The chronically pilocarpine-treated rat in the study of cystic fibrosis: Investigation on submandibular gland and pancreas

Abstract

The chronically pilocarpine-treated rat has been proposed as an animal model for the disease cystic fibrosis, a generalized exocrinopathy. The effect of chronic pilocarpine treatment on structure, composition, and function of the acinar cells of rat submandibular gland and pancreas was investigated by electron microscopy, X-ray microanalysis, and biochemical analysis. The morphological effects of chronic pilocarpine treatment were most pronounced in the pancreas. The number and size of the zymogen granules was increased, and the granules had a less electron-dense appearance. X-ray microanalysis at the cellular level showed in both the submandibular gland and the pancreas a significant increase in calcium and a decrease in sodium. The increase in cellular calcium concentrations can be explained by an increase in the relative volume of secretory material in the cell (assessed by morphometry) and an increase in the local calcium concentration in the secretory material (assessed by X-ray microanalysis at the subcellular level). Chronic pilocarpine treatment caused a disturbance of glycolysis and energy metabolism in the submandibular gland, but no significant effects in this respect were noted in the pancreas. On the other hand, a nearly twofold increase of the pancreatic amylase activity was noted. The pancreas appeared somewhat hyperreactive towards cholinergic stimulation.