Effect of Supplementation of Diet with Vitamin C on Induction and Consequences of STZ-Diabetes in Rats

OBJECTIVE: Streptozotocin (STZ) destroys the beta cells of pancreas by generation of reactive oxygen species and vitamin C has documented antioxidant properties. This study was designed to evaluate the preventive effect of supplementation of diet by vitamin C on induction of STZ-diabetes and its effect on carbohydrate and lipid metabolism of diabetic rats. MATERIALS AND METHODS: Fifty male Wistar rats were divided randomly into non-diabetic (ND), diabetic (D), C۱, C۲ and C۳ groups. The diet of C۱, C۲ and C۳ groups were supplemented with ۲.۵, ۵ and ۱۰ g/kg of vitamin C, respectively. Four days later all groups except ND, were made diabetic by IP injection of STZ and blood glucose was measured ۷۲ h later to determine the severity of blood glucose elevation. Weight gain was measured weekly. ۲۱ days after induction of diabetes Glycosylated hemoglobin (HbA۱C), triglyceride (TG), total cholesterol (TC), HDL-c and LDL-c were measured or calculated in plasma of ۶ diabetic rats in each groups that their glucose was more than ۲۰۰ mg/dl after STZ injection. RESULTS: Vitamin C significantly prevented blood glucose elevation after STZ injection in group C۲. Weight gain decreased in all diabetic groups. Increase of HbA۱c could not be prevented by vitamin C in any groups. TC and LDL-c decreased and HDL% increased in group C۳. CONCLUSION: We suggest that the amount of vitamin C consumption may have an important effect on STZ-diabetes induction and it may be in agreement with opposite effects of free radicals on insulin receptor signaling. Furthermore, vitamin C may have some beneficial effects on lipid metabolism disorders of diabetes.

Keywords:

Diabetes , Streptozotocin , Ascorbic acid , Prevention , Diet , HDL-c , LDL-c