Pancreatic secretory responses in L-arginine-induced pancreatitis: comparison of diabetic and nondiabetic rats.

Abstract

The aim of this work was to study cholecystokinin-octapeptide (CCK-8)-stimulated pancreatic secretion after the induction of pancreatitis with L-arginine (ARG) in rats with or without streptozotocin (STZ) diabetes. One, 3, 7, and 14 days after pancreatitis induction, rats were surgically prepared with pancreatic duct and femoral vein cannulae under urethane anesthesia. Graded doses of CCK-8 ranging from 9 to 2,400 ng/kg/30 min were administered intravenously. In the control group, the step-wise increasing doses of CCK-8 resulted in a characteristic dose-response curve for the pancreatic volume, protein and amylase secretion (maximal volume, protein and amylase output at 600 ng/kg/30 min of CCK-8: 157 +/- 20.2 microl/30 min, 28.3 +/- 1.18 mg/30 min, and 3,750 +/- 92 IU/30 min, respectively). In rats with pancreatitis, the pancreatic volume (both basal and maximal) and amylase secretion were significantly elevated on day 1 versus the control group; then on days 3,7, and 14, the pancreatic secretory volume and amylase were progressively and significantly decreased versus the control group. However, the protein output was continuously decreased versus the control group on days 1, 3, 7, and 14. In diabetic rats, the maximal volume and protein and amylase output were all significantly decreased versus the control group throughout the experiment. In the diabetes + pancreatitis group, the maximal volume and protein and amylase output were all significantly increased versus the diabetes group on days 1, 3, 7, and 14. These results indicate that in the early phase of ARG-induced pancreatitis, the pancreatic secretion is characterized by increases in secretory volume and amylase, with a simultaneous decrease in protein output. Simultaneous diabetes seems to moderate the CCK-8-stimulated secretory changes in both the early and late phases after ARG-induced pancreatitis.