Plasma Concentrations of GLP-1 and PYY in Rats Fed Dietary Fiber Depend on the Fermentability of Dietary Fiber and Respond to an Altered Diet

Background: It was reported to be associated with intake of dietary fiber and gut hormone. We compared the effect of dietary fiber on the plasma concentration of glucagon-like peptide-1 (GLP-1) and peptide YY (PYY). Methods: Firstly, male Wistar rats (10 wk old) were fed a fiber-free diet (FF diet, AIN-93G-based diet without cellulose) or one of nine FF diets with 5% dietary fiber for 21 days. Cellulose, guar gam (GG), partially hydrolyzed guar gum (PHGG), sugar beet fiber (BF), konjac mannnan (KM), raffinose (RF), hydroxypropyl starch (HPS), hydroxypropyl distarch phosphate (HPDP) and Akamoku (AK) were used as dietary fiber sources. Secondly, we then determined whether the concentrations of GLP-1 and PYY in portal and aorta plasma and microbiota in cecal contents responded to an altered diet. Male Wistar rats (10 wk old) were fed the PHGG diet for 20 days before being changed to the FF diet. Results: The amount of short chain fatty acids (SCFA) in the cecal contents markedly increased in rats fed the GG, PHGG, BF, KM, RF, HPS or HPDP diets compared with SCFA in rats fed the FF, CL or AK diets. The concentrations of GLP-1 and PYY in portal plasma positively correlated with the concentration of SCFA in the cecal contents and cecal tissue weight. The concentrations of GLP-1 and PYY, in the altered diet group decreased to the same concentration as that measured in the FF group. However, it was low the similarities in the cecal bacteria population. Conclusion: The plasma concentrations of GLP-1 and PYY increased with increasing the amounts of SCFA, the products of DF fermentation, in the cecal contents. GLP-1 and PYY plasma concentrations and SCFA concentrations in the cecal contents rapidly responded to the altered diet, but the cecal bacteria population did not.