Bariatric surgery and the central nervous system.

Bariatric procedures are now known to have an effect on hunger as well as on metabolism. The role of central nervous pathways in causing these effects after bariatric surgery is now being elucidated. A brief overview of these pathways has been presented for the sake of bariatric surgeons. A PubMed search was made using various search phrases to retrieve all original articles concerning the effect of bariatric surgery on the neural pathways. The mechanisms regulating the food intake and energy expenditure can be broadly divided into homeostatic and hedonic systems. The effect of bariatric surgery on the homeostatic system in animal models is not clear. A decrease in preference for sweet taste and high calorie foods has been demonstrated in animal models. The effect of bariatric surgery on the hedonic system in humans has been consistent with decreased activation of the hedonic system being demonstrated by functional MRI and decreased preference for intake of high energy foods also being observed post-surgery. The effect of bariatric surgery on dopamine signaling, which is involved in the hedonic system, is however not clear. Functional MRI studies have also demonstrated increased activation of the hypothalamus after surgery. Various studies utilizing questionnaires have demonstrated increased satiety and decreased hunger after bariatric surgery.