Effects of reserpine treatment on the ultrastructure of rat parotid and submandibular gland.

The chronically reserpine-treated rat has been used as an animal model for the disease cystic fibrosis, a generalized exocrinopathy. Ultrastructural changes in the parotid and submandibular gland occurring during the seven-day treatment with reserpine were studied by transmission electron microscopy. In the parotid gland, marked changes were observed in the size and structure of the zymogen granules. In fasted control animals, most parotid acinar cells have granules with a virtually homogeneous, electron-dense appearance. During the first three days of treatment, most cells have enlarged, electron-translucent granules. After the third day, and most pronounced at day six and seven, many granules are irregularly electron-dense. In the submandibular gland, reserpine causes a gradual increase in the relative volume of the cell that is occupied by mucus. The ultrastructural changes are discussed in relation to metabolic and biochemical effects of reserpine treatment on salivary glands.