Tag Archives: inverse agonists

Binding Site Characterization of AM1336, a Novel Covalent Inverse Agonist at Human Cannabinoid 2 Receptor, Using Mass Spectrometric Analysis.

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“Cannabinoid 2 receptor (CB2R), a Class A G-protein coupled receptor (GPCR), is a promising drug target in a wide array of pathological conditions. Rational drug design has been hindered due to our poor understanding of the structural features involved in ligand binding. Binding of a high-affinity biarylpyrazole inverse agonist AM1336 to a library of the human CB2 receptor (hCB2R) cysteine-substituted mutants provided indirect evidence that two cysteines in transmembrane helix-7 (H7) were critical for the covalent attachment. Here, we used proteomics analysis of the hCB2R with bound AM1336 to directly identify peptides with covalently attached ligand and applied in-silico modeling for visualization of the ligand-receptor interactions. The hCB2R, with affinity tags (FlaghCB2His6), was produced in a baculovirus-insect cell expression system and purified as a functional receptor using immunoaffinity chromatography. Using mass spectrometry-based bottom-up proteomic analysis of the hCB2R-AM1336 we identified a peptide with AM1336 attached to the cysteine C284(7.38) in H7. The hCB2R homology model in lipid bilayer accommodated covalent attachment of AM1336 to C284(7.38), supporting both biochemical and mass spectrometric data. This work consolidates proteomics data and in-silico modeling, and integrates with our ligand-assisted protein structure (LAPS) experimental paradigm to assist in structure-based design of cannabinoid antagonist/inverse agonists.”

https://www.ncbi.nlm.nih.gov/pubmed/28374590

Blockade of Nicotine and Cannabinoid Reinforcement and Relapse by a Cannabinoid CB1-Receptor Neutral Antagonist AM4113 and Inverse Agonist Rimonabant in Squirrel Monkeys.

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“Nicotine, the main psychoactive component of tobacco, and (-)-Δ9-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…

Recently-developed CB1-receptor neutral antagonists may provide an alternative therapeutic approach to nicotine and cannabinoid dependence.

These findings point to CB1-receptor neutral antagonists as a new class of medications for treatment of both tobacco dependence and cannabis dependence.”

http://www.ncbi.nlm.nih.gov/pubmed/26888056

The endocannabinoid system in obesity and type 2 diabetes.

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“Endocannabinoids (ECs) are defined as endogenous agonists of cannabinoid receptors type 1 and 2 (CB1 and CB2). ECs, EC anabolic and catabolic enzymes and cannabinoid receptors constitute the EC signalling system. This system participates in the control of lipid and glucose metabolism at several levels, with the possible endpoint of the accumulation of energy as fat.

Following unbalanced energy intake, however, the EC system becomes dysregulated, and in most cases overactive, in several organs participating in energy homeostasis, particularly, in intra-abdominal adipose tissue. This dysregulation might contribute to excessive visceral fat accumulation and reduced adiponectin release from this tissue, and to the onset of several cardiometabolic risk factors that are associated with obesity and type 2 diabetes.

This phenomenon might form the basis of the mechanism of action of CB1 antagonists/inverse agonists, recently developed by several pharmaceutical companies as adjuvants to lifestyle modification for weight reduction, glycaemic control and dyslipidaemia in obese and type 2 diabetes patients.

It also helps to explain why some of the beneficial actions of these new therapeutics appear to be partly independent from weight loss.”

http://www.ncbi.nlm.nih.gov/pubmed/18563385

http://www.thctotalhealthcare.com/category/obesity-2/

http://www.thctotalhealthcare.com/category/diabetes/

Minireview: From the Bench, Toward the Clinic: Therapeutic Opportunities for Cannabinoid Receptor Modulation.

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The effects of cannabinoids have been known for centuries and over the past several decades two G-protein coupled receptors, CB1 and CB2, have been identified that are responsible for their activity.

Endogenous lipid-derived cannabinergic agents have been found, biosynthetic and catabolic machinery characterized, and synthetic agents have been designed to modulate these receptors.

Selective agents including agonists, antagonists, inverse agonists and novel allosteric modulators targeting either CB1 or CB2 have been developed to inhibit or augment their basal tone.

As a result, the role these receptors play in human physiology and their potential therapeutic applications in disease states are being elucidated.

The CB1 receptor while ubiquitous is densely expressed in the brain and CB2 is largely found on cells of immune origin.

