Superoxide dismutase, catalase and glutathione peroxidase activities in the liver of young and old mice: Linear regression and correlation

Activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GP) were determined in the liver of 15 young (3-5 months) and 15 old (23-26 months) female CBA mice. Although, the activities of all three enzymes decreased in aging, only the SOD decline was statistically significant (P<0.01). The pair wise correlation analysis exhibited an almost identical positive correlation between SOD and CAT in the liver of both young and old mice (r=0.57), whereas the correlative links between the enzymatic pairs of SOD-GP and CAT-GP were increased in aging. Close to zero in the young group (r=-0.08), the coefficient of correlation between SOD and GP became highly significant in the group of old mice (r=0.66; P<0.01). When the coefficients of pair wise and partial correlation were compared, practically no differences were found for the young mice, whereas all three partial coefficients were decreased in the group of old animals. Estimation of the linear regression between the enzymatic pairs revealed higher coefficients of regression and lower intercepts in the group of old mice. The results imply stronger correlative links between the antioxidant enzymes in the liver of old mice, compared with the same indices in the liver of young animals.