Tag Archives: antagonists

Rimonabant, a selective cannabinoid1 receptor antagonist, protects against light-induced retinal degeneration in vitro and in vivo.

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“The endocannabinoid system is involved in some neurodegenerative diseases such as Alzheimer’s disease. An endogenous constellation of proteins related to cannabinoid1 receptor signaling, including free fatty acids, diacylglycerol lipase, and N-acylethanolamine-hydrolyzing acid amidase, are localized in the murine retina. Moreover, the expression levels of endogenous agonists of cannabinoid receptors are changed in the vitreous fluid.

However, the role of the endocannabinoid system in the retina, particularly in the light-induced photoreceptor degeneration, remains unknown. Therefore, we investigated involvement of the cannabinoid1 receptor in light-induced retinal degeneration using in vitro and in vivo models.

Rimonabant suppressed light-induced photoreceptor cell death. Cannabinoid1 receptor expression was upregulated by light exposure. Treatment with rimonabant improved both a- and b-wave amplitudes and the thickness of the outer nuclear layer.

These results suggest that the cannabinoid1 receptor is involved in light-induced retinal degeneration and it may represent a therapeutic target in the light-induced photoreceptor degeneration related diseases.”

https://www.ncbi.nlm.nih.gov/pubmed/28315677

The role of exercise training and the endocannabinoid system in atherosclerotic plaque burden and composition in Apo-E-deficient mice.

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“We investigated the effect of combining exercise training and treatment with an endocannabinoid receptor 1 inhibitor (Rimonabant) on atherosclerosis burden and composition.

Both exercise and rimonabant treatments induced plaque regression and promoted plaque stability. The combined treatment failed to show additive or synergistic benefits relative to either intervention alone.”

https://www.ncbi.nlm.nih.gov/pubmed/28254386

MECHANISMS IN ENDOCRINOLOGY: Endocannabinoids and metabolism: past, present and future.

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“The endocannabinoid system (ECS), including cannabinoid type 1 and type 2 receptors (CB1R and CB2R), endogenous ligands called endocannabinoids and their related enzymatic machinery, is known to have a role in the regulation of energy balance.

Past information generated on the ECS, mainly focused on the involvement of this system in the central nervous system regulation of food intake, while at the same time clinical studies pointed out the therapeutic efficacy of brain-penetrant CB1R antagonists like rimonabant for obesity and metabolic disorders.

Rimonabant was removed from the market in 2009 and its obituary written due to its psychiatric side effects. However, in the meanwhile a number of investigations had started to highlight the roles of the peripheral ECS in the regulation of metabolism, bringing up new hope that the ECS might still represent target for treatment.

Accordingly, peripherally-restricted CB1R antagonists or inverse agonists have shown to effectively reduce body weight, adiposity, insulin resistance and dyslipidemia in obese animal models.

Very recent investigations have further expanded the possible toolbox for the modulation of the ECS, by demonstrating the existence of endogenous allosteric inhibitors of CB1R, the characterization of the structure of the human CB1R, and the likely involvement of CB2R in metabolic disorders. Here we give an overview of these findings, discussing what the future may hold in the context of strategies targeting the ECS in metabolic disease.”

https://www.ncbi.nlm.nih.gov/pubmed/28246151

Current Drug Targets in Obesity Pharmacotherapy – A Review.

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“Obesity, an impending global pandemic, is not being effectively controlled by current measures such as lifestyle modifications, bariatric surgery or available medications. Its toll on health and economy compels us to look for more effective measures. Fortunately, the advances in biology and molecular technology have been in our favour for delineating new pathways in the pathophysiology of obesity and have led to subsequent development of new drug targets. Development of anti-obesity drugs has often been riddled with problems in the past. Some of the recently approved drugs for pharmacotherapy of obesity have been lorcaserin, phentermine/topiramate and naltrexone/bupropion combinations.

Several promising new targets are currently being evaluated, such as amylin analogues (pramlintide, davalintide), leptin analogues (metreleptin), GLP-1 analogues (exenatide, liraglutide, TTP-054), MC4R agonists (RM-493), oxyntomodulin analogues, neuropeptide Y antagonists (velneperit), cannabinoid type-1 receptor blockers (AM-6545), MetAP2 inhibitors (beloranib), lipase inhibitors (cetilistat) and anti-obesity vaccines (ghrelin, somatostatin, Ad36).

