Adaptation of Rat Pancreatic Amylase and Chymotrypsinogen to Changes in Diet

Abstract

This study represents an attempt to determine the effect of dietary protein quality and hypophysectomy on the enzymic adaptability of the pancreas in the rat. The specific enzymes studied were amylase, which was purified by immunologic techniques, and chymotrypsinogen (activated), which was isolated by affinity column chromatography. Content and synthesis of each enzyme were accurately determined in relation to total pancreatic protein. When rats were fed a 64% sucrose diet (19% casein), there was a two- to three-fold increase in synthesis of amlyase. However, if a poor-quality protein (gelatin, gluten, or zein) was substituted for casein, there was no increase in the synthesis of amylase in response to increased carbohydrate. When rats were fed a 19% sucrose diet (64% casein), there was a significant increase in chymotrypsinogen synthesis. Of the poor-quality proteins, gluten was the only one effective in stimulating synthesis of chymotrypsinogen. Peptides, either free or as part of a protein, were necessary for the stimulation of chymotrypsinogen synthesis. Amylase synthesis in hypophysectomized rats was considerably depressed and unresponsive to increased carbohydrate. This effect could be partially relieved with hydrocortisone, corticosterone, or thyroxin, but not with growth hormone. Hypophysectomy had little effect on synthesis or content of chymotrypsinogen.