Role of Selenium‐Dependent Glutathione Peroxidase in Protecting againstt‐Butyl Hydroperoxide‐Induced Damage in Hepatocytes

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Abstract
The role of the selenoenzyme glutathione peroxidase (Se‐GSHPx) in protecting against oxidative injury was studied in hepatocytes isolated from rats fed either a low‐selenium (Se−) or a selenium‐adequate (Se+, control) diet. In rats fed Se−diet for eight weeks the selenium content of plasma and liver was lowered to 15 and 8%, respectively. No Se‐GSHPx and only 5% of total GSHPx activity was detected in Se−hepatocytes. However, the Se−hepatocytes were as resistant as the Se+cells to oxidative injury by 0.8 mMtert‐butyl hydroperoxide (t‐BuOOH), or 0.2 mMt‐BuOOH plus 1,3‐bis(2‐chloroethyl)‐1‐nitrosourea (BCNU), an inhibitor of oxidized glutathione (GSSG) reductase. Only at 1.5 mMt‐BuOOH or at 0.5 mMt‐BuOOH with BCNU were cell damage and lipid peroxidation more evident in Se−cells. At allt‐BuOOH concentrations used the depletion of cellular glutathione (GSH) was similar in magnitude in Se−and Se+cells, but Se+cells released more glutathione (mainly GSSG), obviously due to their higher Se‐GSHPx activity. These results suggest that hepatocytes devoid of Se‐GSHPx activity maintain a high capacity to resist peroxidative attack, either via residual (non‐Se)GSHPx activity or other compensatory GSH‐associated detoxication mechanisms.

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