Tag Archives: CB1

Structure of an allosteric modulator bound to the CB1 cannabinoid receptor.

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Image result for nature chemical biology“The CB1 receptor mediates the central nervous system response to cannabinoids, and is a drug target for pain, anxiety and seizures.

CB1 also responds to allosteric modulators, which influence cannabinoid binding and efficacy.

To understand the mechanism of these compounds, we solved the crystal structure of CB1 with the negative allosteric modulator (NAM) ORG27569 and the agonist CP55940.

The structure reveals that the NAM binds to an extrahelical site within the inner leaflet of the membrane, which overlaps with a conserved site of cholesterol interaction in many G protein-coupled receptors (GPCRs).

The ternary structure with ORG27569 and CP55940 captures an intermediate state of the receptor, in which aromatic residues at the base of the agonist-binding pocket adopt an inactive conformation despite the large contraction of the orthosteric pocket.

The structure illustrates a potential strategy for drug modulation of CB1 and other class A GPCRs.”

https://www.ncbi.nlm.nih.gov/pubmed/31659318

https://www.nature.com/articles/s41589-019-0387-2

Cannabinoid receptor type 1 modulates the effects of polyunsaturated fatty acids on memory of stressed rats.

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 Publication Cover“Memory and GABAergic activity in the hippocampus of stressed rats improve after n-3 polyunsaturated fatty acid (PUFA) supplementation.

On the other hand, cannabinoid receptor type 1 (CB1) strongly regulates inhibitory neurotransmission in the hippocampus. Speculation about a possible relation between stress, endocannabinoids, and PUFAs.

Here, we examined whether the effects of PUFAs on memory of chronically stressed rats depends on pharmacological manipulation of CB1 receptors.

Memory improved in the stressed rats that were treated with AM251 and/or n-3 PUFAs. Supplementation with n-6 PUFAs did not affect memory of stressed rats, but co-treatment with AM251 improved it, while co-treatment with WIN55,212-2 did not affect memory.

Our results demonstrate that activity of the CB1 receptors may modulate the effects of PUFAs on memory of stressed rats. This study suggests that endocannabinoids and PUFAs can both become a singular system by being self-regulated in limbic areas, so they control the effects of stress on the brain.”

https://www.ncbi.nlm.nih.gov/pubmed/31637966

https://www.tandfonline.com/doi/abs/10.1080/1028415X.2019.1659561?journalCode=ynns20

The Endocannabinoid System as a Window Into Microglial Biology and Its Relationship to Autism.

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Image result for frontiers in cellular neuroscience“Microglia are the resident, innate immune cells of the central nervous system (CNS) and are critical in managing CNS injuries and infections. Microglia also maintain CNS homeostasis by influencing neuronal development, viability, and function. However, aberrant microglial activity and phenotypes are associated with CNS pathology, including autism spectrum disorder (ASD). Thus, improving our knowledge of microglial regulation could provide insights into the maintenance of CNS homeostasis as well as the prevention and treatment of ASD.

Control of microglial activity is in part overseen by small, lipid-derived molecules known as endogenous cannabinoids (endocannabinoids). Endocannabinoids are one component of the endocannabinoid system (ECS), which also includes the enzymes that metabolize these ligands, in addition to cannabinoid receptor 1 (CB1) and 2 (CB2).

Interestingly, increased ECS signaling leads to an anti-inflammatory, neuroprotective phenotype in microglia. Here, we review the literature and propose that ECS signaling represents a largely untapped area for understanding microglial biology and its relationship to ASD, with special attention paid to issues surrounding the use of recreational cannabis (marijuana). We also discuss major questions within the field and suggest directions for future research.”

https://www.ncbi.nlm.nih.gov/pubmed/31619967

“Microglial activity can be modulated by eCB signaling, which makes the ECS a potentially forceful tool in the prevention and management of CNS dysfunction.”

https://www.frontiersin.org/articles/10.3389/fncel.2019.00424/full

Disease associated polymorphisms within the conserved ECR1 enhancer differentially regulate the tissue specific activity of the cannabinoid-1 receptor gene promoter; implications for cannabinoid pharmacogenetics.

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Publication cover image“Cannabinoid receptor-1 (CB1) represents a potential drug target against conditions that include obesity and substance abuse. However, drug trials targeting CB1 (encoded by the CNR1 gene) have been compromised by differences in patient response.

Towards addressing the hypothesis that genetic changes within the regulatory regions controlling CNR1 expression contribute to these differences, we characterised the effects of disease associated allelic variation within a conserved regulatory sequence (ECR1) in CNR1 intron 2 that had previously been shown to modulate cannabinoid response, alcohol intake and anxiety-like behaviour.

