Enhancement of pancreatic secretion by dietary protein in rats with chronic diversion of bile-pancreatic juice from the proximal small intestine.

The regulation of exocrine pancreatic enzyme secretion by dietary protein is known to depend on pancreatic protease activity in the lumen of the proximal small intestine in rats, which is a negative feedback mechanism. We observed whether dietary protein stimulates pancreatic secretion in rats with a 7-day diversion of bile-pancreatic juice (BPJ) from the proximal small intestine under unrestrained and unanesthetized conditions. In the chronically BPJ-diverted rats, hypersecretion of proteases in the fasting state were observed, and pancreatic enzyme secretion was significantly increased after feeding of a 25% casein diet over the hypersecretion in the fasting state. The amplitude of the increments of the secretion after feeding in diverted rats was comparable to that in normal rats. Dietary fat decreased stimulated secretion by the protein diet in the diverted rats, but not in the normal rats. We conclude that there is an upper small intestinal BPJ-independent mechanism for response of pancreatic enzyme secretion to dietary protein, and that dietary fat inhibits pancreatic secretion in diverted rats. The distal small intestine or colon may contribute to the inhibition.