Inhibition of glutathione synthesis in the newborn rat: a model for endogenously produced oxidative stress.

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RESUMO

A model for oxidative stress is described in which glutathione (GSH) synthesis is selectively blocked in newborn rats by administration of L-buthionine-(S,R)-sulfoximine (BSO). In this model, the normal endogenous physiological formation of reactive oxygen species is largely unopposed, and therefore oxidative tissue damage occurs; because GSH is used for reduction of dehydroascorbate, tissue ascorbate levels decrease. In lung there are decreased numbers of lamellar bodies and decrease of intraalveolar surfactant. Proximal renal tubular, hepatic, and brain damage also occur. A diastereoisomer of BSO that does not inhibit GSH synthesis, L-buthionine-R-sulfoximine, does not produce toxicity; this control experiment renders it unlikely that the observed effects of BSO are produced by the sulfoximine moiety itself. There is correlation between the decrease of mitochondrial GSH levels and mitochondrial and cell damage. Oxidative stress as evaluated by mitochondrial damage and mortality can be prevented by treatment with GSH esters or ascorbate. There is apparent linkage between the antioxidant actions of GSH and ascorbate. This model, which may readily be applied to evaluation of the efficacy of other compounds in preventing oxidative stress, offers an approach to study of other effects of GSH deficiency (e.g., on lipid metabolism, hematopoiesis), and closely resembles oxidative stress that occurs in certain human newborns and in other clinical states.

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