Glutathione depletion: Its effects on other antioxidant systems and hepatocellular damage

Abstract

1. The mechanisms of the liver damage produced by three glutathione (GSH)-depleting agents, bromobenzene, allyl alcohol and diethyl maleate, were investigated. 2. With each toxin liver necrosis was accompanied by lipid peroxidation that developed only after severe depletion of GSH. 3. Changes in antioxidant systems by alpha-tocopherol (vitamin E) and ascorbic acid were studied. A decrease in the hepatic level of vitamin E, and a change in the redox state of vitamin C (increase in oxidized over reduced form) were evident whenever extensive lipid peroxidation developed. However, in the case of bromobenzene intoxication these alterations preceded lipid peroxidation, and may be an index of oxidative stress leading to subsequent membrane damage. 4. Experiments carried out with vitamin E-deficient or supplemented diets indicated that pathological phenomena occurring as a consequence of GSH depletion depend on hepatic levels of vitamin E. In vitamin E-deficient animals, lipid peroxidation and liver necrosis appeared earlier than in animals fed the control diet. In animals fed a vitamin E-supplemented diet, bromobenzene and allyl alcohol had only limited toxicity, and diethyl maleate none, in spite of similar hepatic GSH depletion. Thus, vitamin E may largely modulate the expression of toxicity by GSH-depleting agents.