GLP-1 Secretion Induced by Dietary Proteins and Peptides, and Its Hypoglycemic and Thermic Effects

Abstract

Secretion of the gastrointestinal hormone glucagon-like peptide-1 (GLP-1) primarily increases after meals, exerting various physiological functions, including alleviation of postprandial hyperglycemia through promotion of insulin secretion. In animal studies we have demonstrated that various dietary proteins and peptides are able to lower glycemic responses through promotion of GLP-1 secretion. Furthermore, through the use of a GLP-1-producing cell line and a dipeptide library, we have discovered 11 new active peptides, the sequence Trp-Tyr being particularly potent for stimulating GLP-1 secretion. Dietary protein intake strongly induces postprandial thermogenesis. In rats and mice, the increase of rectal temperature (core body temperature) after oral protein administration was abolished by inhibition or knockout of the GLP-1 receptor. These findings suggest a novel physiological role for GLP-1 in the induction of postprandial thermogenesis by dietary protein. In this review, we focus on the GLP-1 secretion-promoting effects of dietary peptides, and introduce a newly discovered physiological function of GLP-1.