Resistant Protein Promotes Glucagon-like Peptide-1 Secretion by Controlling the Cecal Fermentation in Rats Fed High Amylose Corn Starch

Ryoko Shimada,Junichi Matsumoto,Kiyoshi Ebihara,Mikiharu Doi

doi:10.11648/j.jfns.20190706.11

Abstract

It was examined whether undigested protein, namely resistant protein, affects glucagon-like peptide-1 (GLP-1) secretion in rats fed high amylose corn starch (HACS). Rats were fed one of three experimental diets for 28 d: casein without HACS, casein with HACS or dashigara with HACS. Dashigara is produced from Katsuobushi (smoke-dried skipjack tuna) treated with microbial protease. The apparent digestibilities of casein and dashigara are 96.0% and 84.5%, respectively. The amount of rat cecal butyric acid and propionic acid were as follows: the dashigara with HACS group > the casein with HACS group > the casein without HACS group. The dashigara with HACS group had significantly greater cecal butyric acid and lower cecal succinic acid than the casein with HACS group. The GLP-1 concentration in portal vein blood increased as the amount of butyric acid and propionic acid in the cecal contents increased. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments showed that the composition of cecal microbiota differed among the three groups. These results suggest that resistant protein contained in dashigara promotes GLP-1 secretion by controlling fermentation efficiency as well as the fermentation profile of HACS through the changes in cecal microbiota in rats fed HACS.

Highlights

Katsuobushi is an essential ingredient in Japanese cuisine
The glucagon-like peptide-1 (GLP-1) concentration in portal vein blood was significantly higher in the casein+high amylose corn starch (HACS) group compared with the casein group, and the concentration was significantly lower in the casein+HACS group compared with the dashigara+HACS group (Table 4)
The GLP-1 concentration in portal vein blood significantly correlated with the amount of total short-chain fatty acids (SCFA) (r=0.999, P=0.002) and propionic acid (r=0.995, P=0.023) in the cecal contents

Summary

Introduction

Katsuobushi is an essential ingredient in Japanese cuisine. It is processed by boiling slivered skipjack tuna, removing the bones and skins, smoking and drying the muscle parts, and applying a fine mold to the surface. The most fundamental use of Katsuobushi is in dashi stock which forms the basis of many Japanese soups and sauces. Dashi is prepared using a more traditional method of heating flakes of Katsuobushi in near-boiling water, and straining off the liquid. Dashi-no-moto is obtained by digesting Katsuobushi flakes with endoand exo-type microbial proteases. Katsuobushi flakes change to grounds called “dashigara” in which the taste components are lost. Dashigara contains protein that resists protease digestion, and is known as resistant protein

Objectives

Methods

Results

Discussion

Conclusion