This minireview highlights the role of CB1 in excitotoxic assaults in the brain and its potential to limit addiction liability.

In addition, it will examine the relationship between receptor activity and stimulation of insulin release from pancreatic β-cells, insulin resistance and feeding behavior leading toward obesity.

The role of CB2 in the neuropathology of amyotrophic lateral sclerosis and in the central manifestations of chronic HIV infection potentially converges at inflammatory cell activation thereby providing an opportunity for intervention.

Lastly, CB2 modulation is discussed in the context of an experimental model of post-menopausal osteoporosis.

Achieving exquisite receptor selectivity and elucidating the mechanisms underlying receptor inhibition and activation will be essential for the development of the next generation of cannabinergic-based therapeutic agents.”

Updating the chemistry and biology of cannabinoid CB2 receptor-specific inverse agonists.

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“The cannabinoid CB(2) receptor continues to be an intriguing target for the potential therapeutic benefit of cannabinoids. Because this receptor is significantly found outside the brain, compounds specific for the CB(2) receptor may be free of the side effects that have plagued cannabinoid CB(1) receptor-based therapeutics.

In this review, we will discuss a class of compounds which modulate the constitutive activity of the cannabinoid CB(2) receptor, the inverse agonists. We will discuss recent chemical advances that provide new compounds to investigate the biology based on this pharmacology. We will then discuss new biology associated with the cannabinoid CB(2) receptor for hints of how these compounds can best be utilized in vivo.”

http://www.ncbi.nlm.nih.gov/pubmed/20370714

Peripherally restricted CB1 receptor blockers.

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“Antagonists (inverse agonists) of the cannabinoid-1 (CB1) receptor showed promise as new therapies for controlling obesity and related metabolic function/liver disease.

These agents, representing diverse chemical series, shared the property of brain penetration due to the initial belief that therapeutic benefit was mainly based on brain receptor interaction. However, undesirable CNS-based side effects of the only marketed agent in this class, rimonabant, led to its removal, and termination of the development of other clinical candidates soon followed. Re-evaluation of this approach has focused on neutral or peripherally restricted (PR) antagonists.

Supporting these strategies, pharmacological evidence indicates most if not all of the properties of globally acting agents may be captured by molecules with little brain presence. Methodology that can be used to eliminate BBB penetration and the means (in vitro assays, tissue distribution and receptor occupancy determinations, behavioral paradigms) to identify potential agents with little brain presence is discussed.

Focus will be on the pharmacology supporting the contention that reported agents are truly peripherally restricted. Notable examples of these types of compounds are: TM38837 (structure not disclosed); AM6545 (8); JD5037 (15b); RTI-12 (19).”

http://www.ncbi.nlm.nih.gov/pubmed/23902803

Anti-inflammatory cannabinoids in diet: Towards a better understanding of CB(2) receptor action?

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“The endocannabinoid system is an ancient lipid signaling network which in mammals modulates neuronal functions, inflammatory processes, and is involved in the aetiology of certain human lifestyle diseases, such as Crohn’s disease, atherosclerosis and osteoarthritis.

The system is able to downregulate stress-related signals that lead to chronic inflammation and certain types of pain, but it is also involved in causing inflammation-associated symptoms, depending on the physiological context.

The cannabinoid type-2 (CB2) receptor, which unlike the CB1 receptor does not induce central side effects, has been shown to be a promising therapeutic target. While CB1 receptor antagonists/inverse agonists are of therapeutic value, also CB2 receptor ligands including agonists are of pharmacological interest.

 Although the endocannabinoid system is known to be involved in the regulation of energy homoeostasis and metabolism (mainly via CB1 receptors) there was hitherto no direct link between food intake and cannabinoid receptor activation. Our recent finding that beta-caryophyllene, a ubiquitous lipohilic plant natural product, selectively binds to the CB2 receptor and acts as a full agonist is unexpected…

In the case of the dietary natural product beta-caryophyllene, a full CB2 receptor-selective agonist in vitro, potent anti-inflammatory cannabimimetic effects are observed. Intriguingly, the lowest oral dose tested (5 mg/Kg) of this widespread and apparently non-toxic compound, which is also an FDA-approve food additive, was the most effective. Maybe this strengthens the hypothesis that beta-caryophyllene is indeed a dietary cannabinoid, thus inferring that by eating this compound the endocannabinoid system may be modulated in a beneficial way…”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2633791/

Cannabinoid CB1 receptor antagonists as potential pharmacotherapies for drug abuse disorders.

