Immunocytochemical studies of pancreatic acinar cells from spontaneously diabetic BB Wistar rats

Amylase in pancreatic tissue from normal and spontaneously diabetic BB Wistar rats was assessed by immunocytochemistry and analyzed by biochemical approach. Amylase immunofluorescence, in pancreatic tissues from control "non-BB" Wistar rats, gave a positive reaction. By electron microscopy, it was detected in the rough endoplasmic reticulum, Golgi apparatus, immature, and mature secretory zymogen granules of the acinar cells. Quantitative evaluations of the intensity of labeling have demonstrated the presence of an increasing gradient which followed precisely the secretory pathway. In the spontaneously diabetic BB Wistar rats, concomitant with the disappearance of insulin containing cells in the islets of Langerhans, no reaction for amylase was found in the acinar cells. Labeling for amylase was markedly reduced in the cellular organelles and the gradient along the secretory pathway was altered. In insulin-treated diabetic rats, labeling for amylase was restored. These results were in agreement with those obtained by the biochemical approach and demonstrated that, in diabetic conditions, secretion of amylase by pancreatic acinar cells is selectively impaired. This alteration, found also in pancreatic tissue from streptozotocin-diabetic rats, demonstrates that the exocrine parenchyma is under the influence of islet hormones and that both the pancreatic exocrine and endocrine tissues are closely related forming an integrated organ.