BackgroundAltered bile acid (BA) turnover has been suggested to be involved in the improved glucose regulation after Roux-en-Y gastric bypass (RYGB), possibly via stimulation of GLP-1 secretion. We investigated the role of exogenous as well as endogenous BAs for GLP-1 secretion after RYGB by administering chenodeoxycholic acid (CDCA) and the BA sequestrant colesevelam (COL) both in the presence and the absence of a meal stimulus.MethodsTwo single-blinded randomized cross-over studies were performed. In study 1, eight RYGB operated participants ingested 200 ml water with 1) CDCA 1.25 g or 2) CDCA 1.25 g + colesevelam 3.75 g on separate days. In study 2, twelve RYGB participants ingested on separate days a mixed meal with addition of 1) CDCA 1.25 g, 2) COL 3.75 g or 3) COL 3.75 g × 2, or 4) no additions.ResultsIn study 1, oral intake of CDCA increased circulating BAs, GLP-1, C-peptide, glucagon, and neurotensin. Addition of colesevelam reduced all responses. In study 2, addition of CDCA enhanced meal-induced increases in plasma GLP-1, glucagon and FGF-19 and lowered plasma glucose and C-peptide concentrations, while adding colesevelam lowered circulating BAs but did not affect meal-induced changes in plasma glucose or measured gastrointestinal hormones.ConclusionIn RYGB-operated persons, exogenous CDCA enhanced meal-stimulated GLP-1 and glucagon secretion but not insulin secretion, while the BA sequestrant colesevelam decreased CDCA-stimulated GLP-1 secretion but did not affect meal-stimulated GLP-1, C-peptide or glucagon secretion, or glucose tolerance. These findings suggest a limited role for endogenous bile acids in the acute regulation of postprandial gut hormone secretion or glucose metabolism after RYGB.

Enhanced glucagon-like peptide-1 (GLP-1) secretion is important for improved glycemic control after Roux-en-Y gastric bypass (RYGB) and higher concentrations of circulating bile acids (BA) have been suggested to be involved. The BA chenodeoxycholic acid (CDCA) stimulates GLP-1 secretion after RYGB in the absence of nutrients. In this study we investigated the effects of oral intake of CDCA or the BA sequestrant colesevelam (COL) on postprandial GLP-1 secretion in RYGB operated subjects. We hypothesized that CDCA would increase secretion and that COL would decrease secretion by reducing re-absorption of endogenous BA. Twelve participants (BMI 31±2 (mean±SEM) kg/m2, age 43±3 years, time from RYGB 4.3±0.5 years, weight loss after RYGB 34±5 kg) were studied in a single-blinded, randomised study with four experimental days: 1) A mixed meal consisting of solid/semisolid components (1523 kJ, 53E% carb, 33E% fat, 14E% prot) 2) Mixed meal added 1250 mg CDCA 3) Mixed meal added COL 3750 mg 4) Mixed meal with COL administered both as 3750 mg tablets the evening before the experiment and as 3750 mg added to the meal. Oral intake of CDCA increased GLP-1 significantly compared with mixed meal alone (p=0.03), whereas neither single (p=0.74) nor double (p=0.28) dosage of COL affected GLP-1 secretion (Incremental AUC (iAUC) GLP-1: Meal: 2792±288 pmol x min, CDCA: 4362±618, COL: 2703±330, COLx2: 3328±380). Plasma glucose and C-peptide (iAUC) decreased after CDCA but both were unchanged after COL administration vs. meal alone. Beta-cell function (AUC C-peptide/AUC plasma glucose) was equal between all study days. In summary, administration of the exogenous BA CDCA potentiated mixed-meal stimulated GLP-1 secretion after RYGB but did not affect beta-cell function. Administration of the BA sequestrant COL did not affect GLP-1 secretion, glucose concentrations or beta-cell function, suggesting a limited role for endogenous BA for regulation of postprandial glucose metabolism after RYGB. Disclosure M.S. Svane: None. I. Jonsson: None. V. Kristiansen: None. R.E. Kuhre: None. N.J. Wewer Albrechtsen: Research Support; Self; Mercodia, Novo Nordisk A/S. Speaker's Bureau; Self; Merck Sharp & Dohme Corp. J.J. Holst: Advisory Panel; Self; Novo Nordisk A/S. S. Madsbad: None. K.N. Bojsen-Moller: None. Funding European Research Council (695069)