Insulin therapy prevents spontaneous recovery from streptozotocin-induced diabetes in Syrian hamsters. An autoradiographic and immunohistochemical study.

Streptozotocin (Sz) given as a single dose of 50 mg/kg body wt. caused severe diabetes in Syrian hamsters. However, the level of blood glucose decreased gradually after 21 days post-Sz and reached the near normal level at 70 days in 90% of hamsters. The recovery from diabetes was associated with the regeneration of the beta-cells of islets and a reduction in the initially increased number of alpha- and delta-cells. Daily treatment of diabetic hamsters with insulin was associated with the persistence of severe diabetes, lack of or minimal tendency for beta-cell regeneration and sustained hyperplasia of alpha- and delta-cells in 90% of hamsters. Insulin also inhibited DNA synthesis (as measured by incorporation of tritiated thymidine), in ductal, ductular and acinar cells in Sz-pretreated hamsters but not in normoglycemic control hamsters treated with insulin alone. The results demonstrate a deleterious effect of exogenous insulin in the course of Sz-induced diabetes in hamsters.