Acetaminophen-Induced Hepatotoxicity in Mice Occurs with Inhibition of Activity and Nitration of Mitochondrial Manganese Superoxide Dismutase
Acetaminophen-Induced Hepatotoxicity in Mice Occurs with Inhibition of Activity and Nitration of Mitochondrial Manganese Superoxide Dismutase
复制标题
DOI：
10.1124/jpet.110.176321
复制
发表时间：
2011-04-01
影响因子：
3.5
通讯作者：
Hinson, Jack A.
中科院分区：
文献类型：
--
作者：
Agarwal, Rakhee;MacMillan-Crow, Lee Ann;Hinson, Jack A.
过量使用镇痛/解热药对乙酰氨基酚（APAP）时，会产生肝毒性。毒性是由肝脏代谢为N-乙酰基-对苯醌亚胺（NAPQI）介导的。在低剂量后，NAPQI被GSH有效地解毒。然而，在过量的GSH耗尽，NAPQI共价结合到蛋白质作为APAP加合物，和氧/氮应激发生。据信毒性是由线粒体功能障碍引起的。据报道，锰超氧化物歧化酶（MnSOD）的蛋白质硝化失活发生在其他氧化应激介导的疾病。MnSOD是一种重要的线粒体抗氧化酶，可防止线粒体内过氧亚硝酸盐的形成。为了检查MnSOD在APAP毒性中的作用，用300 mg/kg APAP处理小鼠。GSH在0.5 h时显著降低65%，并从1 h至4 h保持降低。血清丙氨酸氨基转移酶直到4小时才显著升高，6小时为2290 IU/L。MnSOD活性在1h和2h显著降低50%。在1小时，GSH显着耗尽62%和80%，在无毒剂量为50和100毫克/公斤，分别。200和300 mg/kg APAP肝毒性剂量下未发生进一步GSH耗竭。APAP在100、200和300 mg/kg剂量下观察到MnSOD活性的剂量反应性降低。免疫沉淀MnSOD从APAP处理的小鼠的肝脏，然后通过Western印迹分析显示硝化MnSOD。未检测到APAP-MnSOD加合物。用NAPQI处理重组MnSOD不产生APAP蛋白加合物。数据表明，MnSOD的硝化失活是APAP诱导的肝毒性的早期事件。
In overdose the analgesic/antipyretic acetaminophen (APAP) is hepatotoxic. Toxicity is mediated by initial hepatic metabolism to N-acetyl-p-benzoquinone imine (NAPQI). After low doses NAPQI is efficiently detoxified by GSH. However, in overdose GSH is depleted, NAPQI covalently binds to proteins as APAP adducts, and oxygen/nitrogen stress occurs. Toxicity is believed to occur by mitochondrial dysfunction. Manganese superoxide dismutase (MnSOD) inactivation by protein nitration has been reported to occur during other oxidant stress-mediated diseases. MnSOD is a critical mitochondrial antioxidant enzyme that prevents peroxynitrite formation within the mitochondria. To examine the role of MnSOD in APAP toxicity, mice were treated with 300 mg/kg APAP. GSH was significantly reduced by 65% at 0.5 h and remained reduced from 1 to 4 h. Serum alanine aminotransferase did not significantly increase until 4 h and was 2290 IU/liter at 6 h. MnSOD activity was significantly reduced by 50% at 1 and 2 h. At 1 h, GSH was significantly depleted by 62 and 80% at nontoxic doses of 50 and 100 mg/kg, respectively. No further GSH depletion occurred with hepatotoxic doses of 200 and 300 mg/kg APAP. A dose response decrease in MnSOD activity was observed for APAP at 100, 200, and 300 mg/kg. Immunoprecipitation of MnSOD from livers of APAP-treated mice followed by Western blot analysis revealed nitrated MnSOD. APAP-MnSOD adducts were not detected. Treatment of recombinant MnSOD with NAPQI did not produce APAP protein adducts. The data indicate that MnSOD inactivation by nitration is an early event in APAP-induced hepatic toxicity.