Effects of non-homeostatic feeding circuits on the long term efficacy of bariatric surgery

Bariatric surgery is an effective surgical option for treating severe obesity resistant to dieting and exercise. Bariatric surgeries have been shown to adjust the metabolic profile and structure of the patient, typically addressing the underlying issue contributing to the patient's obesity. However, some patients do not experience this efficacy, suggesting another, non-metabolic,etiology for their obesity. In order to provide adequate treatment for obesity, the non-metabolic mechanisms of feeding behavior, and their dysfunction, must be understood. The current study investigates single nucleotide polymorphisms (SNPs) in the dopamine and endocannabinoid brain pathways, responsible for reward and regulatory functions, respectively. These SNPs had been previously associated with drug addiction. It was predicted that the allelic frequency of the mutant genotypes for each SNP, rs324420 (endocannabinoid-related) and rs1076560 (dopamine-related), would be elevated in the bariatric population compared to the general population. SNP analysis was conducted using allele-specific polymerase chain reaction and quantitative real-time polymerase chain reaction. For both polymorphisms, the allelic frequency of the mutant allele was elevated in the bariatric population compared to the general population. The observed increase in mutant allelic frequency was much greater for rs324420 than for rs1076560. These results suggest that similar neuropathology may be at play in the manifestation of disordered eating as is in the etiology of substance use disorders. Future research should compare SNP analyses of populations with binge-eating disorder and populations with food addiction.