Many of these groups of drugs act as “satiety signals” while others act by antagonizing orexigenic signals, increasing fat utilisation and decreasing absorption of fats. Since these targets act through various pathways, the possibility of combined use of two or more classes of these drugs unlocks numerous therapeutic avenues. Hence, the dream of personalized management of obesity might be growing closer to reality.”

https://www.ncbi.nlm.nih.gov/pubmed/28245771

The cannabinoid 1 receptor antagonist, AM251, prolongs the survival of rats with severe acute pancreatitis.

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“It has recently been recognized that anandamide (arachidonylethanolamide), which is an endogeneous-cannabinoid (endocannabinoid), mediates septic shock.

Cannabinoid means a mind-active material in cannabis (marijuana).

Anandamide is mainly produced by macrophages. Cannabinoid 1 (CB1) receptor, which is one of the cannabiniod receptors, is also known to mediate hypotensive shock.

The role of endocannabinoids in the progression of acute pancreatitis is unclear. The aims of this study are to clarify their relationship and to find a new therapeutic strategy by regulating the endocannabinoid signaling in acute pancreatitis.

This is the first report to show that endocannabinoids are involved in the deterioration of acute pancreatitis and that the down-regulation of endocannabinoid signaling may be a new therapeutic strategy for severe acute pancreatitis.”

https://www.ncbi.nlm.nih.gov/pubmed/16141678

Cannabinoid receptor-1 blockade attenuates acute pancreatitis in obesity by an adiponectin mediated mechanism.

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“Obesity is a risk factor for increased severity of acute pancreatitis.

Adipocytes produce adiponectin, an anti-inflammatory molecule that is paradoxically decreased in the setting of obesity. We have shown that adiponectin concentration inversely mirrors the severity of pancreatitis in obese mice.

Cannabinoid receptor CB-1 blockade increases circulating adiponectin concentration. We, therefore, hypothesize that blockade of CB-1 would increase adiponectin and attenuate pancreatitis severity.

Rimonabant treatment significantly increased circulating adiponectin concentration in obese mice.

In obese mice, cannabinoid receptor CB-1 blockade with rimonabant attenuates the severity of acute pancreatitis by an adiponectin-mediated mechanism.”

https://www.ncbi.nlm.nih.gov/pubmed/19225848

Activation of cannabinoid receptor 2 reduces inflammation in acute experimental pancreatitis via intra-acinar activation of p38 and MK2-dependent mechanisms.

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“The endocannabinoid system has been shown to mediate beneficial effects on gastrointestinal inflammation via cannabinoid receptors 1 (CB(1)) and 2 (CB(2)).

These receptors have also been reported to activate the MAP kinases p38 and c-Jun NH(2)-terminal kinase (JNK), which are involved in early acinar events leading to acute pancreatitis and induction of proinflammatory cytokines.

Our aim was to examine the role of cannabinoid receptor activation in an experimental model of acute pancreatitis and the potential involvement of MAP kinases.

The unselective CB(1)/CB(2) agonist HU210 ameliorated pancreatitis in wild-type and CB(1)-/- mice, indicating that this effect is mediated by CB(2).

Furthermore, blockade of CB(2), not CB(1), with selective antagonists engraved pathology.

Stimulation with a selective CB(2) agonist attenuated acute pancreatitis and an increased activation of p38 was observed in the acini.

With use of MK2-/- mice, it could be demonstrated that this attenuation is dependent on MK2. Hence, using the MK2-/- mouse model we reveal a novel CB(2)-activated and MAP kinase-dependent pathway that modulates cytokine expression and reduces pancreatic injury and affiliated complications.”

https://www.ncbi.nlm.nih.gov/pubmed/23139224

Pregnenolone blocks cannabinoid-induced acute psychotic-like states in mice.

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“Cannabis-induced acute psychotic-like states (CIAPS) represent a growing health issue, but their underlying neurobiological mechanisms are poorly understood.

The use of antipsychotics and benzodiazepines against CIAPS is limited by side effects and/or by their ability to tackle only certain aspects of psychosis. Thus, safer wide-spectrum treatments are currently needed.

