Effects of aging and food restriction on the antioxidant enzyme activity of rat livers.

The effects of aging and food restriction on the activities and mRNA levels of antioxidant enzymes in rat livers were examined. Rats were fed ad libitum every day (AL) or ad libitum on every other weekday (FR). At 30 months of age, the catalase and glutathione peroxidase activities were lower, whereas the thiobarbituric acid (TBA) value, an index of lipid peroxidation of the AL rats, was higher than that at younger ages. At 33 months of age, copper/zinc superoxide dismutase (CuZnSOD), catalase, and glutathione peroxidase activities increased, and the TBA value of the FR rats remained unchanged as compared with those at younger ages. Until old age, food restriction gave rather decreasing effects on antioxidant enzyme activities. Furthermore, antioxidant enzyme activities and the TBA values of the FR rats were higher at the end of a fasting period than those at the end of a feeding period.