Pancreatic secretion of lysosomal enzymes stimulated by intraduodenal instillation of a liquid meal in rabbits

Studies have been performed to determine the effect of intraduodenal food on pancreatic secretion of lysosomal enzymes. Intraduodenal instillation of a liquid meal (3 g/kg body weight; 15.3% protein, 19.7% fat, 59.7% carbohydrate) caused significant increases in pancreatic juice volume and pancreatic secretion of amylase and protein compared with basal values for 2 h after instillation in anaesthetized rabbits. Intraduodenal instillation of a liquid meal also caused significant increases in pancreatic secretion of three lysosomal enzymes (cathepsin B, N-β-acetylgalactosaminidase and N-acetyl-β-glucosaminidase) compared with basal values for 2 h after instillation. In addition, there were significant correlations between cathepsin B secretion and amylase secretion (r = 0.7764, P < 0.001) and between cathepsin B secretion and protein secretion (r = 0.6216, P < 0.001), both in basal conditions and in response to the liquid meal. These results are evidence for the localization of lysosomal enzymes in the secretory granules-zymogen granules in normal acinar cells, and also indicate that the pancreatic secretion of lysosomal enzymes is gut-hormone-regulated.