EFFECT OF STREPTOZOTOCIN-INDUCED DIABETES AND ISLET TRANSPLANTATION IN PROXIMAL SKELETAL-MUSCLE - A HISTOCHEMICAL AND MORPHOMETRIC ANALYSIS

The effect of pancreatic islet transplantation on the development of d iabetic myopathy in streptozotocin-induced diabetic Lewis rats was exa mined histochemically and morphometrically in a proximal striated (rec tus femoris) muscle. Diabetes was induced by streptozotocin administra tion, and diabetic animals were transplanted by intraportal grafts 6 w eeks later. Islet-transplanted rats returned to euglycemia usually wit hin the first 24 hours after transplantation and remained euglycemic o ver the subsequent II-week observation period. Transplanted animals we re compared with age-matched nontransplanted diabetic rats and nondiab etic age-matched control rats. Successful isotransplantation completel y prevented the characteristic fast twitch (type IIB, glycolytic) fibe r atrophy and also the changes in the fiber-type relative percentages, with prevention of the significant increase in the frequency of slow twitch oxidative (type I) and fast oxidative/glycolytic (type IIA) fib ers at the expense of fast twitch glycolytic (type IIB) fibers. The hi stochemical appearance of all fiber types studied from muscles in tran splanted rats was identical to equivalent fibers in age-matched contro l rats. Our data suggest that diabetic muscle pathology could be rever sed and the progression of diabetic amyotrophy halted through the rest oration of a euglycemic state by successful pancreatic islet transplan tation, at least in shortterm experimental diabetes.