Identification of a Potent and Selective Cannabinoid CB1 Receptor Antagonist from Auxarthron reticulatum.
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ABSTRACT:
SUBMITTER: Elsebai MF
PROVIDER: S-EPMC4017988 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:1 The relationship of agonist efficacy to the rate of G protein-coupled receptor signaling desensitization is controversial. 2 Expressing inwardly rectifying potassium channels (GIRKs) in Xenopus oocytes, we have devised a signaling assay that clearly identifies CB1 cannabinoid receptor agonists with low intrinsic efficacy. 3 In this assay, the synthetic CB1 agonists, AM411, AM782, AM1902, AM2233 and WIN55,212-2 and the endogenous cannabinoid, 2-arachidonoyl ester, were full agonists. 4 The synthetic CB1 agonist AM356 (methanandamide), the endogenous cannabinoids, anandamide and 2-arachidonoyl ether, and the phytocannabinoid, Delta9THC, were partial agonists. 5 The rate of desensitization of CB1 was independent of agonist efficacy. WIN55,212-2, AM782, AM1902, AM2233, and 2-arachidonoyl glycerol ester all desensitized quickly, with desensitization rates varying from 14% min(-1) to 10% min(-1). AM356, AM411, anandamide, and Delta9THC all desensitized considerably slower, at a rate of 5% min(-1). 6 Despite high potency and efficacy, AM411 desensitized as slowly as anandamide and Delta9THC. 7 CB1 agonist efficacy and rate of desensitization are not necessarily related.
| S-EPMC1574962 | biostudies-other
Project description:Although the cannabinoid CB1 receptor has been implicated in atherosclerosis, its cellspecific effects in this disease are not well understood. Here, we report that male mice with myeloid-specific Cnr1 deficiency on atherogenic background developed smaller lesions and necrotic cores than controls, while only minor genotype differences were observed in females. Male Cnr1 deficient mice showed reduced arterial monocyte recruitment and macrophage proliferation with less inflammatory phenotype. The sexspecific differences in proliferation were dependent on estrogen receptor (ER)α estradiol signaling. Kinase activity profiling revealed a CB1-dependent regulation of p53 and cyclin-dependent kinases. Transcriptomic profiling further unveiled chromatin modifications, mRNA processing and mitochondrial respiration among the key processes affected by CB1 signaling, which was supported by metabolic flux assays. Chronic administration of the peripherally-restricted CB1 antagonist JD5037 inhibited plaque progression and macrophage proliferation, but only in male mice. Finally, CNR1 expression was detectable in human carotid endarterectomy plaques and inversely correlated with proliferation, oxidative metabolism and inflammatory markers, hinting to a possible implication of CB1-dependent regulation in human pathophysiology. In conclusion, impaired macrophage CB1 signaling is atheroprotective by limiting their arterial recruitment, proliferation and inflammatory reprogramming. The importance of macrophage CB1 signaling seems to be more pronounced in male mice.
2023-12-07 | GSE249503 | GEO
Project description:Metabolic syndrome (MetS) is a complex disorder that stems from the additive effects of multiple underlying causes such as obesity, insulin resistance, and chronic low-grade inflammation. The endocannabinoid system plays a central role in appetite regulation, energy balance, lipid metabolism, insulin sensitivity, and β-cell function. The type 1 cannabinoid receptor (CB1R) antagonist SR141716A (rimonabant) showed promising antiobesity effects, but its use was discontinued due to adverse psychiatric events in some users. These adverse effects are due to antagonism of CB1R in the central nervous system (CNS). As such, CNS-sparing CB1R antagonists are presently being developed for various indications. In this study, we report that a recently described compound, 3-{1-[8-(2-chlorophenyl)-9-(4-chlorophenyl)-9H-purin-6-yl]piperidin-4-yl}-1-[6-(difluoromethoxy)pyridin-3-yl]urea (RTI1092769), a pyrazole based weak inverse agonist/antagonist of CB1 with very limited brain exposure, improves MetS related complications. Treatment with RTI1092769 inhibited weight gain and improved glucose utilization in obese mice maintained on a high fat diet. Hepatic triglyceride content and steatosis significantly improved with treatment. These phenotypes were supported by improvement in several biomarkers associated with nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). These results reinforce the idea that CB1 antagonists with limited brain exposure should be pursued for MetS and other important indications.
