Elevation of plasma peptide YY and pancreatic juice hypersecretion following massive small bowel resection in the rat

To clarify a physiological role of endogenous peptide YY(PYY) on pancreatic exocrine secretion, gastrointestinal transit and bile flow, a hyper-PYY-emia model was constructed by performing a massive small bowel resection using rats. (1) 75% resection of the small intestine was performed at its distal side. Two weeks after surgery, these rats were fed a liquid meal, and intestinal transit of contents was observed and plasma PYY and secretin concentrations were measured by radioimmunoassay. (2) Two weeks after the same surgery, a liquid meal was infused into the duodenum, and both pancreatic juice and bile were collected separately under general anesthesia. Transit of the intestinal contents from the pyloric ring, plasma CCK concentrations, pancreatic juice flow, amylase output, and bile flow were determined. Hyper-PYY-emia occurred following surgery both at fasting and after feeding, accompanied by retardation of gastrointestinal transit, increase of pancreatic juice flow and decrease of bile flow. Plasma secretin levels were elevated slightly, while CCK levels remained unchanged. In conclusion, massive small bowel resection is a useful model to induce hyper-PYY-emia in rats. It is considered that, in a malnutritional state after small intestinal resection, a colonic regulatory mechanism, via humoral factors such as PYY, participates in the feedback regulation of proximal intestinal as well as of pancreatic function.