Lower levels of cannabinoid 1 receptor mRNA in female eating disorder patients: Association with wrist cutting as impulsive self-injurious behavior

Abstract

The cannabinoid 1 (CB 1) receptor as the primary mediator of the endocannabinoid (EC) system was found to play a role in eating disorders (EDs), depression, anxiety, and suicidal behavior. The CB 1 receptor is assumed to play a crucial role in the central reward circuitry with impact on body weight and personality traits like novelty-seeking behavior. In a previous study we found higher levels of CB 1 receptor mRNA in patients with anorexia nervosa (AN) and bulimia nervosa (BN) compared to healthy control women (HCW). The aim of the present study was to investigate the possible influence of the EC and the CB 1 receptor system on wrist cutting as self-injurious behavior (SIB) in women with EDs (n=43; AN: n=20; BN: n=23). Nine ED patients with repetitive wrist cutting (AN, n=4; BN, n=5) were compared to 34 ED patients without wrist cutting and 26 HCW. Levels of CB 1 receptor mRNA were determined in peripheral blood samples using quantitative real-time PCR. ED patients with self-injurious wrist cutting exhibited significantly lower CB 1 receptor mRNA levels compared with ED patients without wrist cutting and HCW. No significant differences were found between ED patients without a history of wrist cutting and HCW. Furthermore, a negative association was detected between CB 1 receptor mRNA levels and Beck Depression Inventory (BDI) scores. To our knowledge, this is the first study reporting a down-regulation of CB 1 receptor mRNA in patients with EDs and wrist cutting as SIB. Due to the small sample size, our results should be regarded as preliminary and further studies are warranted to reveal the underlying mechanisms.