Postprandial changes in gut regulatory peptides in gastric bypass patients

Objective: The marked weight loss induced by Roux-en-Y gastric bypass (RYGBP) for morbid obesity is still incompletely understood. It has been suggested that, besides the restriction imposed by the surgical procedure, alterations in gut regulatory peptides signaling the brain might contribute. The aim of this study was to measure the putative satiety peptides peptide YY (PYY), glucagon-like peptide-1 (GLP-1), pancreatic polypeptide (PP) and pro-neurotensin (pro-NT) in response to fasting and feeding. Design: The study is a cross-sectional study. After a prolonged overnight 14 h fast, a standardized mixed meal (574 kcal) was provided. Blood samples for peptide measurements were obtained before and after the meal. Subjects: Forty subjects (20 males and females) were included; 10 morbidly obese; (mean age 41 +/- 7 years; mean BMI 44 +/- 3 kg/m(2)), 10 operated with RYGBP (age 45 +/- 5 years; BMI 35 +/- 6 kg/m(2)), 10 aged-matched lean (age 44 +/- 5 years; BMI 24 +/- 3 kg/m(2)) and 10 young lean subjects (age 26 +/- 2 years; BMI 23 +/- 2 kg/m(2)). Measurements: Plasma concentrations of PYY, GLP-1, PP and pro-NT were obtained. Results: PYY levels increased more in the RYGBP group than in the other groups after the test meal. GLP-1 levels rose in the RYGBP patients, with a small increase seen in the age-matched lean group. PP concentrations increased similarly in all groups postprandially. Pro-NT levels were highest in surgical patients, with no meal effect. Conclusion: RYGBP subjects displayed exaggerated PYY and GLP-1 responses to a standardized meal and demonstrated higher pro-NT levels both pre- and postprandially. The findings indicate that possibly the alterations in gut peptide secretion may promote weight loss after gastric bypass surgery.