Tag Archives: antagonists

Targeting the endocannabinoid/CB1 receptor system for treating obesity in Prader–Willi syndrome

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“Extreme obesity is a core phenotypic feature of Prader–Willi syndrome (PWS). Among numerous metabolic regulators, the endocannabinoid (eCB) system is critically involved in controlling feeding, body weight, and energy metabolism, and a globally acting cannabinoid-1 receptor (CB1R) blockade reverses obesity both in animals and humans.

We studied eCB ‘tone’ in individuals with PWS and in the Magel2-null mouse model that recapitulates the major metabolic phenotypes of PWS and determined the efficacy of a peripherally restricted CB1R antagonist, JD5037 in treating obesity in these mice.

 Dysregulation of the eCB/CB1R system may contribute to hyperphagia and obesity in Magel2-null mice and in individuals with PWS. Our results demonstrate that treatment with peripherally restricted CB1R antagonists may be an effective strategy for the management of severe obesity in PWS.

In conclusion, the current study provides the first evidence that the eCB system may contribute to severe obesity both in PWS children and adults and in an established mouse model for this syndrome. Our results confirm that the eCB system contributes to the metabolic phenotype associated with PWS. Moreover, specifically targeting the peripheral eCB system in obese Magel2-null mice was found to be as efficacious as in DIO animals, and, therefore, it may represent a novel approach to treating obesity and its complications in PWS. This would also provide the rationale for the development and clinical testing of peripherally restricted CB1R antagonists for treating obesity in PWS.”  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5123200/

“Cannabinoid-1 receptor (CB1R) blockers as medicines: beyond obesity and cardiometabolic disorders to substance abuse/drug addiction with CB1R neutral antagonists.” https://www.ncbi.nlm.nih.gov/pubmed/22335400

“The phytocannabinoid, Delta(9)-tetrahydrocannabivarin (THCV), can block cannabinoid CB(1) receptors” http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2931567/

Transient Cannabinoid Receptor 2 Blockade during Immunization Heightens Intensity and Breadth of Antigen-specific Antibody Responses in Young and Aged mice.

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“The hallmark of vaccines is their ability to prevent the spread of infectious pathogens and thereby serve as invaluable public health tool. Despite their medical relevance, there is a gap in our understanding of the physiological factors that mediate innate and adaptive immune response to vaccines.

The endocannabinoid (eCB) system is a critical modulator of homeostasis in vertebrates. Our results indicate that macrophages and dendritic cells produce the endocannabinoid, 2-arachidonoyl-sn-glycerol (2-AG) upon antigen activation.

We have also established that 2-AG levels are upregulated in the serum and in the lymph node of mice during vaccination.

We hypothesized that the intrinsic release of eCBs from immune cells during activation by pathogenic antigens mitigate inflammation, but also suppress overall innate and adaptive immune response.

Here we demonstrate, for the first time, that transient administration of the cannabinoid receptor 2 antagonist AM630 (10 mg/kg) or inverse agonist JTE907 (3 mg/kg) during immunization heightens the intensity and breadth of antigen-specific immune responses in young and aged mice through the upregulation of immunomodulatory genes in secondary lymphoid tissues.”

 https://www.ncbi.nlm.nih.gov/pubmed/28209996

AM251 Suppresses Epithelial-Mesenchymal Transition of Renal Tubular Epithelial Cells.

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“Epithelial-mesenchymal transition (EMT) of renal tubular epithelial cells is one of the causative mechanisms of kidney fibrosis.

In our study, we screened lipophilic compounds using a lipid library including approximately 200 lipids to identify those that suppressed EMT induced by a transforming growth factor (TGF)-β1 stimulus.

Our findings regarding the effects of AM251 on the TGF-β signaling pathway may inform development of a novel therapeutic agent suppressing EMT, thus preventing kidney fibrosis.”

https://www.ncbi.nlm.nih.gov/pubmed/27936102

Two Janus cannabinoids that are both CB2 agonists and CB1 antagonists.

