Effects of age and strain on small intestinal and hepatic antioxidant defense enzymes in Wistar and Fisher 344 rats.

Age- and strain-associated alterations in intestinal and hepatic antioxidant defense enzymes including superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and glutathione-S-transferase (GST), and lipid peroxidation were examined in Wistar and F344 rats of both strains aged 2 weeks, 2.5, 10 and 23 months. In the small intestine, activities of SOD and GSH-PX and lipid peroxidation were not affected by age or strain difference. Intestinal GST activity was noticeably increased with age in both strains, but somewhat different pattern of age-related changes occurred between two strains. Wistar rats aged 23 months had a significantly higher intestinal GST activity than corresponding age of F344 rats. In the liver, cytosolic SOD activity was not affected by age and strain, whereas GSH-PX and GST activities and lipid peroxidation were markedly influenced by age or strain difference. In particular, hepatic GSH-PX in Wistar rats resulted in a significant increase after 10 months of age and stayed at this level till 23 months of age we examined. Also, Wistar rats showed a higher lipid peroxidation in the liver of 2.5 months old when compared with corresponding age of F344 rats. However, F344 rats did not show any significant age-dependent changes in GSH-PX and lipid peroxidation. In contrast, the GST activity did show much of an age-associated alteration in both strains. Age-associated change in GST activity of Wistar rats was much greater than that observed in F344 rats, especially late in the lifetime (23 months old). It is concluded from our results that age has profound impact on development of some antioxidant enzymes in the small intestine and liver and also strain-related difference in development of antioxidant defense system was observed at least some time of rat life.