Effect of Paraquat Administration on Antioxidative Enzyme Activities and Oxidative Damage in the Blood and Liver of Senescence-accelerated Mice

The effect was assessed of paraquat administration on the antioxidative defense mechanism in blood and liver. Ten-week-old senescence-accelerated mice were fed with either a 20% casein diet or the same diet supplemented with 200 ppm paraquat for 12 weeks. About 0.2 ml of blood withdrawn periodically from the supraorbital vein was assayed for the activities of antioxidative enzymes and oxidative damage. Blood and liver collected after decapitating the mice were equivalently treated at the end of the experimental period. Paraquat ingestion depressed the antioxidative enzyme activities, and increased the level of oxidized protein in erythrocytes and the thiobarbituric acid-reactive substance (TBARS) value in plasma. Similar changes were observed for the plasma and liver in the antioxidative enzyme activites, and in the level of oxidized protein and the TBARS value. These changes produced by paraquat administration were closely associated with accelerated aging leading to cell death. We discuss the effect of paraquat on senescence in mice, in relation to the oxidative damage caused.