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Abstract

“Since the discovery of the cannabinoid CB1 receptor (CB1R) in 1988, and subsequently of the CB2 receptor (CB2R) in 1993, there has been an exponential growth of research investigating the functions of the endocannabinoid system. The roles of CB1Rs have been of particular interest to psychiatry because of their selective presence within the CNS and because of their association with brain-reward circuits involving mesocorticolimbic dopamine systems. One potential role that has become of considerable focus is the ability of CB1Rs to modulate the effects of the drugs of abuse. Many drugs of abuse elevate dopamine levels, and the ability of CB1R antagonists or inverse agonists to modulate these elevations has suggested their potential application as pharmacotherapies for treating drug abuse disorders. With the identification of the selective CB1R antagonist, rimonabant, in 1994, and subsequently of other CB1R antagonists, there has been a rapid expansion of research investigating their ability to modulate the effects of the drugs of abuse. This review highlights some of the preclinical and clinical studies that have examined the effects of CB1R antagonists under conditions potentially predictive of their therapeutic efficacy as treatments for drug abuse disorders.”

http://www.ncbi.nlm.nih.gov/pubmed/19367507

Current evidence supporting a role of cannabinoid CB1 receptor (CB1R) antagonists as potential pharmacotherapies for drug abuse disorders.

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Abstract

“Since the discovery of the cannabinoid CB1 receptor (CB1R) in 1988, and subsequently of the CB2 receptor (CB2R) in 1993, there has been an exponential growth of research investigating the functions of the endocannabinoid system. The roles of CB1Rs have been of particular interest to behavioral pharmacologists because of their selective presence within the central nervous system (CNS) and because of their association with brain-reward circuits involving mesocorticolimbic dopamine systems. One potential role that has become of considerable recent focus is the ability of CB1Rs to modulate the effects of drugs of abuse. Many drugs of abuse elevate dopamine levels, and the ability of CB1R antagonists or inverse agonists to attenuate these elevations has suggested their potential application as pharmacotherapies for treating drug abuse disorders. With the identification of the selective CB1R antagonist, SR141716, in 1994, and its subsequent widespread availability, there has been a rapid expansion of research investigating its ability to modulate the effects of drugs of abuse. The preliminary clinical reports of its success in retarding relapse in tobacco users have accelerated this expansion. This report critically reviews preclinical and clinical studies involving the ability of CB1R antagonists to attenuate the effects of drugs of abuse, while providing an overview of the neuroanatomical and neurochemical points of contact between the endocannabinoid system and systems mediating abuse-related effects.”

http://www.ncbi.nlm.nih.gov/pubmed/16148435

Cannabinoid receptor ligands: clinical and neuropharmacological considerations, relevant to future drug discovery and development.

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Abstract

“This review highlights some important advances that have taken place in cannabinoid research over the last four years. It focuses on novel ligands that are of interest either as experimental tools or as lead compounds for therapeutic agents and possible clinical applications for some of these ligands. The molecular targets for these compounds are various components of the system of endogenous cannabinoids (endocannabinoids) and receptors that together constitute the ‘endocannabinoid system’. These are CB(1) cannabinoid receptors that are present mainly on central and peripheral neurones, CB(2) cannabinoid receptors that are expressed predominantly by immune cells, the biochemical mechanisms responsible for the tissue uptake or metabolism of endocannabinoids and vanilloid receptors. Other cannabinoid receptor types may also exist. Recently developed ligands include potent and selective agonists for CB(1) and CB(2) receptors, a potent CB(2)-selective antagonist/inverse agonist and inhibitors of endocannabinoid uptake or metabolism. Future research should be directed at characterising the endocannabinoid system more completely and at obtaining more conclusive clinical data about the possible beneficial effects of cannabinoids as well as their adverse effects. There is also a need for improved cannabinoid formulations/modes of administration in the clinic and advances in this area should be facilitated by the recent development of a potent water-soluble CB(1)/CB(2) receptor agonist. A growing number of strategies for separating sought-after therapeutic effects of cannabinoid receptor agonists from the unwanted consequences of CB(1) receptor activation are now emerging and these are discussed at the end of this review.”

http://www.ncbi.nlm.nih.gov/pubmed/11060760