Tag Archives: antagonists

Cannabinoid type 1 receptor antagonism ameliorates harmaline-induced essential tremor in rat.

Posted on by
Reply

“Essential tremor (ET) is a neurological disorder with unknown etiology. Its symptoms include cerebellar motor disturbances, cognitive and personality changes, hearing and olfactory deficits. Excitotoxic cerebellar climbing fibre hyperactivity may underlie essential tremor and has been emulated in rodents by systemic harmaline administration.

Cannabinoid receptor agonists can cause motor disturbances although there are also anecdotal reports of therapeutic benefits of cannabis in motor disorders. We set out to establish the effects of cannabinoid type 1 receptor agonism and antagonism in an established rodent model of ET using a battery of accepted behaviour assays in order to determine risk and therapeutic potential of endocannabinoid system modulation in ET.

Overall, harmaline induced robust tremor that was typically worsened across the measured behavioural domains by CB type 1 (CB1 ) receptor agonism but ameliorated by cannabinoid type 1 receptor antagonism.

CONCLUSIONS AND IMPLICATIONS:

These results provide the first evidence of effects of endocannabinoid system modulation on motor function in the harmaline model of essential tremor and suggest that CB1 receptor manipulation warrants clinical investigation as a therapeutic approach to protection against behavioural disturbances associated with essential tremor.”

http://www.ncbi.nlm.nih.gov/pubmed/27545646

Peripheral and central CB1 cannabinoid receptors control stress-induced impairment of memory consolidation.

Posted on by
Reply

“Stressful events can generate emotional memories linked to the traumatic incident, but they also can impair the formation of nonemotional memories. Although the impact of stress on emotional memories is well studied, much less is known about the influence of the emotional state on the formation of nonemotional memories.

We used the novel object-recognition task as a model of nonemotional memory in mice to investigate the underlying mechanism of the deleterious effect of stress on memory consolidation.

Systemic, hippocampal, and peripheral blockade of cannabinoid type-1 (CB1) receptors abolished the stress-induced memory impairment. Genetic deletion and rescue of CB1 receptors in specific cell types revealed that the CB1 receptor population specifically in dopamine β-hydroxylase (DBH)-expressing cells is both necessary and sufficient for stress-induced impairment of memory consolidation, but CB1 receptors present in other neuronal populations are not involved.

Strikingly, pharmacological manipulations in mice expressing CB1 receptors exclusively in DBH+ cells revealed that both hippocampal and peripheral receptors mediate the impact of stress on memory consolidation.

Thus, CB1 receptors on adrenergic and noradrenergic cells provide previously unrecognized cross-talk between central and peripheral mechanisms in the stress-dependent regulation of nonemotional memory consolidation, suggesting new potential avenues for the treatment of cognitive aspects on stress-related disorders.”

http://www.ncbi.nlm.nih.gov/pubmed/27528659

Hybrid inhibitor of peripheral cannabinoid-1 receptors and inducible nitric oxide synthase mitigates liver fibrosis.

Posted on by
Reply

“Liver fibrosis, a consequence of chronic liver injury and a way station to cirrhosis and hepatocellular carcinoma, lacks effective treatment.

Endocannabinoids acting via cannabinoid-1 receptors (CB1R) induce profibrotic gene expression and promote pathologies that predispose to liver fibrosis.

CB1R antagonists produce opposite effects, but their therapeutic development was halted due to neuropsychiatric side effects. Inducible nitric oxide synthase (iNOS) also promotes liver fibrosis and its underlying pathologies, but iNOS inhibitors tested to date showed limited therapeutic efficacy in inflammatory diseases.

Here, we introduce a peripherally restricted, orally bioavailable CB1R antagonist, which accumulates in liver to release an iNOS inhibitory leaving group.

Additionally, it was able to slow fibrosis progression and to attenuate established fibrosis. Thus, dual-target peripheral CB1R/iNOS antagonists have therapeutic potential in liver fibrosis.

For multifactorial chronic diseases, such as fibrosis, the conventional pharmacological approach based on the “one-disease/one-target/one-drug” paradigm limits therapeutic efficacy and could be improved by simultaneously hitting multiple therapeutic targets.

One such target is the endocannabinoid/cannabinoid-1 receptor (endocannabinoid/CB1R) system.

The dual targeting of peripheral CB1R and iNOS demonstrated here exemplifies the therapeutic gain obtained by simultaneously hitting more than one molecule, which could then engage distinct as well as convergent cellular pathways. The advantage of such an approach is highlighted by emerging experience with recently developed antifibrotic medications, which indicates that targeting a single pathway has limited effect on fibrotic diseases .

Thus, the approach illustrated by the present study has promise as an effective antifibrotic strategy.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4979564/

The inhibitory effect of combination treatment with leptin and cannabinoid CB1 receptor agonist on food intake and body weight gain is mediated by serotonin 1B and 2C receptors.

