Inhibition of cytochrome P450 2E1 expression by 2-(allylthio)pyrazine, a potential chemoprotective agent: Hepatoprotective effects
Inhibition of cytochrome P450 2E1 expression by 2-(allylthio)pyrazine, a potential chemoprotective agent: Hepatoprotective effects
复制标题
DOI：
10.1016/s0006-2952(96)00647-8
复制
发表时间：
1997-02-07
影响因子：
5.8
通讯作者：
Kim, SG
中科院分区：
文献类型：
--
作者：
Kim, ND;Kwak, MK;Kim, SG
细胞色素P4502E1(P4402E1)具有解毒和激活有机小分子的功能。观察2-(烯丙硫基)吡嗪(2-AP)对大鼠肝脏P4502E1催化活性及P4502E1表达的影响。2-AP在体外竞争性抑制4-硝基苯酚羟基酶活性(K-I，12 mU M)。2-AP处理大鼠(200 mg/kg/d，po，1~3天)后，P450 2E1的特异性代谢活性下降20-30%，免疫印迹分析也显示，2-AP处理的大鼠肝微粒体中P450 2E1水平显著降低。代谢活性和免疫印迹分析显示，2-AP抑制异烟肼(INH)诱导的肝脏P450 2E1水平。因此，2-AP能有效抑制P450 2E1的原生性和诱导性表达。Northern印迹分析显示，2-AP对肝脏P4502E1mRNA表达有一过性抑制作用，提示2-AP对P4502E1mRNA表达的抑制可能是通过转录失活介导的。观察2-AP对毒物的保护作用。给予致死剂量的扑热息痛(AAP)或异烟肼(INH)的2-AP预处理剂可显著降低毒物引起的死亡率。而血清天冬氨酸氨基转移酶(AST)和丙氨酸氨基转移酶(ALT)水平在AAP给药后显著升高(即9-20倍)，AAP给药前给予2-AP可使升高的血清氨基转移酶活性降低95%。2-AP对CCl4所致的肝毒性也有明显的拮抗作用。CCl4处理使小鼠的转氨酶活性增加35-70倍，而用2-AP(>；10 mg/kg)处理小鼠则可阻断CCl4诱导的肝脏毒性。2-AP的保肝作用部分是通过提高肝脏GSH水平来实现的。而AAP或CCl4处理组小鼠肝脏GSH水平降低70-80%，2-AP处理组小鼠肝脏GSH水平较单独使用AAP或CCl4组升高40-210%。2-AP预处理还可剂量依赖性地减轻AAP或CCl4诱导的脂质过氧化作用。这些代谢活性以及免疫印迹和RNA印迹分析的结果表明，2-AP有效地抑制了结构性和诱导性P450 2E1的表达，并有效地保护了毒物所致的肝脏毒性。版权所有(C)1997 Inc.
Cytochrome P450 2E1 (P440 2E1) is active in both the detoxification and activation of small organic molecules. The effects of 2-(allylthio)pyrazine (2-AP) on P450 2E1-catalytic activity and the expression of rat hepatic P450 2E1 were examined. 2-AP competitively inhibited 4-nitrophenol hydroxylase activity in vitro (K-i, 12 mu M). 2-AP treatment of rats (200 mg/kg/day, po, 1-3 days olc) resulted in 20-30% decreases in the rates of P450 2E1-specific metabolic activities, Immunoblot analysis also revealed that hepatic microsomes isolated from 2-AP-treated rats showed substantial decreases in P450 2E1 level. 2-AP-suppressed isoniazid (INH)-inducible hepatic P450 2E1 levels, as shown by both metabolic activities and immunoblot analyses. Thus, 2-AP was effective in suppressing both constitutive and inducible P450 2E1 expression. Northern blot analysis showed that 2-AP transiently suppressed the hepatic P450 2E1 mRNA level, suggesting that suppression in P450 2E1 expression by 2-AP may be mediated in Dart by transcriptional inactivation. Hepatoprotective effects of 2-AP against toxicants were monitored in mice. 2-AP pretreatment Frier to the administration of lethal doses of acetaminophen (AAP) or INH substantially reduced toxicant-induced mortality. Whereas serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were markedly elevated after AAP administration (i.e. 9-20-fold), 2-AP pretreatment of animals before AAP administration resulted in >95% decreases in elevated serum aminotransferase activities. 2-AP was also effective against CCl4-induced hepatotoxicity. Whereas CCl4 treatment caused 35-70-fold increases in aminotransferase activities, treatment of mice with 2-AP (>10 mg/kg) resulted in the blocking of CCl4-induced liver toxicity. The hepatoprotective effect of 2-AP was in part due to 2-AP-induced elevation of hepatic GSH levels. Whereas AAP or CCl4 treatment resulted in 70-80% reduction in hepatic GSH levels: pretreatment of mice with 2-AP caused a 40-210% elevation in hepatic GSH levels, as compared with either AAP or CCl4 alone. 2-AP pretreatment also reduced AAP- or CCl4-induced increases in lipid peroxidation in a dose-dependent manner. The results of these metabolic activities and of immunoblot and RNA blot analyses demonstrate that 2-AP is efficacious in suppressing constitutive and inducible P450 2E1 expression and effective in protecting against toxicant-induced liver toxicity. Copyright (C) 1997 Inc.