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“The cannabinoid signaling system includes two G protein coupled receptors, CB1 and CB2. These receptors are widely distributed throughout the body and have each been implicated in many physiologically important processes.

Though the cannabinoid signaling system has therapeutic potential, a persistent hurdle has remained the development of receptor-selective ligands. Because CB1 and CB2 are involved in diverse processes, it would be advantageous develop ligands that differentially engaging CB1 and CB2.

In summary we have determined that GW405833 and AM1710 are not only CB2 agonists but also CB1 antagonists, with distinctive and complex signaling properties. Thus experiments using these compounds must take into account their potential activity at CB1 receptors.”

https://www.ncbi.nlm.nih.gov/pubmed/27927913

Targeting the endocannabinoid/CB1 receptor system for treating obesity in Prader-Willi syndrome.

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“Extreme obesity is a core phenotypic feature of Prader-Willi syndrome (PWS).

Among numerous metabolic regulators, the endocannabinoid (eCB) system is critically involved in controlling feeding, body weight, and energy metabolism, and a globally acting cannabinoid-1 receptor (CB1R) blockade reverses obesity both in animals and humans.

The first-in-class CB1R antagonist rimonabant proved effective in inducing weight loss in adults with PWS. However, it is no longer available for clinical use because of its centrally mediated, neuropsychiatric, adverse effects.

CONCLUSIONS:

Dysregulation of the eCB/CB1R system may contribute to hyperphagia and obesity in Magel2-null mice and in individuals with PWS. Our results demonstrate that treatment with peripherally restricted CB1R antagonists may be an effective strategy for the management of severe obesity in PWS.”

https://www.ncbi.nlm.nih.gov/pubmed/27900261

Cannabinoid receptors and TRPA1 on neuroprotection in a model of retinal ischemia.

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“Retinal ischemia is a pathological event present in several retinopathies such as diabetic retinopathy and glaucoma, leading to partial or full blindness with no effective treatment available.

Since synthetic and endogenous cannabinoids have been studied as modulators of ischemic events in the central nervous system (CNS), the present study aimed to investigate the involvement of cannabinoid system in the cell death induced by ischemia in an avascular (chick) retina.

We observed that chick retinal treatment with a combination of WIN 55212-2 and cannabinoid receptor antagonists (either AM251/O-2050 or AM630) decreased the release of lactate dehydrogenase (LDH) induced by retinal ischemia in an oxygen and glucose deprivation (OGD) model.

Further, the increased availability of endocannabinoids together with cannabinoid receptor antagonists also had a neuroprotective effect.

Surprisingly, retinal exposure to any of these drugs alone did not prevent the release of LDH stimulated by OGD.

Since cannabinoids may also activate transient receptor potential (TRP) channels, we investigated the involvement of TRPA1 receptors (TRPA1) in retinal cell death induced by ischemic events.

We demonstrated the presence of TRPA1 in the chick retina, and observed an increase in TRPA1 content after OGD, both by western blot and immunohistochemistry.

In addition, the selective activation of TRPA1 by mustard oil (MO) did not worsen retinal LDH release induced by OGD, whereas the blockage of TRPA1 completely prevented the extravasation of cellular LDH in ischemic condition.

Hence, these results show that during the ischemic event there is an augment of TRPA1, and activation of this receptor is important in cell death induction.

The data also indicate that metabotropic cannabinoid receptors, both type 1 and 2, are not involved with the cell death found in the early stages of ischemia. Therefore, the study points to a potential role of TRPA1 as a target for neuroprotective approaches in retinal ischemia.”

https://www.ncbi.nlm.nih.gov/pubmed/27876485

Allosteric Modulation: An Alternate Approach Targeting the Cannabinoid CB1 Receptor.

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“The cannabinoid CB1 receptor is a G protein coupled receptor and plays an important role in many biological processes and physiological functions.

