Effect of different vitamin E levels on lipid peroxidation in streptozotocin-diabetic rats.

Administration of streptozotocin is used to induce diabetes in experimental models, causing a selective destruction of pancreatic beta islet cells associated with generation of free radicals. Supplementation with antioxidant vitamins such as vitamin E is a protective factor against free radicals. The objective of this study was to determine the effect of administration of a diet supplemented with, or deficient in vitamin E to streptozotocin diabetic rats, controlled or not with insulin, on plasma glucose, hepatic vitamin E and hepatic thiobarbituric acid reactive substance (TBARS) levels before streptozotocin and 24 hours and one and two weeks after drug administration. Deficiency of vitamin E alone increased TBARS levels, and streptozotocin elevated TBARS two times in deficient groups, regardless of insulin control. In rats supplemented with vitamin E, a reduction of plasma glucose and liver vitamin E was observed two weeks after streptozotocin administration (p < 0.05). In conclusion, vitamin E supplementation probably protected against lipoperoxidation and contributed to the absence of elevation of plasma glucose levels, and vitamin E deficiency produced an increase in hepatic TBARS levels in streptozotocin diabetic rats.