Weight loss by calorie-restriction does not alter appetite-regulating gut hormone responses from perfused rat small intestine.

Postprandial secretion of the appetite-inhibiting hormones, glucagon-like peptide-1 (GLP-1) and peptide YY, are reduced with obesity. It is unclear if the reduced secretion persists following weight loss (WL), if other appetite-inhibiting hormones are also reduced, and if so whether reduced secretion results from intrinsic changes in the gut. To address whether WL may restore secretion of GLP-1 and other appetite inhibiting hormones, we performed a gut perfusion study of the small intestine in diet-induced obese (DIO) rats after WL. A 20% weight loss (means±SEM (g): 916±53 vs. 703±35, P<0.01, n=7) was induced by calorie restriction, and maintained stable for ≥7 days prior to gut perfusion to allow for complete renewal of enteroendocrine cells. Age-matched DIO rats were used as comparator. Several gut hormones were analysed from the venous effluent and gene expression was performed on gut tissue along the entire length of the intestine. Secretion of cholecystokinin, gastrin, glucose-dependent insulinotropic peptide, GLP-1, neurotensin, and somatostatin was not affected by WL during basal conditions (P≥0.25) or in response to macronutrients and bile acids (P≥0.14). Glucose absorption was indistinguishable following WL. The expression of genes encoding the studied peptides, macronutrient transporters (glucose, fructose, and di-/tri-peptides) and bile acid receptors did also not differ between DIO and WL groups. These data suggest that the attenuated postprandial responses of GLP-1, as well as reduced responses of other appetite inhibiting gut hormones, in people living with obesity may persist after weight loss and may contribute to their susceptibility for weight regain.