Stimulation of Gallbladder Emptying and Pancreatic Secretion in Chicks by Soybean Whey Protein 1

Summary Many investigators have studied the effects of trypsin and chymoltrypsin inhibitors on the size, enzyme content and enzyme secretion of the pancreas of rats and chicks. In general, these investigations showed that the pancreases of animals fed diets containing sources of proteolytic inhibitors had greater quantities of enzymes after a fast than comparable fasted animals fed control diets (1-5). When pancreatic enzyme levels were measured after animals were fed, those receiving sources of proteolytic inhibitors generally had lower levels of all pancreatic enzymes than animals not receiving the inhibitor (2-4, 6-8). Thus dietary proteolytic inhibitars appear to cause a general stimulation of the pancreas, resulting in both an increased synthesis and a greater secretion of pancreatic enzymes. Trypsin inhibitors from the soybean (6, 9), the navy bean (10), egg white (5, 9), a synthetic inhibitor, p-aminobenzamidine (11), tannins from carobs (12) or peanut skins (13) and a chymotrypsin inhibitor from potatoes (14) all have been shown to stimulate the pancreas. These are chemically very diverse and have in common only the ability to inhibit proteolysis by interfering with one or more of the pancreatic enzymes. The physiological mechanism whereby these inhibitors stimulate the pancreas is not well understood. Since inhibitors from widely varying sources are able to cause the effects, it appears that the inhibition of proteolysis itself may be the signal to the pancreas rather than some property of the inhibitor molecule per se. Snook (5) has proposed that the gastrointestinal hormone, pancreozymin, mediates the response to trypsin inhibitor. Khayambashi and Lyman (15) showed that a factor present in plasma of rats receiving a diet containing crude trypsin inhibitor stimulated pancreatic enzyme secretion. Rothman and Wells (16) showed that repeated administration of pancreozymin caused pancreatic enlargement and increased enzyme synthesis rats.