We used primary cell analysis of reporters carrying different allelic variants of the human ECR1 and found that human specific C-allele variants of ECR1 (ECR1(C)) drove higher levels of CNR1prom activity in primary hippocampal cells than did the ancestral T-allele and demonstrated a differential response to CB1 agonism.

We further demonstrate a role for the AP-1 transcription factor in driving higher ECR1(C) activity and evidence that the ancestral t-allele variant of ECR1 interacted with higher affinity with the insulator binding factor CTCF. The cell-specific approaches used in our study represent an important step in gaining a mechanistic understanding the roles of non-coding polymorphic variation in disease and in the increasingly important field of cannabinoid pharmacogenetics.”

https://www.ncbi.nlm.nih.gov/pubmed/31608546

https://onlinelibrary.wiley.com/doi/abs/10.1002/humu.23931

CB1 enhanced the osteo/dentinogenic differentiation ability of periodontal ligament stem cells via p38 MAPK and JNK in an inflammatory environment.

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Publication cover image

“Periodontitis is an inflammatory immune disease that causes periodontal tissue loss. Inflammatory immunity and bone metabolism are closely related to periodontitis.

The cannabinoid receptor I (CB1) is an important constituent of the endocannabinoid system and participates in bone metabolism and inflammation tissue healing.

It is unclear whether CB1 affects the mesenchymal stem cell (MSC) function involved in periodontal tissue regeneration.

In this study, we revealed the role and mechanism of CB1 in the osteo/dentinogenic differentiation of periodontal ligament stem cells (PDLSCs) in an inflammatory environment.

CONCLUSIONS:

CB1 was able to enhance the osteo/dentinogenic differentiation ability of PDLSCs via p38 MAPK and JNK signalling in an inflammatory environment, which might be a potential target for periodontitis treatment.”

https://www.ncbi.nlm.nih.gov/pubmed/31599069

“In conclusion, our findings revealed that CB1 could activate the osteo/dentinogenic differentiation potential of PDLSCs under inflammatory conditions. Our results clarified the potential role and mechanism of CB1 in PDLSCs under inflammatory conditions and provide candidate targets for enhancing MSC function and the treatment of periodontitis.”

https://onlinelibrary.wiley.com/doi/full/10.1111/cpr.12691

Cannabinoid Receptor Type 1 and Its Role as an Analgesic: An Opioid Alternative?

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 Publication Cover“Understanding how the body regulates pain is fundamental to develop rational strategies to combat the growing prevalence of chronic pain states, opioid dependency, and the increased financial burden to the medical care system.

Pain is the most prominent reason why Americans seek medical attention and extensive literature has identified the importance of the endocannabinoid pathway in controlling pain. Modulation of the endocannabinoid system offers new therapeutic opportunities for the selective control of excessive neuronal activity in several pain conditions (acute, inflammatory, chronic, and neuropathic).

Cannabinoids have a long history of medicinal use and their analgesic properties are well documented; however, there are major impediments to understanding cannabinoid pain modulation.

One major issue is the presence of psychotropic side effects associated with D9-tetrahydrocannabinol (THC) or synthetic derivatives, which puts an emphatic brake on their use. This dose-limiting effect prevents the appropriate degree of analgesia .

Animal studies have shown that the psychotropic effects are mediated via brain cannabinoid type 1 (CB1) receptors, while analgesic activity in chronic pain states may be mediated via CB1R action in the spinal cord, brainstem, peripheral sensory neurons, or immune cells.

The development of appropriate therapies is incumbent on our understanding of the role of peripheral versus central endocannabinoid-driven analgesia. Recent physiological, pharmacological, and anatomical studies provide evidence that one of the main roles of the endocannabinoid system is the regulation of gamma-aminobutyric acid (GABA) and/or glutamate release.

This article will review this evidence in the context of its implications for pain. We first provide a brief overview of CB1R’s role in the regulation of nociception, followed by a review of the evidence that the peripheral endocannabinoid system modulates nociception.

We then look in detail at regulation of central-mediated analgesia, followed up with evidence that cannabinoid mediated modulation of pain involves modulation of GABAergic and glutamatergic neurotransmission in key brain regions. Finally, we discuss cannabinoid action on non-neuronal cells in the context of inflammation and direct modulation of neurons.

This work stands to reveal long-standing controversies in the cannabinoid analgesia area that have had an impact on failed clinical trials and implementation of therapeutics targeting this system.”

https://www.ncbi.nlm.nih.gov/pubmed/31596190

https://www.tandfonline.com/doi/abs/10.1080/15504263.2019.1668100?journalCode=wjdd20

Cannabinoid receptor 1 knockout alleviates hepatic steatosis by downregulating perilipin 2.

