PEROXYNITRITE IN ACETAMINOPHEN INDUCED HEPATOTOXICITY

虽然在治疗剂量下是安全的，但过量的醋氨酚会产生 可能致命的小叶中心性肝坏死 每年，更多 在美国，超过9,000人由于以下原因而遭受肝损伤： 对乙酰氨基酚，1996年报告了53例死亡。 这样做的理由 该提案基于我们初步工作的主要发现， 挑战目前公认的毒性范式。 一般 公认对乙酰氨基酚是由β-450代谢为反应性的 代谢产物N-乙酰基-对苯醌亚胺（NAPQI），与 GSH，导致其耗尽（从而减少过氧化物 解毒），随后形成对乙酰氨基酚-蛋白质加合物。 我们的研究结果表明，对乙酰氨基酚代谢为NAPQI可能不 是细胞溶解和死亡的唯一决定因素。 我们发现 代谢压力激活常驻细胞，导致合成增加 一氧化氮（NO）和超氧化物，它们联合收割机 过氧亚硝酸盐。 该实体反应形成硝基酪氨酸-蛋白质加合物 并具有羟基自由基样活性。我们检测到硝基酪氨酸蛋白 对乙酰氨基酚处理的肝小叶中心细胞中的加合物 小鼠，毒性部位。 因此，根据这一点和其他 初步数据，我们提出了一个范例，对乙酰氨基酚肝毒性 其中过氧亚硝酸盐的产生，与对乙酰氨基酚-蛋白质结合， 加合物形成，协同作用引起细胞裂解和死亡。我们 假设过亚硝酸根在 对乙酰氨基酚代谢活化是 对乙酰氨基酚肝毒性 为了验证这一假设，我们计划SA 1） 确定对乙酰氨基酚与 代谢、NO形成和毒性发展; SA 2）研究 NO、超氧化物和过氧亚硝酸盐的生成在 对乙酰氨基酚通过抑制NO形成和通过使用NO而引起肝毒性， 超氧化物和过氧亚硝酸盐清除剂;和SA 3）识别肝脏 对乙酰氨基酚期间负责产生NO和超氧化物的细胞 肝毒性 通过了解过氧亚硝酸盐在 对乙酰氨基酚肝毒性，可能会开发新的治疗范例 肝毒性，这种机制可能是重要的， 毒素

Although safe at therapeutic doses, overdoses of acetaminophen produce a centrilobular hepatic necrosis that can be fatal. Each year, more than 9,000 individuals in the US sustain liver damage due to acetaminophen, with 53 deaths reported in 1996. The rationale for this proposal is based on key findings from our preliminary work that challenge the currently accepted paradigm of toxicity. It is generally accepted that acetaminophen is metabolized by CYP-450 to the reactive metabolite, N-acetyl-p-benzoquinone imine (NAPQI), which reacts with GSH, leading to its depletion (and thus decreased peroxide detoxification), and subsequently forming acetaminophen-protein adducts. Our findings indicate that metabolism of acetaminophen to NAPQI may not be the sole determinant of cell lysis and death. We find that the metabolic stress activates resident cells, leading to increase synthesis of nitric oxide (NO) and superoxide, which combine to form peroxynitrite. This entity reacts to form nitrotyrosine-protein adducts and has hydroxyl radical like activity. We detect nitrotyrosine-protein adducts in the hepatic centrilobular cells of acetaminophen-treated mice, the site of the toxicity. Thus, based on this and other preliminary data, we propose a paradigm of acetaminophen hepatotoxicity whereby peroxynitrite generation, coupled with acetaminophen-protein adduct formation, act synergistically to cause cell lysis and death. We hypothesize that peroxynitrite generated during or as a result of acetaminophen metabolic activation is a major determinant of acetaminophen hepatotoxicity. To test this hypothesis, we plan to SA1) Determine the time and dose relationships between acetaminophen metabolism, NO formation, and development of toxicity; SA2) Investigate the roles of NO, superoxide, and peroxynitrite generation in acetaminophen hepatotoxicity by inhibiting NO formation and by using NO, superoxide, and peroxynitrite scavengers; and SA3) Identify the liver cells responsible for NO and superoxide generation during acetaminophen hepatotoxicity. By understanding the role of peroxynitrite in acetaminophen hepatotoxicity, new treatment paradigms may be developed for hepatotoxicity, and this mechanism may be important with other toxins.