Effects of Vitamin C on Muscle Ultrastructure in Experimental Diabetes

This study investigated the effects of streptozotocin (STZ)-induced diabetes on the ultrastructure of the gastrocnemius muscle in rats. Thirty-eight adult male Wistar Albino rats (200 ± 20 g) were randomly assigned to four experimental groups: Control, Vitamin C, Diabetes, and Diabetes + Vitamin C. Vitamin C, a wellestablished antioxidant, was administered to evaluate its potential protective effects. Diabetes was induced via intravenous injection of STZ dissolved in sterile physiological saline. The ultrastructural morphology of type I, type IIa, and type IIb muscle fibers in the gastrocnemius was examined in all groups using transmission electron microscopy. In diabetic rats, type I and IIa fibers exhibited pronounced mitochondrial damage, characterized by the loss of cristae, an increased accumulation of lipid droplets, and irregular nuclear morphology. Additionally, type IIb fibers demonstrated disorganization of the T-tubular system. These findings suggest that STZ-induced diabetes leads to fiber-typespecific ultrastructural alterations in skeletal muscle. Notably, in diabetic rats receiving Vitamin C supplementation, type I and IIa fibers displayed only mild mitochondrial alterations, fewer lipid droplets, and a preserved T-tubular organization, indicating a potential protective role of Vitamin C against diabetes-induced muscle damage.