Immunohisto- and cytochemical studies of pancreatic enzymes in peri-insular and tele-insular acinar cells of streptozotocin-induced diabetic rats.

Previous studies have demonstrated that the exocrine pancreatic tissue is influenced by islet hormones and that under diabetic condition, amylase secretion is altered. On the other hand according to the topographical location of the acini with reference to the islet of Langerhans, the exocrine parenchyma has been partitioned into peri- and tele-insular regions. In the present study, we have analyzed by immunofluorescence and protein A-gold immunocytochemistry the distribution of two enzymes, amylase and chymotrypsinogen, on pancreatic tissues of short- and long-term diabetic rats. The alteration in amylase secretion occurring under diabetic condition was found to follow the topographical partition of the pancreas. Acinar cells, located in the peri-insular regions of the pancreas (close to the islets of Langerhans), appeared totally devoid of amylase immunolabeling while positive and negative cells were found in the tele-insular regions (at a distance from the islets). In addition, quantitation of amylase immunolabeling present in positive cells has demonstrated that although amylase is still secreted by these cells, its processing is altered. Since the partition of the exocrine parenchyma is due to the paracrine influence of islet hormones, the data obtained demonstrate and reinforce the fact that the endocrine and exocrine components of the pancreas are functionally interrelated in normal as well as in pathological conditions.