Effect of Hyperglycemia and Hypoglycemia on the Glycogen Content of the Pituitary and Adrenal Glands of Normal, Subdiabetic and Diabetic Rats

The glycogen content of pituitary, adrenal and thyroid tissue of alloxandiabetic and normal rats was determined. An increased glycogen content was found in these endocrine glands in the diabetic rats. The pituitary glycogen content appeared to reflect the blood sugar level. When the blood sugar of normal, subdiabetic and diabetic rats was elevated by massive injections of glucose, the pituitary glycogen content was increased moderately. When the blood sugar of diabetic rats was lowered by insulin injection, the pituitary glycogen content decreased; however, this change in glycogen content often lagged behind the blood sugar changes. By contrast, the adrenal glycogen content did not reflect the blood sugar level; when the blood sugar was decreased by insulin treatment (in the diabetic rat) or elevated by glucose administration (in both normal and diabetic rats), the adrenal glycogen content was decreased. The possible mechanisms by which hyper- and hypoglycemia affect the glycogen content of the endocrine glands are discussed.