A variety of CB1 receptor agonists and antagonists, including endocannabinoids, phytocannabinoids, and synthetic cannabinoids, have been discovered or developed over the past 20 years.

In 2005, it was discovered that the CB1 receptor contains allosteric site(s) that can be recognized by small molecules or allosteric modulators.

A number of CB1 receptor allosteric modulators, both positive and negative, have since been reported and importantly, they display pharmacological characteristics that are distinct from those of orthosteric agonists and antagonists.

Given the psychoactive effects commonly associated with CB1 receptor agonists and antagonists/inverse agonists, allosteric modulation may offer an alternate approach to attain potential therapeutic benefits while avoiding inherent side effects of orthosteric ligands.

This review details the complex pharmacological profiles of these allosteric modulators, their structure-activity relationships, and efforts in elucidating binding modes and mechanisms of actions of reported CB1 allosteric modulators.

The ultimate development of CB1 receptor allosteric ligands could potentially lead to improved therapies for CB1-mediated neurological disorders.”

https://www.ncbi.nlm.nih.gov/pubmed/27879006

Antagonism of cannabinoid receptor 1 attenuates the anti-inflammatory effects of electroacupuncture in a rodent model of migraine.

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“The anti-nociceptive effects of electroacupuncture (EA) in migraine have been documented in multiple randomised controlled trials.

Neurogenic inflammation plays a key role in migraine attacks, and the anti-inflammatory effects of acupuncture have been associated with the type 1 cannabinoid (CB1) receptor.

CB1 receptors appear to mediate anti-inflammatory effects of EA in a rat model of migraine.”

https://www.ncbi.nlm.nih.gov/pubmed/27834685

The cannabinoid receptor CB1 contributes to the development of ectopic lesions in a mouse model of endometriosis.

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“Does signaling via the cannabinoid (CB1) receptor play a role in the pathogenesis of endometriosis in a mouse model?

The expression of components of the endocannabinoid system has been demonstrated in both mouse and human uteri. CB1 receptors are expressed in human epithelial and stromal cell lines derived from eutopic endometrium and deep infiltrating endometriosis nodules.

This was a randomized study in a mouse model of endometriosis.

We provide evidence that endocannabinoid signaling via CB1 receptor plays a role in the development of endometriosis in a mouse model.

However, the relative contribution of the CB1-mediated signaling pathways active in inflammatory, uterine and peritoneal cells remains to be ascertained. Since the study was performed in a mouse model, the significance of the findings in the human system warrants further investigation.

Clarifying the function and regulation of CB1 and its molecular interactions with endogenous ligands, and how endocannabinoids levels are regulated in women with endometriosis, represent critical areas of research for the potential development of a novel medical treatment of the disease.”

https://www.ncbi.nlm.nih.gov/pubmed/27821707

Endogenous cannabinoid system alterations and their role in epileptogenesis after brain injury in rat.

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“Post-traumatic epilepsy (PTE) is one of the most common complications resulting from brain injury, however, antiepileptic drugs usually fail to prevent it.

Several lines of evidence have demonstrated that the endogenous cannabinoid system (ECS) plays a pivotal role during epileptogenesis in several animal models.

A recent study has shown that a cannabinoid type 1 (CB1) receptor antagonist could suppress long-term neuron hyperexcitability after brain injury, but the underlying mechanisms remain largely unknown.

In this study, we first analyzed the dynamic expression of different components of the ECS at various time points after brain injury in rats. Then, we conducted a 12-month-long session of behavioral monitoring after the brain injury, and based on the results, the rats were divided into a PTE group and a non-PTE group. Finally, the changes in the ECS between the two groups were compared.

We found that the ECS exhibited a biphasic alteration after brain injury; the expression of the CB1 receptor and 2-arachidonoylglycerol (2-AG) in the PTE group was significantly higher than that of the non-PTE group 12 months after traumatic brain injury.

Our preliminary results indicated that the ECS might be involved in post-traumatic epileptogenesis.”

https://www.ncbi.nlm.nih.gov/pubmed/27810514