| S-EPMC8033769 | biostudies-literature
Project description:The CB1 cannabinoid receptor is a G-protein coupled receptor highly expressed throughout the central nervous system that is a promising target for the treatment of various disorders, including anxiety, pain, and neurodegeneration. Despite the wide therapeutic potential of CB1, the development of drug candidates is hindered by adverse effects, rapid tolerance development, and abuse potential. Ligands that produce biased signaling-the preferential activation of a signaling transducer in detriment of another-have been proposed as a strategy to dissociate therapeutic and adverse effects for a variety of G-protein coupled receptors. However, biased signaling at the CB1 receptor is poorly understood due to a lack of strongly biased agonists. Here, we review studies that have investigated the biased signaling profile of classical cannabinoid agonists and allosteric ligands, searching for a potential therapeutic advantage of CB1 biased signaling in different pathological states. Agonist and antagonist bound structures of CB1 and proposed mechanisms of action of biased allosteric modulators are used to discuss a putative molecular mechanism for CB1 receptor activation and biased signaling. Current studies suggest that allosteric binding sites on CB1 can be explored to yield biased ligands that favor or hinder conformational changes important for biased signaling.
| S-EPMC8433814 | biostudies-literature
Project description:Cannabinoids produce their characteristic effects mainly by binding to two types of G-protein coupled receptors (GPCRs), the CB1 and CB2 cannabinoid receptors. The CB1 receptor is the main cannabinoid receptor in the central nervous system, and it participates in many brain functions. Recent studies showed that membrane potential may serve as a novel modulatory modality of many GPCRs. Here, we used Xenopus oocytes as an expression system to examine whether membrane potential modulates the activity of the CB1 receptor. We found that the potencies of the endocannabinoid 2-AG and the phytocannabinoid THC in activating the receptor are voltage dependent; depolarization enhanced the potency of these agonists and decreased their dissociation from the receptor. This voltage dependence appears to be agonist dependent as the potency of the endocannabinoid anandamide (AEA) was voltage independent. The finding of this agonist-specific modulatory factor for the CB1 receptor may contribute to our future understanding of various physiological functions mediated by the endocannabinoid system.
| S-EPMC9592857 | biostudies-literature
Project description:Nicotine, the main psychoactive component of tobacco, and (-)-Δ(9)-tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis, play major roles in tobacco and marijuana dependence as reinforcers of drug-seeking and drug-taking behavior. Drugs that act as inverse agonists of cannabinoid CB1 receptors in the brain can attenuate the rewarding and abuse-related effects of nicotine and THC, but their clinical use is hindered by potentially serious side effects. The recently developed CB1-receptor neutral antagonists may provide an alternative therapeutic approach to nicotine and cannabinoid dependence. Here we compare attenuation of nicotine and THC reinforcement and reinstatement in squirrel monkeys by the CB1-receptor inverse agonist rimonabant and by the recently developed CB1-receptor neutral antagonist AM4113. Both rimonabant and AM4113 reduced two effects of nicotine and THC that play major roles in tobacco and marijuana dependence: (1) maintenance of high rates of drug-taking behavior, and (2) priming- or cue-induced reinstatement of drug-seeking behavior in abstinent subjects (models of relapse). In contrast, neither rimonabant nor AM4113 modified cocaine-reinforced or food-reinforced operant behavior under similar experimental conditions. However, both rimonabant and AM4113 reduced cue-induced reinstatement in monkeys trained to self-administer cocaine, suggesting the involvement of a common cannabinoid-mediated mechanism in the cue-induced reinstatement for different drugs of abuse. These findings point to CB1-receptor neutral antagonists as a new class of medications for treatment of both tobacco dependence and cannabis dependence.
| S-EPMC4946059 | biostudies-literature
Project description:Blockade of cannabinoid CB1 receptors has been reported to inhibit cocaine- or cocaine cue-induced reinstatement of drug seeking. However, the mechanisms underlying this action are poorly understood. Given the importance of dopamine, glutamate, and GABA in cocaine reward and relapse, we studied the effects of AM251 [N-(piperidin-1-yl)-5-(4-iodophonyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide], a novel highly selective CB1 receptor antagonist, on cocaine-primed reinstatement of drug-seeking behavior and on cocaine-induced changes in extracellular DA, glutamate, and GABA in the nucleus accumbens (NAc) under reinstatement conditions. We found that systemic administration of AM251 selectively inhibited cocaine-induced, but not sucrose plus sucrose cue-induced, reinstatement of reward-seeking behavior. AM251 alone did not trigger reinstatement. Local perfusion of AM251 into the NAc or the dorsal striatum also inhibited cocaine-triggered reinstatement. AM251 alone dose dependently elevated NAc glutamate in a voltage-dependent Na+ channel-dependent manner. AM251 did not affect NAc DA or GABA. Pretreatment with AM251 dose dependently inhibited cocaine-induced increases in NAc glutamate but not in DA. Blockade of NAc metabotropic glutamate mGluR2/3 receptors by LY341495 [(2S)-2-amino-2-[(1S,2S)-2-carboxycycloprop-1-yl]-3-(xanth-9-yl) propanoic acid] slightly facilitated cocaine-enhanced glutamate release but blocked the antagonism of cocaine-induced reinstatement by AM251. These data suggest the following: (1) CB1 receptors exert tonic inhibition over NAc glutamate release under cocaine-extinction conditions; (2) blockade of CB1 receptors by AM251 inhibits cocaine-enhanced NAc glutamate release and cocaine-triggered reinstatement; and (3) these effects appear to be mediated by activation of presynaptic mGluR2/3 autoreceptors secondary to AM251-induced increase (disinhibition) of NAc glutamate release.
