Inhibition of streptozotocin -induced oxidative stress by vitamin E and selenium supplementation in diabetic rats

Many studies have shown that oxidative stress is increased in diabetes and may accelerate the development of complications through the metabolism of excessive glucose and free fatty acids. In the present study, the effects of two well-known antioxidative nutrients, vitamin E and selenium, on the oxidative stress and antioxidative systems in streptozotocin (STZ) induced diabetic rats have been investigated. Thirty two adult female Sprague Dawley rats were randomly divided into three groups of normal control, diabetic control and diabetic vitamin E+selenium-supplemented groups. Diabetes was induced in the second and third group by STZ (60 mg/kg, i.p) and third group received both vitamin E (300 mg/kg/day) and selenium (0.5 mg/kg/day) for a period of 30 days. Fasting serum glucose concentration, malondialdehyde (MDA) level, glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities, plasma total antioxidant status (TAS) and lipid profile were measured. In diabetic rats, a significant increase in the levels of fasting plasma glucose (p 0.001) and MDA (p<0.05) was observed, whereas plasma TAS (p<0.01) and erythrocyte SOD activity (p<0.05) significantly decreased with no change in the GPX activity (p>0.05). Oral administration of vitamin E and selenium led to a significant decrease in the fasting plasma glucose levels (p<0.05). It also improved the antioxidant status of diabetic rats possibly through decreasing lipid peroxidative products and increasing enzymatic antioxidants. According to the results obtained vitamin E and selenium supplementation has antioxidant effect in STZ-induced experimental diabetes and may have beneficial protective effects in diabetic oxidative damage.