Role of the Adrenals in the Development of Streptozotocin (STR)-Induced Diabetes in Male Albino Rats

Abstract

Diabetes induced by streptozotocin (STR) (55 mg/kg i.v.) in non-fasting, male albino rats is considerably mitigated by adrenalectomy. The timing of the operation is important for the effect of blood glucose. The later the adrenalectomy, the lesser the protection against STR. Plasma insulin in intact, STR-treated rats is significantly lower than in rats that have also been adrenalectomized. Pancreatic insulin in both groups is 10 times lower than in normal controls and adrenalectomized rats. Plasma FFA are distinctly elevated in intact, STR-treated rats. Adrenalectomy in these diabetic animals reduces plasma FFA to levels below those of normal controls. The changes in the glycogen contents of the diaphragm and myocardium of STR-treated rats are reversed by adrenalectomy. The rate of pancreatic insulin degradation might be retarded or the rate of secretion increased. In addition, sensitivity to insulin is exaggerated after adrenalectomy, as is evident from the changes in blood sugar and the glycogen contents of the organs. These changes in the effects of insulin are ascribed to deprivation of adrenal steroids and in particular glucocorticoids. Loss of the adrenal medulla is presumably one of the causes of the changes in plasma FFA.