic pain lasting for at least 3 months. They were randomly assigned to receive cannabis at 4 potencies — 0%, 2.5%, 6%, and 9.4% tetrahydrocannabinol — during 4 periods in a crossover design. Each period lasted 14 days and began with 5 days of cannabis use followed by a 9-day washout period.

The cannabis doses were delivered in a single smoked inhalation using a titanium pipe. Patients self-administered the first dose of each period under supervision and were instructed to inhale for 5 seconds while the cannabis was lit, hold the smoke in their lungs for 10 seconds, and then exhale. They self-administered the remaining doses for each period at home.

The participants were allowed to continue their routine medications, and the use of acetaminophen as breakthrough analgesia was also permitted.

Pain intensity was measured using an 11-item numeric rating scale that used “no pain” and “worst pain possible” as anchors.

The study found that the higher dose of cannabis was the most efficient in reducing pain. The average daily pain intensity was 5.4 with the 9.4% tetrahydrocannabinol cannabis dose compared with 6.1 with the 0% or placebo dose (95% confidence interval, 0.02 – 1.4; P = .023).

In addition, participants reported significantly more drowsiness and reported getting to sleep more easily, faster, and with fewer periods of wakefulness when taking the 9.4% dose than when taking the 0% dose ( P < .05). The higher dose also improved anxiety and depression compared with the placebo dose.

Blind Held; Studies Feasible

“It was feared that participants would know right away if they were smoking cannabis because of the acute psychoactive effects of the drug, but our results do not support this,” Dr. Ware noted. “They do show that short-term placebo-controlled trials of smoked cannabis are feasible.”

He would like his study to act as a stimulus for other studies on cannabis and pain relief.

“Studies of this kind can be done. Ours was difficult to do because it was the first time we had done anything like this. We were breaking new ground with regard to regulations and so on, but it is possible. Having done it once, it’s not as difficult to do it again. So our results raise the possibility of extending the study for a longer duration, or being able to look at safety issues, and so on. It is possible to do a scientific trial with this compound. Your political views shouldn’t matter. This is just good science,” Dr. Ware said.

In a related commentary, Henry J. McQuay, DM, from Balliol College, Oxford, United Kingdom, writes that the study authors should be congratulated for tackling the question of whether cannabis helps in neuropathic pain, “particularly given that the regulatory hurdles for their trial must have been a nightmare.”

He concludes that the study “adds to the trickle of evidence that cannabis may help some of the patients who are struggling at present.””

http://www.medscape.com/viewarticle/727702

Cannabis spray found to help relieve cancer pain

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“Cancer patients who used a cannabis mouthspray had their level of pain reduced by 30%, a study has shown.

The cannabis-based spray, like a mouth freshener, was used on 177 patients by researchers from Edinburgh University.

They found it reduced pain levels by 30% in a group of cancer patients, all in the Edinburgh area, who had not been helped by morphine or other medicines.

The spray was developed so that it did not affect the mental state of patients in the way that using cannabis would.

Site of pain

They said the spray worked by activating molecules in the body called cannabinoid receptors which can stop nerve signals being sent to the brain from the site of pain.

Professor Marie Fallon, of the Edinburgh Cancer Research Centre at Edinburgh University, said: “These early results are very promising and demonstrate that cannabis-based medicines may deliver effective treatment for people with severe pain.

“Prescription of these drugs can be very useful in combating debilitating pain, but it is important to understand the difference between their medical and recreational use.””

http://www.plymouthwired.co.uk/news.php/2777-Cannabis-spray-found-to-help-relieve-cancer-pain

The Endocannabinoid System and Pain

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“Cannabis has been used for more than twelve thousand years and for many different purposes (i.e. fiber, medicinal, recreational). However, the endocannabinoid signaling system has only recently been the focus of medical research and considered a potential therapeutic target. Endocannabinoids … Continue reading → Continue reading →