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

Abstract

A model for oxidative stress is described in which glutathione (GSH) synthesis is selectively blocked in newborn rats by administration of L-buthionine-(SR)-sulfoxipuine (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 Isieflar bodies and decrease of intraalveolar surfactant. Proximal renal tubular, hepatic, and brain damage also occur. A diastereolsomer of BSO that does not inhibit GSH synthesis, L-buthiflR-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 inkage 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 oxidsative stress, offers an approach to study of other effects of GSH deficiency (e.g., on lipid metabolim, hematopoiesis), and closely resembles oxidative stress that occurs in certain human newborns and in other clinical states.Glutathione (GSH), the ubiquitous peptide thiol that provides cells with their reducing environment, is a key component of the antioxidant system (which includes ascorbate, a-tocopherol, and other compounds) that defends cells against the toxic effects ofoxygen (1-3). GSH is synthesized within cells; its export by many cells is a step in a recycling pathway that seems to protect cell membrane components against oxidative damage (4-6). The functions of GSH may be probed by examining the effects of decreasing cellular GSH. Cellular GSH may be decreased by administering compounds that react with GSH to form conjugates or that oxidize GSH to GSSG; however, these approaches are limited by lack of specificity of the reagents available and, because the effects obtained are transient, are associated with major perturbations of metabolism, or both. Inhibition of GSH synthesis by inhibition of -glutamylcysteine synthetase [rather than of GSH synthetase, whose blockage leads to metabolic acidosis (7,8)] is the preferred approach to a sustained decrease in cellular GSH (9). L-Buthionine-(S,R)-sulfoximine (BSO) and related sulfoximines are highly selective inactivators of -glutamylcysteine synthetase, and their administration to animals turns off cellular GSH synthesis effectively (10-13). BSO does not react with GSH, and there is no evidence that the sulfoximine moiety itself exerts toxicity, a conclusion supported by studies reported here on a diastereoisomer, L-buthionine-(R)-sulfoximine, that does not inhibit GSH synthesis. The effects observed after treatment with BSO, which ...

Role of reactive oxygen species in cis-dichlorodiammineplatinum-induced cytotoxicity on bladder cancer cells

“…The lethal effects of excessive GSH deficiency in animals such as new born rats and guinea pigs appear to be related to multiorgan failure, involving mitochondrial and other damage in liver, kidney and lung (Martensson et al, 1991). Our results also provide significant evidence that GSH depletors induce intracellular GSH deficiency and enhance CDDP-induced cytotoxicity in bladder cancer cells, whereas GSH depletor alone had no significant cytotoxicity effect at the concentration and exposure time used in this study.…”

“…It has been demonstrated that CDDP induced nephrotoxicity can be presented by GSH in renal tissues (Anderson et al, 1990). Furthermore, it has been reported that GSH reacts with ROS and plays a role in the reduction of hydrogen peroxide and organic peroxides (Meister, 1983;Martensson, 1991) and that CDDP is inactivated by direct binding to GSH (Meijer et al, 1990). Ishikawa et al (1993) showed that CDDP reacts with intracellular GSH and that the resulting glutathione-platinum complex is actively exported from leukaemia cells via a GS-X pump.…”

Expression of Multidrug Resistance Protein/GS-X Pump and γ-Glutamylcysteine Synthetase Genes Is Regulated by Oxidative Stress

“…GSH is a well known antioxidant that directly reacts with free radicals and serves as a cofactor for GSH peroxidase to reduce hydrogen peroxide, resulting in reduction of the oxidative cellular environment (38). Using the fluorescent probe DHR123, we demonstrated that reduced ROI levels indeed occurred in several independently established cell lines containing elevated GSH levels (Fig.…”

Glutathione synthetase is dispensable for growth under both normal and oxidative stress conditions in the yeast Saccharomyces cerevisiae due to an accumulation of the dipeptide gamma-glutamylcysteine.

“…This is analogous to the situation in higher eukaryotes, in which depletion of GSH induced by treatment with L-buthionine(S,R)-sulfoximine leads to oxidative tissue damage along with the breakdown of mitochondria (Martensson et al, 1991). Recently, GSH was also found to be essential in Schizosaccharomyces pombe and a role in the detoxification of endogenously derived metabolites via a GSH-conjugate pump was proposed (Chaudhuri et al, 1997).…”