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Project description:Cannabinoid Receptor Interacting Protein isoform 1b (CRIP1b) is known to interact with the CB1 receptor. Alternative splicing of the CNRIP1 gene produces CRIP1a and CRIP1b with a difference in the third exon only. Exons 1 and 2 encode for a functional domain in both proteins. CRIP1a is involved in regulating CB1 receptor internalization, but the function of CRIP1b is not very well characterized. Since there are significant identities in functional domains of these proteins, CRIP1b is a potential target for drug discovery. We report here predicted structure of CRIP1b followed by its interaction analysis with CB1 receptor by in-silico methods A number of complementary computational techniques, including, homology modeling, ab-initio and protein threading, were applied to generate three-dimensional molecular models for CRIP1b. The computed model of CRIP1b was refined, followed by docking with C terminus of CB1 receptor to generate a model for the CRIP1b- CB1 receptor interaction. The structure of CRIP1b obtained by homology modelling using RHO_GDI-2 as template is a sandwich fold structure having beta sheets connected by loops, similar to predicted CRIP1a structure. The best scoring refined model of CRIP1b in complex with the CB1 receptor C terminus peptide showed favourable polar interactions. The overall binding pocket of CRIP1b was found to be overlapping to that of CRIP1a. The Arg82 and Cys126 of CRIP1b are involved in the majority of hydrogen bond interactions with the CB1 receptor and are possible key residues required for interactions between the CB1 receptor and CRIP1b.
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Project description:Cannabinoid receptor 1 (CB1) is the principal target of ?9-tetrahydrocannabinol (THC), a psychoactive chemical from Cannabis sativa with a wide range of therapeutic applications and a long history of recreational use. CB1 is activated by endocannabinoids and is a promising therapeutic target for pain management, inflammation, obesity, and substance abuse disorders. Here, we present the 2.8 Å crystal structure of human CB1 in complex with AM6538, a stabilizing antagonist, synthesized and characterized for this structural study. The structure of the CB1-AM6538 complex reveals key features of the receptor and critical interactions for antagonist binding. In combination with functional studies and molecular modeling, the structure provides insight into the binding mode of naturally occurring CB1 ligands, such as THC, and synthetic cannabinoids. This enhances our understanding of the molecular basis for the physiological functions of CB1 and provides new opportunities for the design of next-generation CB1-targeting pharmaceuticals.
| S-EPMC5322940 | biostudies-literature
Project description:Brain cannabinoid (CB(1)) receptors are G-protein coupled receptors and belong to the rhodopsin-like subfamily. A homology model of the inactive state of the CB(1) receptor was constructed using the x-ray structure of beta(2)-adrenergic receptor (beta(2)AR) as the template. We used 105 ns duration molecular-dynamics simulations of the CB(1) receptor embedded in a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer to gain some insight into the structure and function of the CB(1) receptor. As judged from the root mean-square deviations combined with the detailed structural analyses, the helical bundle of the CB(1) receptor appears to be fully converged in 50 ns of the simulation. The results reveal that the helical bundle structure of the CB(1) receptor maintains a topology quite similar to the x-ray structures of G-protein coupled receptors overall. It is also revealed that the CB(1) receptor is stabilized by the formation of extensive, water-mediated H-bond networks, aromatic stacking interactions, and receptor-lipid interactions within the helical core region. It is likely that these interactions, which are often specific to functional motifs, including the S(N)LAxAD, D(E)RY, CWxP, and NPxxY motifs, are the molecular constraints imposed on the inactive state of the CB(1) receptor. It appears that disruption of these specific interactions is necessary to release the molecular constraints to achieve a conformational change of the receptor suitable for G-protein activation.
| S-EPMC2718272 | biostudies-literature