Cannabinoid receptor 1 (CNR1) gene polymorphisms in schizophrenia patients: Rs6454674 polymorphism is associated with disease severity

Objective: The endocannabinoid system contributes to the regulation of emotions, stress, memory, and cognition. It has been reported that endocannabinoids cause GABAergic inhibition and dopaminergic increase in the mesolimbic and nigrostriatal systems, thus playing a part in the neurobiology of schizophrenia. In this study, we investigate cannabinoid receptor 1 (CNR1) gene polymorphisms in schizophrenia patients. Methods: CNR1 gene polymorphisms were studied in 66 schizophrenia patients and 65 healthy controls. To obtain genomic DNA, proteinase K digestion and the salt-chloroform method were used. Clinical Global Impression severity scale (CGI-S) and Positive and Negative Syndrome Scale (PANSS) were administered to evaluate the severity of schizophrenia symptoms. CNR1 gene polymorphism was determined by using polymerase chain reaction (PCR), Restriction Fragment Length Polymorphism (RFLP), and Single Strand Conformation Polymorphism (SSCP) methods for the Rs6454674, Rs806368, and Rs1049353 sites.Results: There was no difference in CNR1 gene polymorphisms between schizophrenia patients and control groups (Rs6454674 T/G; p=0.973, Rs806368 T/C; p=0.349, Rs1049353 A/G; p=1.00). However, CGI-S, PANSS total, PANSS positive, PANSS negative and PANSS general psychopathology scores were significantly lower in schizophrenia patients with RS6454674 polymorphism than in those not showing polymorphism. Conclusion: Our results suggest that CNR1 gene polymorphisms may be associated with clinical symptoms and disease severity in schizophrenia patientsObjective: The endocannabinoid system contributes to the regulation of emotions, stress, memory, and cognition. It has been reported that endocannabinoids cause GABAergic inhibition and dopaminergic increase in the mesolimbic and nigrostriatal systems, thus playing a part in the neurobiology of schizophrenia. In this study, we investigate cannabinoid receptor 1 (CNR1) gene polymorphisms in schizophrenia patients. Methods: CNR1 gene polymorphisms were studied in 66 schizophrenia patients and 65 healthy controls. To obtain genomic DNA, proteinase K digestion and the salt-chloroform method were used. Clinical Global Impression severity scale (CGI-S) and Positive and Negative Syndrome Scale (PANSS) were administered to evaluate the severity of schizophrenia symptoms. CNR1 gene polymorphism was determined by using polymerase chain reaction (PCR), Restriction Fragment Length Polymorphism (RFLP), and Single Strand Conformation Polymorphism (SSCP) methods for the Rs6454674, Rs806368, and Rs1049353 sites.Results: There was no difference in CNR1 gene polymorphisms between schizophrenia patients and control groups (Rs6454674 T/G; p=0.973, Rs806368 T/C; p=0.349, Rs1049353 A/G; p=1.00). However, CGI-S, PANSS total, PANSS positive, PANSS negative and PANSS general psychopathology scores were significantly lower in schizophrenia patients with RS6454674 polymorphism than in those not showing polymorphism. Conclusion: Our results suggest that CNR1 gene polymorphisms may be associated with clinical symptoms and disease severity in schizophrenia patient

Functional genetic variation of the cannabinoid receptor 1 and cannabis use interact on prefrontal connectivity and related working memory behavior

Cannabinoid signaling is involved in different brain functions and it is mediated by the cannabinoid receptor 1 (CNR1), which is encoded by the CNR1 gene. Previous evidence suggests an association between cognition and cannabis use. The logical interaction between genetically determined cannabinoid signaling and cannabis use has not been determined. Therefore, we investigated whether CNR1 variation predicts CNR1 prefrontal mRNA expression in postmortem prefrontal human tissue. Then, we studied whether functional variation in CNR1 and cannabis exposure interact in modulating prefrontal function and related behavior during working memory processing. Thus, 208 healthy subjects (113 males) were genotyped for the relevant functional SNP and were evaluated for cannabis use by the Cannabis Experience Questionnaire. All individuals performed the 2-back working memory task during functional magnetic resonance imaging. CNR1 rs1406977 was associated with prefrontal mRNA and individuals carrying a G allele had reduced CNR1 prefrontal mRNA levels compared with AA subjects. Moreover, functional connectivity MRI demonstrated that G carriers who were also cannabis users had greater functional connectivity in the left ventrolateral prefrontal cortex and reduced working memory behavioral accuracy during the 2-back task compared with the other groups. Overall, our results indicate that the deleterious effects of cannabis use are more evident on a specific genetic background related to its receptor expression

Paranoid Schizophrenia is Characterized by Increased CB1 Receptor Binding in the Dorsolateral Prefrontal Cortex

A number of studies suggest a dysregulation of the endogenous cannabinoid system in schizophrenia (SCZ). In the present study, we examined cannabinoid CB1 receptor (CB1R) binding and mRNA expression in the dorsolateral prefrontal cortex (DLPFC) (Brodmann's area 46) of SCZ patients and controls, post-mortem. Receptor density was investigated using autoradiography with the CB1R ligand [3H] CP 55 940 and CB1R mRNA expression was measured using quantitative RT-PCR in a cohort of 16 patients with paranoid SCZ, 21 patients with non-paranoid SCZ and 37 controls matched for age, post-mortem interval and pH. All cases were obtained from the University of Sydney Tissue Resource Centre. Results were analyzed using one-way analysis of variance (ANOVA) and post hoc Bonferroni tests and with analysis of covariance (ANCOVA) to control for demographic factors that would potentially influence CB1R expression. There was a main effect of diagnosis on [3H] CP 55 940 binding quantified across all layers of the DLPFC (F(2,71)=3.740, p=0.029). Post hoc tests indicated that this main effect was due to patients with paranoid SCZ having 22% higher levels of CB1R binding compared with the control group. When ANCOVA was employed, this effect was strengthened (F(2,67)=6.048, p=0.004) with paranoid SCZ patients differing significantly from the control (p=0.004) and from the non-paranoid group (p=0.016). In contrast, no significant differences were observed in mRNA expression between the different disease subtypes and the control group. Our findings confirm the existence of a CB1R dysregulation in SCZ and underline the need for further investigation of the role of this receptor particularly in those diagnosed with paranoid SCZ