Although the blockade of cannabinoid type-1 receptor (CB1) had been suggested as a therapeutical means against CIAPS, the use of orthosteric CB1 receptor full antagonists is strongly limited by undesired side effects and low efficacy.

The neurosteroid pregnenolone has been recently shown to act as a potent endogenous allosteric signal-specific inhibitor of CB1 receptors. Thus, we tested in mice the potential therapeutic use of pregnenolone against acute psychotic-like effects of Δ9-tetrahydrocannabinol (THC), the main psychoactive component of cannabis.

We found that pregnenolone blocks a wide spectrum of THC-induced endophenotypes typically associated with psychotic-like states, including impairments in cognitive functions, somatosensory gating and social interaction. Overall, this work reveals that signal-specific inhibitors mimicking pregnenolone effects can be considered as promising new therapeutic tools to treat CIAPS.”  https://www.ncbi.nlm.nih.gov/pubmed/28220044

“Pregnenolone can protect the brain from cannabis intoxication. The administration of the main active principle of Cannabis sativa (marijuana), Δ(9)-tetrahydrocannabinol (THC), substantially increases the synthesis of pregnenolone in the brain via activation of the type-1 cannabinoid (CB1) receptor. Pregnenolone then, acting as a signaling-specific inhibitor of the CB1 receptor, reduces several effects of THC. This negative feedback mediated by pregnenolone reveals a previously unknown paracrine/autocrine loop protecting the brain from CB1 receptor overactivation that could open an unforeseen approach for the treatment of cannabis intoxication and addiction.”  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4057431/

Involvement of Cannabinoid Signaling in Vincristine-Induced Gastrointestinal Dysmotility in the Rat.

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“In different models of paralytic ileus, cannabinoid receptors are overexpressed and endogenous cannabinoids are massively released, contributing to gastrointestinal dysmotility. The antitumoral drug vincristine depresses gastrointestinal motility and a similar mechanism could participate in this effect. Therefore, our aim was to determine, using CB1 and CB2 antagonists, whether an increased endocannabinoid tone is involved in vincristine-induced gastrointestinal ileus.

Key results: Vincristine induced damage to the mucosa of ileum and colon and reduced gastrointestinal motor function at 0.5 mg/kg. The effect on motor function was particularly evident when the study started 24 h after administration. AM251, but not AM630, significantly prevented vincristine effect, particularly in the small intestine, when administered thrice. AM251 alone did not significantly alter gastrointestinal motility.

Conclusions: The fact that AM251, but not AM630, is capable of reducing the effect of vincristine suggests that, like in other experimental models of paralytic ileus, an increased cannabinoid tone develops and is at least partially responsible for the alterations induced by the antitumoral drug on gastrointestinal motor function. Thus, CB1 antagonists might be useful to prevent/treat ileus induced by vincristine.”  https://www.ncbi.nlm.nih.gov/pubmed/28220074

“Paralytic ileus: Obstruction of the intestine due to paralysis of the intestinal muscles.”  http://www.medicinenet.com/script/main/art.asp?articlekey=7886

Implication of cannabinoids in neurological diseases.

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“1. Preparations from Cannabis sativa (marijuana) have been used for many centuries both medicinally and recreationally. 2. Recent advances in the knowledge of its pharmacological and chemical properties in the organism, mainly due to Delta(9)-tetrahydrocannabinol, and the physiological roles played by the endocannabinoids have opened up new strategies in the treatment of neurological and psychiatric diseases. 3. Potential therapeutic uses of cannabinoid receptor agonists include the management of spasticity and tremor in multiple sclerosis/spinal cord injury, pain, inflammatory disorders, glaucoma, bronchial asthma, cancer, and vasodilation that accompanies advanced cirrhosis. CB(1) receptor antagonists have therapeutic potential in Parkinson’s disease. 4. Dr. Julius Axelrod also contributed in studies on the neuroprotective actions of cannabinoids.” https://www.ncbi.nlm.nih.gov/pubmed/16699878

“Medical marijuana: emerging applications for the management of neurologic disorders.” https://www.ncbi.nlm.nih.gov/pubmed/15458761