Effects of vitamin C on soleus muscle glycogen and oxidative events in experimental diyabetic rats

Increased or uncontrolled oxidative activities play important roles on the pathogenesis of the complications related to chronic diabetic condition. Hyperglycemia causes increasing in the formation of free radicals and reducing in antioxidant amounts by disturbing the pro-oxidant / oxidant balance. Streptozotocin (STZ) is an agent used in creating experimental diabetes. Varying findings have been reported about the striated muscle glycogen levels in diabetes. In this study, it was planned to observe interaction of vitamin C (AA), of which deficiency has been shown in diabetics, with soleus muscle glycogen levels and oxidative events on STZ-diabetic subjects. In the study, 38 male adult Wistar Albino rats with weights 200±20 g were used by separating them into four groups: 1st group: Control (n=9), 2nd group: Vitamin C (n=9, 21 days, i.g., 20 mg/kg), 3rd group Diabetes (n= 10, STZ 45 mg/kg i.p. single dose in the beginning of the experiment), 4th group: Diabetes + Vitamin C ( n=10, applications for 2nd and 3rd groups were performed together). Body weights and fasting blood glucose were measured at the beginning and end of the experiment. Soleus muscles were removed and weighed at the end of the experiment, and AA, Thiobarbituric acid reactive substances (TBARS), Glutathione (GSH), Nitrite + nitrate (NOx) and glycogen levels, and blood AA levels were measured. The results were compared using Anova variance and Mann- Whitney U tests and criterion significance level of P<0.05 was used. Significant loss in body and muscle weight has been shown in diabetics; AA, GSH and NOx levels in the muscle were low and MDA and glycogen levels were high in diabetics; AA levels in blood and muscle increased partially with vitamin C loading; GSH, NOx and glycogen levels were high but (Malondialdehyde) MDA levels were low in muscle of diabetics with vitamin C loading. Large dosages of Vitamin C are required for being effective on metabolic and oxidizing events in diabetics.