PEROXYNITRITE IN ACETAMINOPHEN INDUCED HEPATOTOXICITY

虽然在治疗剂量下是安全的，但过量的对乙酰氨基酚会产生 小叶中心肝坏死，可致命。每年，都有更多 美国有9000多人因肝损伤而受损 扑热息痛，1996年报告有53人死亡。这样做的理由是 提案是基于我们前期工作的主要发现， 挑战目前公认的毒性范式。它一般都是 公认扑热息痛是由CYP-450代谢成反应性的 代谢物N-乙酰-对苯醌亚胺(NAPQI)，与 谷胱甘肽，导致其消耗(从而减少过氧化氢 解毒)，并随后形成对乙酰氨基酚-蛋白质加合物。 我们的发现表明对乙酰氨基酚对NAPQI的代谢可能不会 是细胞裂解和死亡的唯一决定因素。我们发现， 代谢应激激活驻留细胞，导致合成增加 由一氧化氮和超氧化物组成，它们结合在一起形成 过氧亚硝酸盐。该实体反应生成硝基酪氨酸-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小鼠肝中央小叶细胞内的加合物 老鼠，有毒的部位。因此，基于这个和其他 初步数据，我们提出了对乙酰氨基酚肝毒性的范例 由此产生过氧亚硝酸盐，与对乙酰氨基酚蛋白结合 加合物的形成，协同作用导致细胞溶解和死亡。我们 假设过氧亚硝酸根产生于或作为 对乙酰氨基酚的代谢激活是 对乙酰氨基酚的肝毒性。为了验证这一假设，我们计划进行SA1) 确定扑热息痛的时间和剂量关系 新陈代谢、一氧化氮的形成和毒性的发展；SA2)调查 NO、超氧化物和过氧亚硝酸根的产生在 对乙酰氨基酚通过抑制NO的形成和使用NO而产生的肝毒性， 超氧化物和过氧亚硝酸盐清除剂；以及SA3)识别肝脏 扑热息痛过程中产生NO和超氧化物的细胞 肝脏毒性。通过了解过氧亚硝酸根在体内的作用 对乙酰氨基酚肝毒性，可能开发新的治疗方案 对于肝脏毒性，这种机制可能对其他 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.