Effect of dietary vitamin E on antioxidant status and antioxidant enzyme activities in Sprague‐Dawley rats

Abstract

The effect of dietary vitamin E on plasma, red blood cells (RBC), hepatic antioxidant status, and antioxidant enzyme activities was investigated. Three groups of six Sprague‐Dawley rats were fed 0, 100, or 1,500 ppm vitamin E for eight weeks. Plasma α‐tocopherol level was increased significantly by increasing dietary vitamin E (p < 0.05). Plasma lipid peroxidation (thiobarbituric acid‐reactive substances) stimulation by 1 mM t‐butyl hydroperoxide was correlated with dietary vitamin E level and was significantly greater in rats fed no vitamin E than in rats fed 100 or 1,500 ppm vitamin E (p < 0.05). RBC reduced glutathione (GSH) level was positively correlated with dietary vitamin E and was significantly greater in rats fed 1,500 ppm vitamin E than in rats fed 0 or 100 ppm vitamin E (p < 0.05). RBC oxidized glutathione was negatively correlated with dietary vitamin E. GSH redox status was expressed as the GSH‐to‐total GSH ratio; the ratio was also positively correlated with dietary vitamin E and was significantly greater in rats fed 1,500 ppm vitamin E than in rats fed no vitamin E (p < 0.05). For antioxidant enzymes, Superoxide dismutase activity in hepatic cytosolic fraction was significantly greater in rats fed 1,500 ppm vitamin E than in rats fed 100 ppm vitamin E. Hepatic GSH reducíase activity was significantly greater in rats fed 100 ppm vitamin E than in rats fed no vitamin E (p < 0.05). Dietary vitamin E had no effect on plasma vitamin C and protein thiol levels. In the systems studied, results indicated that dietary vitamin E selectively influences plasma vitamin E level, RBC GSH status, and hepatic cytosolic Superoxide dismutase and GSH reducíase activities.