1,3-Dinitrobenzene metabolism and GSH depletion.
1,3-Dinitrobenzene metabolism and GSH depletion.
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1,3-二硝基苯代谢和 GSH 消耗。
DOI：
10.1021/tx0155552
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发表时间：
2002
影响因子：
4.1
通讯作者：
Miller,MarionG
中科院分区：
文献类型：
--
作者：
Reeve,IanT;Voss,JohnC;Miller,MarionG
先前的工作表明，大鼠曲细精管的线粒体部分能够代谢1，3-二硝基苯，使用NADPH作为辅因子。此外，1，3-二硝基苯处理大鼠肾小管引起线粒体GSH水平下降。1，3-二硝基苯的原位线粒体代谢可能通过产生活性氧中间体，产生氧化应激和/或一种或多种与GSH发生非酶反应的1，3-二硝基苯代谢物而导致这种消耗。本研究的目的是调查这两个潜在的机制可能导致所观察到的GSH耗竭。已知肝微粒体快速代谢1，3-二硝基苯，当与1，3-二硝基苯和NADPH孵育时产生超氧阴离子自由基。然而，与生精小管线粒体，没有检测到氧自由基。因此，上述GSH耗竭不太可能是由于1，3-二硝基苯的原位线粒体代谢产生活性氧中间体所致。为了研究1，3-二硝基苯代谢产物消耗曲细精管线粒体GSH的能力，将线粒体与1，3-二硝基苯和NADPH孵育。GSH的损失与1，3-二硝基苯代谢产物硝基苯羟胺和硝基苯胺的出现相关。随后的研究表明，代谢产物，亚硝基硝基苯，已知与非蛋白巯基非酶反应，和硝基苯羟胺都氧化生精小管线粒体GSH。进一步的研究表明硝基苯羟胺可以通过自由基机制消耗GSH。在水溶液中，这种代谢物被证明与自由基形式（被认为是氢氮氧自由基）平衡存在。GSH的加入消除了信号，这意味着自由基与GSH发生非酶反应。总之，本研究中的数据表明，在DNB处理的曲细精管中观察到的线粒体GSH的减少是由于NPHA和NNB的形成，而不是活性氧中间体。
Previous work demonstrated that the mitochondrial fraction of rat seminiferous tubules is capable of metabolizing 1,3-dinitrobenzene, using NADPH as a cofactor. Moreover, 1,3-dinitrobenzene treatment of rat tubules caused a decrease in mitochondrial GSH levels. In situ mitochondrial metabolism of 1,3-dinitrobenzene may have caused this depletion through the production of reactive oxygen intermediates, generating oxidative stress and/or one or more metabolites of 1,3-dinitrobenzene which reacted nonenzymatically with GSH. The goal of this study is to investigate which of these two potential mechanisms may have caused the observed GSH depletion. Liver microsomes, known to rapidly metabolize 1,3-dinitrobenzene, generated the superoxide anion radical when incubated with 1,3-dinitrobenzene and NADPH. However, with the seminiferous tubule mitochondria, no oxygen radicals were detected. Hence, the aforementioned GSH depletion is unlikely due to the production of reactive oxygen intermediates from in situ mitochondrial metabolism of 1,3-dinitrobenzene. To investigate the ability of 1,3-dinitrobenzene metabolites to deplete seminiferous tubule mitochondrial GSH, mitochondria were incubated with 1,3-dinitrobenzene and NADPH. Loss of GSH correlated with the appearance of the 1,3-dinitrobenzene metabolites, nitrophenylhydroxylamine and nitroaniline. Subsequent investigation demonstrated that the metabolites, nitrosonitrobenzene, known to react nonenzymatically with nonprotein sulfhydryls, and nitrophenylhydroxylamine both oxidized seminiferous tubule mitochondrial GSH. Further studies suggested that nitrophenylhydroxylamine could deplete GSH via a free radical mechanism. In aqueous solution, this metabolite was shown to exist in equilibrium with a radical form, thought to be the hydronitroxide radical. The addition of GSH eliminated the signal, implying that the radical reacted nonenzymatically with GSH. In conclusion, the data in this study suggest that the decrease in mitochondrial GSH observed in DNB-treated seminiferous tubules is due to the formation of NPHA and NNB and not reactive oxygen intermediates.