EFFETTO DELLA VELOCITÀ DI ASSUNZIONE DI CIBO E DELLA PALATABILITA¿ SULLA SECREZIONE DI PEPTIDI GASTROINTESTINALI NELL¿ OBESITA¿ SEMPLICE E GENETICA.

Abstract

Anorexigenic gastrointestinal hormones as peptide YY (PYY), glucagon-like peptide 1 (GLP-1) and orexigenic hormone ghrelin influence the activity of the arcuate nucleus (ARC) neurons in the hypothalamous. The ARC plays a crucial role in the regulation of food intake and energy homeostasis. In contrast, the mesolimbic dopamine system encodes subjective ‘liking’ and ‘wanting’ of palatable foods, which is subjected to modulation by the hindbrain and the hypothalamic homeostatic circuits and by satiety and adiposity hormones. Reportedly, obesity reflects an energy imbalance in which genetically susceptible individuals become increasingly vulnerable to an ‘obesogenic’ environment. Dietary and behavioral approaches to severe obesity are frequently associated with limited persistent success over the time rendering bariatric surgery one of the more promising therapy for “super-obese” patients. Laparoscopic sleeve gastrectomy (LSG) is a purely “restrictive” operation applied in patients with body mass index (BMI) <50 kg/m2. Although early enthusiastic results on weight loss after LSG have been published, the underlying mechanism(s) of weight loss is still unknown and it could involve pos-LSG alterations of gastrointestinal hormones. Nowadays the number of overweight and obese people in the world are roughly 2 billion in 2013. The lifestyle of the modern civilization facilitates diffusion of fast feeding and, consequently, high energy intake. At the same time hedonic hunger may powerfully stimulate food intake in an environment where highly palatable foods are omnipresent and contribute to the diffusion of overweight and obesity. Therefore, understanding the physiological mechanisms underlying these eating behaviors may help to contrast it. The anorexigenic action of PYY is preserved in obese patients, although the circulating level of the peptide is low during fast and postprandial phase. obese individuals actually display low circulating ghrelin levels that could suggest greater sensitivity to the hormone. A pathogenic role for ghrelin has been suggested in individuals with genomic obesity as Prader–Willi syndrome, where hyperghrelinism precedes the development of obesity. On the contrary, only few studies have investigated postprandial GLP-1 and PYY in PWS, besides reporting conflicting results. Since the critical rule of gastrointestinal hormones in homeostatic and hedonic regulation of food intake and in the physiophatology of obesity we decided to study dynamically their secretion in association with eating behavior involved with the development of obesity. Particularly we conducted three studies: Study 1: evaluation of post-prandial anorexigenic gut peptide, appetite and glucometabolic responses at different eating rates in obese patients undergoing laparoscopic sleeve gastrectomy. Aim of this study was to determine whether eating the same meal at different rates (fast vs. slow feeding) evokes different post-prandial anorexigenic gut peptide responses in ten obese patients undergoing LSG. Circulating levels…