“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.”
“Previous studies have shown that a cytosine (C) to thymine (T) single nucleotide polymorphism (SNP) of the human cannabinoid receptor 1 (CNR1) gene is associated with positive emotional processing.
C allele carriers are more sensitive to positive emotional stimuli including happiness. The effects of several gene polymorphisms related to sensitivity to emotional stimuli, such as that in the serotonin transporter gene-linked polymorphic region (5HTTLPR), on emotional processing have been reported to differ among cultures-e.g., between those that are independent and interdependent. Thus, we postulated that the effects of the CNR1 genotype on happiness might differ among different cultures because the concept of happiness varies by culture.
We recruited healthy male and female young adults in Japan, where favorable external circumstances determine the concept of happiness, and Canada, where the concept of happiness centers on positive inner feelings, and compared the effects of the CNR1 genotype on both subjective happiness levels (self-evaluation as being a happy person) and situation-specific happiness (happy feelings accompanying various positive events) by using a questionnaire.
We found that the effect of CNR1 on subjective happiness was different between the Japanese and Canadian groups. The subjective happiness level was the highest in Japanese individuals with the CC genotype, whereas in Canadian participants, it was the highest in individuals with the TT genotype. Furthermore, the effects of CNR1 genotype on situation-specific happiness were also different between the groups. Happiness accompanied with being surrounded by happy people was the highest among Japanese individuals with the CC genotype, whereas among Canadian individuals, it was the highest in TT genotype carriers.
These findings suggest that culture and CNR1 polymorphism interact to influence the perception of happiness.”
“Targeting peripheral CB1R is desirable for the treatment of metabolic syndromes without adverse neuropsychiatric effects.
We previously reported a human hCB1b isoform that is selectively enriched in pancreatic beta-cells and hepatocytes, providing a potential peripheral therapeutic hCB1R target. It is unknown whether there are peripherally enriched mouse and rat CB1R (mCB1 and rCB1, respectively) isoforms.
In this study, we found no evidence of peripherally enriched rodent CB1 isoforms; however, some mCB1R isoforms are absent in peripheral tissues. We show that the mouse Cnr1 gene contains six exons that are transcribed from a single promoter. We found that mCB1A is a spliced variant of extended exon 1 and protein-coding exon 6; mCB1B is a novel spliced variant containing unspliced exon 1, intron 1, and exon 2, which is then spliced to exon 6; and mCB1C is a spliced variant including all 6 exons.
Using RNAscope in situ hybridization, we show that the isoforms mCB1A and mCB1B are expressed at a cellular level and colocalized in GABAergic neurons in the hippocampus and cortex. RT-qPCR reveals that mCB1A and mCB1B are enriched in the brain, while mCB1B is not expressed in the pancreas or the liver. Rat rCB1R isoforms are differentially expressed in primary cultured neurons, astrocytes, and microglia.
We also investigated modulation of Cnr1 expression by insulin in vivo and carried out in silico modeling of CB1R with JD5037, a peripherally restricted CB1R inverse agonist, using the published crystal structure of hCB1R.
The results provide models for future CB1R peripheral targeting.”
“The endocannabinoid system plays a role in regulating bone mass and bone cell activity and inactivation of the type 1 (Cnr1) or type 2 (Cnr2) cannabinoid receptors influences peak bone mass and age-related bone loss. As the Cnr1 and Cnr2 receptors have limited homology and are activated by different ligands, we have evaluated the effects of combined deficiency of Cnr1 and 2 receptors (Cnr1/2-/- ) on bone development from birth to old age and studied ovariectomy induced bone loss in female mice. The Cnr1/2-/- mice had accelerated bone accrual at birth when compared with wild type littermates, and by 3 months of age, they had higher trabecular bone mass. They were also significantly protected against ovariectomy-induced bone loss due to a reduction in osteoclast number. The Cnr1/2-/- mice had reduced age-related bone loss when compared with wild-type due to a reduction in osteoclast number. Although bone formation was reduced and bone marrow adiposity increased in Cnr1/2-/- mice, the osteoclast defect outweighed the reduction in bone formation causing preservation of bone mass with aging. This contrasts with the situation previously reported in mice with inactivation of the Cnr1 or Cnr2 receptors individually where aged-related bone loss was greater than in wild-type. We conclude that the Cnr1 and Cnr2 receptors have overlapping but nonredundant roles in regulating osteoclast and osteoblast activities. These observations indicate that combined inhibition of Cnr1 and Cnr2 receptors may be beneficial in preventing age-related bone loss, whereas blockade of individual receptors may be detrimental.”
“Multiple sclerosis (MS) is a chronic demyelinating central nervous system (CNS) disease that involve oligodendrocyte loss and failure to remyelinate damaged brain areas causing a progressive neurological disability.
Studies in MS mouse model suggest that cannabinoids ameliorate symptoms as spasticity, tremor and pain reducing inflammation via cannabinoid-mediated system.
The aim of our study is to investigate the changes in cannabinoid type 1 (CNR1) and 2 (CNR2) receptors mRNA expression levels and promoter methylation in peripheral blood mononuclear cells (PBMCs) of MS secondary progressive (MSS-SP) patients treated with Sativex®.
These results suggest that the different expression of cannabinoid receptors by Sativex® treatment in leukocytes might be regulated through a molecular mechanism that involve interferon modulation.”
“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 progressiveMS (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.”
“The central cannabinoid receptor (CB1) mediates the pharmacological activities of cannabis, the endogenous agonist anandamide and several synthetic agonists.
The cloning of the human cannabinoid receptor (CNR1) gene facilitates molecular genetic studies in disorders like Gilles de la Tourette syndrome (GTS), obsessive compulsive disorder (OCD), Parkinsons disease, Alzheimers disease or other neuro psychiatric or neurological diseases, which may be predisposed or influenced by mutations or variants in the CNR1 gene.
We detected a frequent silent mutation (1359G–>A) in codon 453 (Thr) of the CNR1 gene that turned out to be a common polymorphism in the German population. Allele frequencies of this polymorphism are 0.76 and 0.24, respectively.
We developed a simple and rapid polymerase chain reaction (PCR)-based assay by artificial creation of a Msp I restriction site in amplified wild-type DNA (G-allele), which is destroyed by the silent mutation (A-allele).
The intragenic CNR1 polymorphism 1359(G/A) should be useful for association studies in neuro psychiatric disorders which may be related to anandamide metabolism disturbances.”
“Nicotine withdrawal-related disruption of cognitive control may contribute to the reinforcement of tobacco use.
Identification of gene variants that predict this withdrawal phenotype may lead to tailored pharmacotherapy for smoking cessation.
Variation on the cannabinoid receptor 1 gene (CNR1) has been related to nicotine dependence, and CNR1 antagonists may increase attention and memory functioning.
The current findings suggest potential efficacy of cannabinoid RECEPTOR antagonism as a pharmacotherapy approach for smoking cessation among individuals who exhibit greater nicotine withdrawal-related cognitive disruption.”