title: The regeneration of reduced glutathione in rat forebrain mitochondria identifies metabolic pathways providing the NADPH required.
abstract: Metabolic pathways underlying the regeneration of reduced glutathione were investigated in acutely isolated metabolically active mitochondria from rat forebrain. The application of hydrogen peroxide to the organelles was accompanied by a transient increase in glutathione disulfide. The recovery of reduced glutathione was significantly improved in the presence of alternatively succinate, malate, citrate, isocitrate, or beta-hydroxybutyrate. Inhibition of succinate dehydrogenase by malonate abolished the beneficial effect of succinate on the reduction of glutathione disulfide but did not influence the effect of isocitrate. Fluorocitrate, an inhibitor of aconitase, blocked the effect exerted by citrate but did not inhibit the effects of malate or beta-hydroxybutyrate. Uncoupling of the respiratory chain by carbonyl cyanide m-chlorophenylhydrazone prevented the beneficial effect of beta-hydroxybutyrate but did not abolish the improved reduction of mitochondrial glutathione disulfide in the presence of malate and isocitrate. These results suggest that NADP+-dependent isocitrate dehydrogenase as well as malic enzyme and nicotinamide nucleotide transhydrogenase contribute to the regeneration of NADPH required for the reduction of glutathione disulfide in brain mitochondria.
authors.affiliation: Physiologisch-chemisches Institut der Universität Tübingen, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Vogel
authors.forename: H
authors.initials: H
authors.lastname: Wiesinger
authors.forename: B
authors.initials: B
authors.lastname: Hamprecht
authors.forename: R
authors.initials: R
authors.lastname: Dringen
mesh_terms: D000818:Animals; D005978:Glutathione / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D008291:Malate Dehydrogenase / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D009250:NADP Transhydrogenases / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D016548:Prosencephalon / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D009249:NADP; D006861:Hydrogen Peroxide; D008291:Malate Dehydrogenase; D007521:Isocitrate Dehydrogenase; D009250:NADP Transhydrogenases; D005978:Glutathione