EXPRESSION OF GLUTATHIONE-PEROXIDASE AND CATALASE IN COPPER-DEFICIENT RAT-LIVER AND HEART

Oxidative stress resulting from dietary copper deficiency in rats differentially regulates the expression of copper/zinc- and manganese-superoxide dismutases in the liver and heart. It was hypothesized that the expression of catalase and glutathione peroxidase, the non-copper-containing antioxidant enzymes, in the rat heart and liver may also be regulated by dietary copper deprivation. The expression of the activities, protein concentrations, and mRNA levels for glutathione peroxidase and catalase were studied in the liver and heart of rats made copper-deficient for 4 weeks. The activities and mRNA levels for liver selenium (Se)-dependent glutathione peroxidase and catalase as well as the immunoreactive protein concentration for the catalase were reduced to a similar extent in copper-deficient animals, which suggests transcriptional regulation. The mRNA, activity, and protein concentration for the myocardial catalase were increased in copper-deficient rats. However, the increase was larger for the mRNA than for the activity and protein concentration; this indicates that its regulation probably involves both transcriptional and post-translational mechanisms. Se-dependent glutathione peroxidase was not changed in the heart of copper-deficient rats. These results demonstrate that dietary copper deficiency in rats differentially alters the expression of Se-dependent glutathione peroxidase and catalase in the liver and heart.