Lack of response to dietary protein in pancreatic secretion by chronic deprivation of jejunal chyme in rats

Background: Exocrine pancreatic secretion is regulated by luminal factors, bile-pancreatic juice (BPJ), and food chyme. The effects of 10 days' chronic deprivation of luminal chyme on the stimulation of exocrine pancreatic secretion by dietary protein were examined in rats with or without BPJ in the jejunum. Methods: The jejunum was deprived of ingested food by preparing a whole-jejunum blind loop. The BPJ was diverted by a common bile-pancreatic duct catheter and was returned to the upper jejunum (with BPJ) or ileum (without BPJ). Results and Conclusion: In rats with the ingested food and BPJ in the jejunum (control), secretion rates in terms of volume, protein, amylase, and trypsin increased more than twofold from the rates in the fasting state after a jejunal injection of peptic hydrolysate of casein. In contrast, the secretions were not increased by the protein injection in the rats deprived of jejunal chyme with or without BPJ in the jejunum. Even in the chyme-deprived group the protein and trypsin secretion of the fasting state was significantly higher in BPJ-diverted rats than in rats with BPJ. These results showed that chronic deprivation of the jejunal chyme impaired responses of the exocrine pancreas to dietary protein but not the hypersecretions of the pancreas by BPJ diversion.