Endocrine cells in the rat pancreatic and bile duct system: alteration in diabetes.

Endocrine cells of the pancreatic and bile duct system of the diabetic rat were characterized with reference to their influence on duct function. In streptozotocin-induced diabetic rats, the endocrine cells showed various changes in number and topographic distribution along the epithelial lining of the duct system. With the exception of insulin cells, which demonstrated a marked decrease, the number of duct endocrine cells generally increased in the duct system of the diabetic animal, particularly in the terminal portion of both the common hepatic and the accessory pancreatic ducts encompassed by the muscle sphincters. Among them, the cells secreting somatostatin, a potential peptide inducing contraction of the muscle sphincter, showed a remarkable increase in the opening portion of the common hepatic and the accessory pancreatic ducts of the diabetic animal. The duct cells producing glucagon and pancreatic polypeptide, the hormones exerting an inhibitory effect on exocrine secretion of duct and acinar cells, also increased significantly in the duct system of the diabetic animal. These results suggest that the duct endocrine cells are closely related, not only to functional properties of the duct system, but also to disorders of the pancreas and biliary tract in diabetes.