Amylase secretion by rat pancreas following prolonged stimulation by unheated soybean flour.

Abstract

Rats were fed diets containing either heated or unheated soybean flour for 3 months. Relative to body weight the pancreatic glands of rats fed the unheated soybean flour diet secreted the same volume but less protein and amylase, both in basal fasted state and following stimulation with pancreozymin. Administration of a test meal of unheated soybean flour, presumably stimulating secretion of pancreozymin, caused a smaller percentage reduction of amylase content in pancreases of rats chronically fed unheated soybean flour than in those subsisting on heated soybean flour diet. Pieces of pancreas derived from both groups of rats were incubated in the presence of two doses of pancreozymin. Pancreatic glands of both groups secreted similar amounts of amylase when stimulated by a low dose of pancreozymin. Pancreases of rats fed heated soybean flour, but not those of rats subsisting on unheated soybean flour, responded to a larger dose of pancreozymin with increased release of amylase. The results are interpreted as a manifestation of an increased activity of pancreozymin inactivating enzyme in body fluids of rats fed unheated soybean flour. However, fatigue of the pancreatic exocrine secretion apparatus resulting from prolonged stimulation by the heat-labile soybean trypsin inhibitors cannot be excluded.