Tag Archives: cannabinoid receptors

Functional selectivity at G-protein coupled receptors: Advancing cannabinoid receptors as drug targets.

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“The phenomenon of functional selectivity, whereby a ligand preferentially directs the information output of a G-protein coupled receptor (GPCR) along (a) particular effector pathway(s) and away from others, has redefined traditional GPCR signaling paradigms to provide a new approach to structure-based drug design.

The two principal cannabinoid receptors (CBRs) 1 and 2 belong to the class-A GPCR subfamily and are considered tenable therapeutic targets for several indications. Yet conventional orthosteric ligands (agonists, antagonists/inverse agonists) for these receptors have had very limited clinical utility due to their propensity to incite on-target adverse events. Chemically distinct classes of cannabinergic ligands exhibit signaling bias at CBRs toward individual subsets of signal transduction pathways.

In this review, we discuss the known signaling pathways regulated by CBRs and examine the current evidence for functional selectivity at CBRs in response to endogenous and exogenous cannabinergic ligands as biased agonists. We further discuss the receptor and ligand structural features allowing for selective activation of CBR-dependent functional responses. The design and development of biased ligands may offer a pathway to therapeutic success for novel CBR-targeted drugs.”

https://www.ncbi.nlm.nih.gov/pubmed/27890725

The endogenous lipid N-arachidonoyl glycine is hypotensive and nitric oxide-cGMP-dependent vasorelaxant.

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“N-arachidonoyl glycine (NAGLY), is the endogenous lipid that activates the G protein-couple receptor 18 (GPR18) with vasodilatory activity in resistance arteries. This study investigates its hemodynamic effects and mechanisms of vasorelaxation.

NAGLY is an endothelium-dependent vasodilator and hypotensive lipid. The vasorelaxation is predominantly via activation of nitric oxide-cGMP pathway and NCX and probably mediated by the “endothelial anandamide” receptor, while the hypotensive effect of NAGLY appears not to involve the anandamide receptor. NAGLY also potentiates carbachol-induced vasorelaxation, the mechanism of which might involve stimulation of NO release.”

https://www.ncbi.nlm.nih.gov/pubmed/27890711

The cannabinoid receptor 1 gene (CNR1) and multiple sclerosis: an association study in two case-control groups from Spain.

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“Different studies point to the implication of the endocannabinoid system in multiple sclerosis (MS) and animal models of MS.

The purpose of this study was to evaluate a possible association of MS with polymorphic markers at the CNR1 gene, encoding the cannabinoid 1 (CB(1)) receptor.

We have performed a genetic analysis of an AAT repeat microsatellite localized in the downstream region of the CNR1 gene, in two case-control groups of MS patients and healthy controls (HC) from Spain (Madrid and Bilbao).

MSpatients with primary progressive MS (PPMS) had more commonly long ((AAT) > or = (13)) alleles and genotypes with a significant difference for genotype 7/8 in Madrid (p = 0.043) and in the sum of both groups (p = 0.016); short alleles were less frequently found in PPMS with a significant difference for allele 5 in the analysis of both groups together (p = 0.039).

In patients with relapsing MS, no consistent differences in allele and genotype distribution were found. Disease severity and progression was unrelated to AAT repeat variations.

In conclusion, long (AAT) > or = (13) CNR1 genotypes could behave as risk factors for PPMS.”

 https://www.ncbi.nlm.nih.gov/pubmed/20007426

Biased Agonism of Three Different Cannabinoid Receptor Agonists in Mouse Brain Cortex

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“Cannabinoid receptors are able to couple to different families of G proteins when activated by an agonist drug. It has been suggested that different intracellular responses may be activated depending on the ligand.

The goal of the present study was to characterize the pattern of G protein subunit stimulation triggered by three different cannabinoid ligands, Δ9-THC, WIN55212-2, and ACEA in mouse brain cortex.

Results show that, in mouse brain cortex, cannabinoid agonists are able to significantly stimulate not only the classical inhibitory Gαi/osubunits but also other G subunits like Gαz, Gαq/11, and Gα12/13. Moreover, the specific pattern of G protein subunit activation is different depending on the ligand.

In conclusion, our results demonstrate that, in mice brain native tissue, different exogenous cannabinoid ligands are able to selectively activate different inhibitory and non-inhibitory Gα protein subtypes, through the activation of CB1 and/or CB2 receptors.

Results of the present study may help to understand the specific molecular pathways involved in the pharmacological effects of cannabinoid-derived drugs.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5095132/

The cannabinoid beta-caryophyllene (BCP) induces neuritogenesis in PC12 cells by a cannabinoid-receptor-independent mechanism.