Posted on by
Reply

“Previous studies reported that the co-injection of leptin and cannabinoid CB1 receptor antagonists reduces food intake and body weight in rats, and this effect is more profound than that induced by these compounds individually. Additionally, serotonin mediates the effects of numerous anorectic drugs.

To investigate whether serotonin interacts with leptin and endocannabinoids to affect food intake and body weight, we administered 5-hydroxytryptamine(HT)1B and 5-hydroxytryptamine(HT)2C serotonin receptor antagonists (3 mg/kg GR 127935 and 0.5 mg/kg SB 242084, respectively) to male Wistar rats treated simultaneously with leptin (100 μg/kg) and the CB1 receptor inverse agonist AM 251 (1 mg/kg) for 3 days.

In accordance with previous findings, the co-injection of leptin and AM 251, but not the individual injection of each drug, resulted in a significant decrease in food intake and body weight gain. Blockade of the 5-HT1B and 5-HT2C receptors completely abolished the leptin- and AM 251-induced anorectic and body-weight-reducing effects.

These results suggest that serotonin mediates the leptin- and AM 251-dependent regulation of feeding behavior in rats via the 5-HT1B and 5-HT2C receptors.”

http://www.ncbi.nlm.nih.gov/pubmed/27512006

Medical Marijuana-Opportunities and Challenges

Posted on by
Reply

“Over the recent years, public and political opinions have demonstrated increasing support for the legalization of medical marijuana.

To date, 24 states as well as the District of Columbia have legalized cannabis for medical use, 4 states have legalized the recreational use of Marijuana.

Marijuana is derived from the hemp plant Cannabis sativa. Δ-9-tetrahydrocannabinol (THC) is the major psychoactive constituent of cannabis, while cannabidiol (CBD) is the major non-psychoactive constituent. THC is a partial agonist at CB1 and CB2 receptors, while CBD at high levels is an antagonist CB1 and CB2.

CB1 is abundantly expressed in the brain, and CB2 is expressed on immune cells (expression of CB2 on neurons remains controversial). The brain also produces endogenous cannabis-like substances (endocannabinoids) that bind and activate the CB1/CB2 receptors.

There is tremendous interest in harnessing the therapeutic potential of plant-derived and synthetic cannabinoids.

This Editorial provides an overview of diseases that may be treated by cannabinoids.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4948749/

Modulation of L-α-lysophosphatidylinositol/GPR55 mitogen-activated protein kinase (MAPK) signaling by cannabinoids.

Posted on by
Reply

“This study has implications for developing new therapeutics for the treatment of cancer, pain, and metabolic disorders.

GPR55 is activated by l-α-lysophosphatidylinositol (LPI) but also by certain cannabinoids.

In this study, we investigated the GPR55 pharmacology of various cannabinoids, including analogues of the CB1 receptor antagonist Rimonabant®, CB2 receptor agonists, and Cannabis sativa constituents.

Here, we show that CB1 receptor antagonists can act both as agonists alone and as inhibitors of LPI signaling under the same assay conditions. This study clarifies the controversy surrounding the GPR55-mediated actions of SR141716A; some reports indicate the compound to be an agonist and some report antagonism. In contrast, we report that the CB2 ligand GW405833 behaves as a partial agonist of GPR55 alone and enhances LPI signaling. GPR55 has been implicated in pain transmission, and thus our results suggest that this receptor may be responsible for some of the antinociceptive actions of certain CB2 receptor ligands.

Here, we report that the little investigated cannabis constituents CBDV, CBGA, and CBGV are potent inhibitors of LPI-induced GPR55 signaling.

The phytocannabinoids Δ9-tetrahydrocannabivarin, cannabidivarin, and cannabigerovarin are also potent inhibitors of LPI.

Our findings also suggest that GPR55 may be a new pharmacological target for the following C. sativa constituents: Δ9-THCV, CBDV, CBGA, and CBGV.

These Cannabis sativa constituents may represent novel therapeutics targeting GPR55.”  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249141/

“Lysophosphatidylinositol (LPI) is a bioactive lipid generated by phospholipase A2 which is believed to play an important role in several diseases.”  http://www.ncbi.nlm.nih.gov/pubmed/22285325

