VITAMIN-E EFFECTS ON INDEXES OF LIPID-PEROXIDATION IN MUSCLE FROM DHEA-TREATED AND EXERCISED RATS

Sixty-four male Sprague-Dawley rats were randomly assigned to one of e ight treatment groups to determine the effects of vitamin E (VitE), de hydroepiandrosterone (DHEA), and exercise on antioxidant status in pla sma and skeletal muscle. Indexes of oxidative stress were determined b y measuring two markers of lipid peroxidation and the activity of two free radical scavenging enzymes. One-half of the rats had their diets supplemented with 250 IU VitE/kg of diet. One-half of the rats were in jected with 0.35 mol/kg body wt ip of DHEA-acetate, whereas the others were injected with vehicle. All treatments lasted 5 wk. Before being killed, one-half of each treatment group of rats was randomly assigned to run for 1 h on a motorized rodent treadmill at 21 m/min up a 12% g rade. The other rats remained rested before being killed. Exercise inc reased thiobarbituric acid-reactive substances (TBARS) and lipid hydro peroxides in plasma and TBARS in red slow-twitch and white fast-twitch muscles. VitE reduced the amount of lipid hydroperoxides and TBARS in plasma and TBARS in all three muscle fiber types. VitE also reduced g lutathione peroxidase (GPX) activity in plasma and red fast-twitch mus cle. DHEA increased indexes of oxidative stress in plasma and white fa st-twitch muscle. DHEA reduced GPX activity in plasma but increased GP X activity in all three muscle fiber types. These results indicate tha t aerobic exercise is a mild oxidative stressor with DHEA exacerbating this response and that VitE helps diminish this effect in certain mus cle fiber types.