DIETARY ALPHA-TOCOPHEROL SUPPLEMENTATION ON ANTIOXIDANT DEFENSES AFTER IN-VIVO IRON OVERLOAD IN RATS

The effect of dietary alpha-tocopherol (alpha-T) supplementation on ir on overload-dependent oxidative damage was studied. Male Wistar rats w ere fed diets supplemented with 2.5% carbonyl iron and/or 200 mg/kg of alpha-tocopheryl acetate for 6 weeks. Oxidation of lipids and protein s were increased by iron overload in rat liver, and alpha-T dietary su pplementation effectively prevented these effects. Iron overload decre ased both, catalase and Mn-superoxide dismutase activities by 49 and 5 4%, respectively, with no effect on glutathione peroxidase activity. a lpha-T supplementation did not prevent the inhibition measured in cata lase and Mn-superoxide dismutase activities. Iron dietary excess had n o effect on liver alpha-T and ubiquinol 9 (UQ9) content. Ubiquinol 10 (UQ10) content after iron overload was decreased by 58 and 54% in whol e liver and liver mitochondria, respectively. alpha-T supplementation led to significant increases in alpha-T, UQ9 and UQ10 content in liver , as compared to control values, and partially prevented the decrease in UQ10 content due to iron excess. The results presented here indicat e that initial stages of iron overload led to oxidative damage in live r (evaluated in terms of lipid and protein oxidation) with a decline i n antioxidant defenses. alpha-T supplementation affected the liver con tent of lipid soluble antioxidants, suggesting a concerted antioxidant response at the cellular level to modulate the effect of excess iron availability. (C) 1997 Elsevier Science Ireland Ltd.