Vitamin E regulates changes in tissue antioxidants induced by fish oil andacute exercise

Purpose: Prooxidant effects of fish oil supplementation could unfavorably a ffect the cardiovascular benefits of fish oil. We tested the effects of 8 w k vitamin E cosupplementation with fish oil on antioxidant defenses at rest and in response to exhaustive exercise in rats. Methods: Rats (N = 80) wer e divided into fish oil, fish oil and vitamin E (FOVE), soy oil, and soy oi l and vitamin E (SOVE) supplemented groups. For the vitamin E supplemented rats, corresponding groups (FOVE-Ex and SOVE-Ex) performed an acute bout of exhaustive exercise after the supplementation period. Results: Fish oil su pplementation increased the activity of catalase, glutathione peroxidase, a nd glutathione-S-transferase in the liver and red gastrocnemius (RG) muscle . Fish oil decreased liver total glutathione (TGSH) levels. Vitamin E suppl ementation decreased antioxidant enzyme activities to levels at or near tho se in SOVE in a tissue specific pattern. Vitamin E increased TGSH in liver, heart, and RG. Regression analysis showed TGSH to be a negative determinan t of protein oxidative damage as measured by protein carbonyl levels in bot h liver and RG. Catalase activity was associated with liver lipid peroxidat ion as measured by thiobarbituric acid-reacting substances. The exercise-in duced decrease in hepatic TGSH tended to be less in FOVE versus SOVE. Exhau stive exercise also modulated tissue antioxidant enzymes. Conclusions: Vita min E supplementation markedly decreased fish oil induced antioxidant enzym e activities in all tissues. Sparing of glutathione may be an important mec hanism by which vitamin E decreased tissue protein oxidative damage.