Glucagon-like peptide-1 (GLP-1), one of the gastrointestinal hormones, has various physiological activities, including promoting postprandial insulin secretion, reducing glucagon secretion, inducing satiety, and so on. We previously found that a dietary peptide (protein hydrolysate) prepared from corn zein protein (ZeinH) acutely stimulates GLP-1 secretion in rats and enteroendocrine cells. In another study, we found that continuous feeding of certain low-digestible carbohydrates, such as resistant maltodextrin (RMD) and fructooligosaccharides (FOS), elevates fasting plasma GLP-1 concentrations in rats. In the present study, we investigated whether continuous feeding of RMD and FOS affect ZeinH-induced GLP-1 secretion in rats.
Rats were fed a diet containing 5% cellulose as control, 5% RMD, or 5% FOS for a total of seven weeks. After six weeks of the test period, an intraperitoneal glucose tolerance test (IPGTT) was performed with or without oral administration of ZeinH. After seven weeks of the test period, rats were euthanized, and portal vein plasma and intestinal tissues were collected to measure GLP-1 levels.
In the IPGTT, oral administration of ZeinH lowered glycemic response in all three groups. ZeinH-induced GLP-1 secretion was higher in the RMD group than in the control group. The FOS group had similar GLP-1 responses to the RMD group. GLP-1 concentrations in the intestinal tissues did not differ among the three groups.
These results suggest that continuous feeding of RMD/FOS increases the nutrient-sensing ability of GLP-1-producing cells in the small intestine.
Key Words: low-digestible carbohydrates, GLP-1, resistant maltodextrin, fructooligosaccharides, dietary peptides |