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“Beta-caryophyllene (BCP) is a phytocannabinoid whose neuroprotective activity has been mainly associated with selective activation of cannabinoid-type-2 (CB2) receptors, inhibition of microglial activation and decrease of inflammation.

Here, we addressed the potential of BCP to induce neuritogenesis in PC12 cells, a model system for primary neuronal cells that express trkA receptors, respond to NGF and do not express CB2 receptors.

We demonstrated that BCP increases the survival and activates the NGF-specific receptor trkA in NGF-deprived PC12 cells, without increasing the expression of NGF itself. The neuritogenic effect of BCP in PC12 cells was abolished by k252a, an inhibitor of the NGF-specific receptor trkA. Accordingly, BCP did not induce neuritogenesis in SH-SY5Y neuroblastoma cells, a neuronal model that does not express trkA receptors and do not respond to NGF.

Additionally, we demonstrated that BCP increases the expression of axonal-plasticity-associated proteins (GAP-43, synapsin and synaptophysin) in PC12 cells. It is known that these proteins are up-regulated by NGF in neurons and neuron-like cells, such as PC12 cells.

Altogether, these findings suggest that BCP activates trka receptors and induces neuritogenesis by a mechanism independent of NGF or cannabinoid receptors. This is the first study to show such effects of BCP and their beneficial role in neurodegenerative processes should be further investigated.”

https://www.ncbi.nlm.nih.gov/pubmed/27871898

“β-caryophyllene (BCP) is a common constitute of the essential oils of numerous spice, food plants and major component in Cannabis.”  http://www.ncbi.nlm.nih.gov/pubmed/23138934

“The oral intake of this dietary cannabinoid with vegetable food could be advantageous in the daily routine clinical practice over synthetic cannabinoid agonists.” http://www.europeanneuropsychopharmacology.com/article/S0924-977X(13)00302-7/fulltext

Cannabinoid Receptor 2 Functional Variant Contributes to the Risk for Pediatric Inflammatory Bowel Disease.

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“We conducted a case-control association analysis to establish the role of a common CB2 functional variant, Q63R, in the susceptibility to inflammatory bowel disease (IBD).

Endocannabinoids may limit intestinal inflammation through cannabinoid receptor 1 and/or 2 (CB1, CB2).

The CB2-Q63R variant contributes to the risk for pediatric IBD, in particular CD. The R63 variant is associated with a more severe phenotype in both UC and CD.

Taken together, our data point toward the involvement of the CB2 receptor in the pathogenesis and clinical features of pediatric IBD.”

https://www.ncbi.nlm.nih.gov/pubmed/27875353

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

Endocannabinoid system in sexual motivational processes: is it a novel therapeutic horizon?

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“The endocannabinoid system (ECS), which is composed of the cannabinoid receptors types 1 and 2 (CB1 and CB2) for marijuana’s psychoactive ingredient Δ9-tetrahydrocannabinol (Δ9-THC), the endogenous ligands (AEA and 2-AG) and the enzymatic systems involved in their biosynthesis and degradation, recently emerged as important modulator of emotional and non-emotional behaviors.

For centuries, in addition to its recreational actions, several contradictory claims regarding the effects of Cannabis use in sexual functioning and behavior (e.g. aphrodisiac vs anti-aphrodisiac) of both sexes have been accumulated. The identification of Δ9-THC and later on, the discovery of the ECS have opened a potential therapeutic target for sexual dysfunctions, given the partial efficacy of current pharmacological treatment.

In agreement with the bidirectional modulation induced by cannabinoids on several behavioral responses, the endogenous cannabinoid AEA elicited biphasic effects on sexual behavior as well. The present article reviews current available knowledge on herbal, synthetic and endogenous cannabinoids with respect to the modulation of several aspects of sexuality in preclinical and human studies, highlighting their therapeutic potential.”

https://www.ncbi.nlm.nih.gov/pubmed/27884725

“Cannabis As An Aphrodisiac? The Evidence Is Mounting”  https://www.civilized.life/articles/aphrodisiac-evidence-is-mounting/

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

Modulation of Type-1 and Type-2 Cannabinoid Receptors by Saffron in a Rat Model of Retinal Neurodegeneration.

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“Experimental studies demonstrated that saffron (Crocus sativus) given as a dietary supplement counteracts the effects of bright continuous light (BCL) exposure in the albino rat retina, preserving both morphology and function and probably acting as a regulator of programmed cell death.

The purpose of this study was to ascertain whether the neuroprotective effect of saffron on rat retina exposed to BCL is associated with a modulation of the endocannabinoid system (ECS).

These data suggest that BCL modulates only distinct ECS elements like CB1 and CB2, and that saffron and cannabinoid receptors could share the same mechanism in order to afford retinal protection.”

 https://www.ncbi.nlm.nih.gov/pubmed/27861558