EFFECTS OF RESERPINE ON THE ULTRASTRUCTURE AND SECRETORY RESPONSES OF RAT EXOCRINE PANCREAS

The effects of chronic reserpine administration on rats mimic in several respects the exocrine dysfunction observed in cystic fibrosis. This drug treatment has been proposed as a model for the human disease. In cystic fibrosis, the pancreas is usually a major organ involved pathologically. The present study was designed to investigate the fine-structural morphology and secretory responses of the pancreas of rats treated chronically with reserpine. Reserpine treatment resulted in increased storage of zymogen granules in pancreatic acinar cells and an apparently reduced ability to discharge these granules following stimulation with cholecystokinin. In addition, granule storage may have produced feedback inhibition on the protein synthesizing machinery as manifested by a slight reduction of rough endoplasmic reticulum. Many acinar cells also had autophagic bodies, suggesting the degradation of excess secretory material. Cholecystokinin stimulation of both control and reserpine-treated rats resulted in the appearance of large vacuoles containing myelin figures and granular material, numerous autophagic bodies (cytosegresomes), and a slight decrease of rough endoplasmic reticulum in pancreatic acinar cells. Secretin stimulation did not cause large vacuole formation, but did cause cytosegresome formation in acinar cells. Large vacuoles in intralobular ducts were noted after reserpine treatment, but were also present after stimulation of untreated pancreas with cholecystokinin. © 1979.