 “The putative cannabinoid receptor GPR55 promotes cancer cell proliferation.  In this issue of Oncogene, two groups demonstrated that GPR55 is expressed in various cancer types in an aggressiveness-related manner, suggesting a novel cancer biomarker and a potential therapeutic target.” http://www.ncbi.nlm.nih.gov/pubmed/21057532
“The orphan G protein-coupled receptor GPR55 promotes cancer cell proliferation via ERK. These findings reveal the importance of GPR55 in human cancer, and suggest that it could constitute a new biomarker and therapeutic target in oncology.” http://www.ncbi.nlm.nih.gov/pubmed/20818416
“The putative cannabinoid receptor GPR55 defines a novel autocrine loop in cancer cell proliferation. These findings may have important implications for LPI as a novel cancer biomarker and for its receptor GPR55 as a potential therapeutic target.”  http://www.ncbi.nlm.nih.gov/pubmed/20838378
“L-α-lysophosphatidylinositol meets GPR55: a deadly relationship. Evidence points to a role of L-α-lysophosphatidylinositol (LPI) in cancer.”  http://www.ncbi.nlm.nih.gov/pubmed/21367464

Endocannabinoids: new targets for drug development.

Posted on by
Reply

“The possible therapeutic use of marijuana s active principles, the cannabinoids, is currently being debated.

It is now known that these substances exert several of their pharmacological actions by activating specific cell membrane receptors, the CB1 and CB2 cannabinoid receptor subtypes.

This knowledge led to the design of synthetic cannabinoid agonists and antagonists with high therapeutic potential.

The recent discovery of the endocannabinoids, i.e. endogenous metabolites capable of activating the cannabinoid receptors, and the understanding of the molecular mechanisms leading to their biosynthesis and inactivation, opened a new era in research on the pharmaceutical applications of cannabinoids.

Ongoing studies on the pathological and physiological conditions regulating the tissue levels of endocannabinoids, and on the pharmacological activity of these compounds and their derivatives, may provide a lead for the development of new drugs for the treatment of nervous and immune disorders, cardiovascular diseases, pain, inflammation and cancer.

These studies are reviewed in this article with special emphasis on the chemical features that determine the interaction of endocannabinoids with the proteins mediating their activity and degradation.”

http://www.ncbi.nlm.nih.gov/pubmed/10903398

Blockade of Cannabinoid CB1 receptor attenuates the acquisition of morphine-induced conditioned place preference along with a downregulation of ERK, CREB phosphorylation, and BDNF expression in the nucleus accumbens and hippocampus.

Posted on by
Reply

“Cannabinoid CB1 receptor (CB1R) is highly expressed in the mesocorticolimbic system and associated with drug craving and relapse.

Clinical trials suggest that CB1R antagonists may represent new therapies for drug addiction.

Collectively, these findings demonstrate that 1) Repeated morphine with context exposures but not merely the pharmacological effects of morphine increased CB1R expression both in the NAc and hippocampus. 2) CB1R antagonist mediated blockade of ERK-CREB-BDNF signaling activation in the NAc and hippocampus may be an important mechanism underlying the attenuation of morphine CPP.”

http://www.ncbi.nlm.nih.gov/pubmed/27461790

The CB1 Antagonist, SR141716A, Is Protective in Permanent Photothrombotic Cerebral Ischemia.

Posted on by
Reply

“Modulation of the endocannabinoid system has been shown to have a significant impact on outcomes in animal models of stroke.

We have previously reported a protective effect of the CB1 antagonist, SR141716A, in a transient reperfusion mouse model of cerebral ischemia. This protective effect was in part mediated by activation of the 5HT1A receptor.

Here we have examined its effect in a mouse model of permanent ischemia induced by photoinjury.

The CB1 antagonist was found to be protective in this model.

As was the case following transient ischemia reperfusion, SR141716A (5mg/kg) resulted in smaller infarct fractions and stroke volumes when utilized both as a pretreatment and as a post-treatment. In contrast to the effect in a transient ischemia model, the pretreatment effect did not depend on the 5HT1A receptor.

Neurological function correlated favorably to the reduction in stroke size when SR141716A was given as a pretreatment.

With the incidence of stroke predicted to rise in parallel with an ever aging population, understanding mechanisms underlying ischemia and therapeutics remains a paramount goal of research.”

http://www.ncbi.nlm.nih.gov/pubmed/27453059

Cannabinoid Receptor 1 (CNR1) Gene Variant Moderates Neural Index of Cognitive Disruption during Nicotine Withdrawal.

Posted on by
Reply

 

“Nicotine withdrawal-related disruption of cognitive control may contribute to the reinforcement of tobacco use.

Identification of gene variants that predict this withdrawal phenotype may lead to tailored pharmacotherapy for smoking cessation.

Variation on the cannabinoid receptor 1 gene (CNR1) has been related to nicotine dependence, and CNR1 antagonists may increase attention and memory functioning.

The current findings suggest potential efficacy of cannabinoid RECEPTOR antagonism as a pharmacotherapy approach for smoking cessation among individuals who exhibit greater nicotine withdrawal-related cognitive disruption.”

http://www.ncbi.nlm.nih.gov/pubmed/27453054