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.

CRP reduction following gastric bypass surgery is most pronounced in insulin-sensitive subjects.

OBJECTIVE: Obesity is frequently associated with insulin resistance, dyslipidemia, hypertension and an increased risk of cardiovascular disease, reflected in elevated markers of inflammation, in particular C-reactive protein (CRP). To what extent the insulin resistance or the obesity per se contributes to increased CRP levels is unclear. In morbidly obese patients, gastric bypass surgery causes marked changes in body weight and improves metabolism, thereby providing informative material for studies on the regulation of inflammatory markers. DESIGN: Prospective, surgical intervention study of inflammatory markers in morbidly obese subjects. SUBJECTS: In total, 66 obese subjects with mean age 39 y and mean body mass index (BMI) 45 kg/m2 were studied prior to and 6 and 12 months following Roux-en-Y gastric bypass (RYGBP) surgery. MEASUREMENTS: Serum concentrations of high sensitivity CRP, serum amyloid A (SAA) and interleukin-6 (IL-6), as well as markers of glucose and lipid metabolism. RESULTS: Prior to surgery, CRP levels were elevated compared to the reference range of healthy, normal-weight subjects. CRP correlated with insulin sensitivity, as reflected by the homeostatic model assessment (HOMA) index, but not BMI, when corrected for age and gender. Surgery reduced BMI from 45 to 31 kg/m2 and lowered CRP, SAA and IL-6 levels by 82, 57 and 50%, respectively, at 12 months. The reduction in CRP was inversely related to HOMA at baseline independently of the change in body weight (r=-0.36, P=0.005). At 12 months, 140 and 40% reductions in CRP were seen in subjects with HOMA < 4 (insulin sensitive) and HOMA>9 (insulin resistant) despite similar reductions in BMI. Reductions in SAA and IL-6 tended to parallel the changes in CRP, but were less informative. CONCLUSION: In morbidly obese subjects, gastric bypass surgery lowers energy intake, reduces inflammatory markers and improves insulin sensitivity. Despite a marked reduction in body weight, only a small effect on CRP levels was seen in insulin-resistant patients, indicating that flexibility of circulating CRP levels is primarily dependent upon insulin sensitivity rather than energy supply.