Background: Accumulating data confirmed that the endocannabinoid system (ECS) is involved in the regulation of stress response and emotional processes, therefore ECS became an important pharmacological target as a potential anxiolytic. Although unequivocal data from animal studies confirmed the relevancy of the ECS in anxious phenotype, human genetic data are poorly available in the literature in this field. In the presented studies we tested possible associations between anxious phenotype and the cannabinoid receptor 1 and the fatty acid amide hydrolase gene polymorphisms.
Methods: Almost 900 subjects were involved in our study from the general population. Anxious phenotype was measured by the State-Trait Anxiety Inventory (STAI) and the anxious subscale of the Brief Symptom Inventory (BSI-ANX). Genetic polymorphisms were genotyped from buccal mucosa samples' DNA by MassArray Sequenom technic. General linear models and post hoc tests were performed for statistical analyses.
Results: Phenotypic variances were not dependent on single marker's effect. However, interaction analyses provided significant results. Carriers of GG genotype of the rs2180619 scored significantly higher on the STAI-T scale in presence of SS genotype of 5-HTTLPR compared to other allelic variants (p=0.0006). SS genotype together with GG genotype meant almost a 5-fold risk to be anxious (OR=4.64, 95% CI: 1.7-12.71). In case of the C385A polymorphism of FAAH gene, A allele was associated with high scores of the BSI-ANX and the STAI-T if there were multiple childhood traumas in the anamnesis compared to C allele (pinteract=0.00002; pinteract=0.0023; respectively).
Conclusion: Our results confirmed earlier positive data on the association between ECS and anxious phenotype. According to our findings ECS plays a significant role in the pathomechanism of anxious disorders by a complex mechanism of genetic interaction with the serotonin transporter gene and childhood traumas.