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Image result for LI laboratory investigations journal“The endocannabinoid (EC) system has been implicated in the pathogenesis of several metabolic diseases, including nonalcoholic fatty liver disease (NAFLD).

With the current study we aimed to verify the modulatory effect of endocannabinoid receptor 1 (CB1)-signaling on perilipin 2 (PLIN2)-mediated lipophagy.

In conclusion, these results suggest that loss of CB1 signaling leads to reduced PLIN2 abundance, which triggers lipophagy. Our new findings about the association between CB1 signaling and PLIN2 may stimulate translational studies analyzing new diagnostic and therapeutic options for NAFLD.”

https://www.ncbi.nlm.nih.gov/pubmed/31570772

“In conclusion, we demonstrated that the CB1 receptor knockout in vivo and pharmacologic antagonization of CB1 in cell culture decreased PLIN2 expression, which might be an essential step in lipid breakdown. Thus, pharmacologic modulation of the CB1-PLIN2 axis might represent a novel therapeutic approach for the treatment of steatosis.”

https://www.nature.com/articles/s41374-019-0327-5

Intermittent ethanol exposure during adolescence impairs cannabinoid type 1 receptor-dependent long-term depression and recognition memory in adult mice.

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Image result for neuropsychopharmacology“Binge drinking is a significant problem in adolescent populations, and because of the reciprocal interactions between ethanol (EtOH) consumption and the endocannabinoid (eCB) system, we sought to determine if adolescent EtOH intake altered the localization and function of the cannabinoid 1 (CB1) receptors in the adult brain.

We also examined a form of excitatory long-term depression that is dependent on CB1 receptors (eCB-eLTD) and found that it was completely lacking in the animals that consumed EtOH during adolescence.

These findings indicate that repeated exposure to EtOH during adolescence leads to long-term deficits in CB1 receptor expression, eCB-eLTD, and reduced recognition memory, but that these functional deficits can be restored by treatments that increase endogenous 2-arachidonoylglycerol.”

https://www.ncbi.nlm.nih.gov/pubmed/31569197

https://www.nature.com/articles/s41386-019-0530-5

Opposed Cannabinoid 1 receptor (CB1R) expression in the prefrontal cortex vs. nucleus accumbens is associated with alcohol consumption in male rats.

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Brain Research“Abusive alcohol consumption is a health problem, worldwide.

There is extensive literature indicating that cannabinoid 1 receptor (CB1R) plays a crucial role in mediating alcohol’s reward effects.

Maternal care deprivation (MCD) is a reliable rodent model of early life stress that leads to high levels of anxiety and alterations in motivation, which may increase vulnerability to alcohol consumption.

The present study researched whether anxiety-like behaviors and the level of motivation for a natural reward, and CB1R expression in the prefrontal cortex (PFC) and nucleus accumbens (NAcc) can predict alcohol consumption in non-MCD and MCD male rats.

Results indicate that MCD increases anxiety-like behaviors, i.e., reduces time in open arms in the elevated plus maze and increases alcohol intake. In turn, the motivation for a palatable reward, i.e., a chocolate flavored pellet, was not affected by MCD.

MCD reduces CB1R expression in the PFC and increases it in the NAcc. Hence, both higher anxiety-like behaviors and higher CB1R expression in the NAcc and lower CB1R expression in the PFC are associated with higher alcohol intake.

These results suggest that early life adverse experiences induce a reprogramming of the brain’s endocannabinoid system that very likely contributes to making the brain vulnerable to develop alcohol abuse and dependence.”

https://www.ncbi.nlm.nih.gov/pubmed/31568767

https://www.sciencedirect.com/science/article/abs/pii/S0006899319305396?via%3Dihub

Targeting Cannabinoid 1 and Delta Opioid Receptor Heteromers Alleviates Chemotherapy-Induced Neuropathic Pain.

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“Cannabinoid 1 (CB1R) and delta opioid receptors (DOR) associate to form heteromers that exhibit distinct pharmacological properties.

Not much is known about CB1R-DOR heteromer location or signaling along the pain circuit in either animal models or patients with chemotherapy-induced peripheral neuropathy (CIPN).

Here, we use paclitaxel to induce CIPN in mice and confirm the development of mechanical allodynia.

Together, these results imply that CB1R-DOR heteromers upregulated during CIPN-associated mechanical allodynia could serve as a potential target for treatment of neuropathic pain including CIPN.”

https://www.ncbi.nlm.nih.gov/pubmed/31565698

https://pubs.acs.org/doi/10.1021/acsptsci.9b00008