Altered glycogen metabolism in the submandibular and parotid salivary glands of rats with streptozotocin-induced diabetes.

Experimental animal models of diabetes induced either by alloxan or streptozotocin have been used to study aspects of the pathophysiology of this disease. The purpose of this study was to examine the metabolism of glycogen in the submandibular and parotid salivary glands of diabetic rats. Diabetes was induced by an intraperitoneal injection of streptozotocin. Eight weeks after the induction of diabetes, the animals were sacrificed and the submandibular and parotid salivary glands were removed. The glands were analyzed for glycogen concentration, and activities of glycogen synthase and phosphorylase. Although the diabetic rats consumed more food than controls, they had a lower body weight eight weeks after diabetes induction. Glycogen concentration in the submandibular and parotid glands increased by about 27% and 130%, respectively. Glycogen phosphorylase a in the submandibular gland of diabetic rats showed a reduction of between 75% and 68% compared with controls. In parotid glands, phosphorylase a was reduced by between 84% and 79% compared with controls. The increase in the activity of glycogen synthase a (active) varied from 64% to 130% for the submandibular glands and from 75% to 110% for the parotid compared with controls. These results suggest that the diabetic state influences glycogen metabolism in the submandibular and parotid salivary glands of rats.