EXPRESSION OF GLUTATHIONE-PEROXIDASE AND CATALASE IN COPPER-DEFICIENTRAT-LIVER AND HEART

Oxidative stress resulting from dietary copper deficiency in rats diff erentially regulates the expression of copper/zinc- and manganese-supe roxide dismutases in the liver and heart. It was hypothesized that the expression of catalase and glutathione peroxidase, the non-copper-con taining antioxidant enzymes, in the rat heart and liver may also be re gulated by dietary copper deprivation. The expression of the activitie s, protein concentrations, and mRNA levels for glutathione peroxidase and catalase were studied in the liver and heart of rats made copper-d eficient for 4 weeks. The activities and mRNA levels for liver seleniu m (Se)-dependent glutathione peroxidase and catalase as well as the im munoreactive protein concentration for the catalase were reduced to a similar extent in copper-deficient animals, which suggests transcripti onal 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 protei n concentration; this indicates that its regulation probably involves both transcriptional and post-translational mechanisms. Se-dependent g lutathione peroxidase was not changed in the heart of copper-deficient rats. These results demonstrate that dietary copper deficiency in rat s differentially alters the expression of Se-dependent glutathione per oxidase and catalase in the liver and heart.