Nrf2／ARE信号通路在硫酸锌预处理减轻大鼠心肌缺血再灌注损伤中的作用

Role of Nrf2/ARE singling pathway in reduction of myocardial ischemia-reperfusion injury by zinc sulfate preconditioning in rats

目的评价转录因子相关因子2（Nrf2）／rE氧化反应元件（ARE）信号通路在硫酸锌预处理减轻大鼠心肌缺血再灌注损伤中的作用。方法SPF级健康雄性sD大鼠，体重250～280g，16～20周龄，采用Langendorff装置建立大鼠离体心脏灌注模型。取模型制备成功的心脏40个，采用随机数字表法分为4组（n=10）：对照组（c组）、缺血再灌注组（I／R组）、硫酸锌预处理组（zn组）和硫酸锌预处理＋Nrf2／ARE信号通路阻断剂毛地黄酮组（Zn＋Lut组）。平衡灌注20min时，c组继续灌注100min；I／R组缺血前灌注4℃的St．Thomas停跳液，32℃下全心缺血40min，恢复灌注60min制备缺血再灌注模型；Zn组腹腔注射200Izmol／L硫酸锌1．5ml／kg，24h后制备模型；Zn＋Lut组于缺血前即刻灌注含毛地黄酮50μmol／L的K—H液3min，其余处理同zn组。分别于平衡灌注末和再灌注末时，记录HR、左心室舒张末压（LVEDP）、左心室发展压（LVDP）和左心室压力最大上升速率（＋dp／dtmax）；于再灌注末取灌注流出液，采用试剂盒检测乳酸脱氢酶（LDH）和丙二醛（MDA）水平；采用Westernblot法检测心肌组织血红素加氧酶-1（HO-1）、醌氧化还原酶1（NQ01）、超氧化物歧化酶1（SODl）和Nrf2的表达水平。结果与C组比较，I／R组和Zn＋Lut组再灌注末HR、＋dp／dtmax和LVDP降低，LVEDP升高，灌注流出液LDH和MDA水平升高，I／R组、zn组和Zn＋Lut组心肌NQOl、HO-1、Nrf2及SODl表达上调（P〈0．05）；与I／R组比较，zn组再灌注末HR、＋dp／dtmax和LVDP升高，LVEDP降低，灌注流出液LDH和MDA水平降低，心肌NQ01、HO-1、Nrf2及SODl表达上调（P〈0.05）；与zn组比较，Zn＋Lut组再灌注末HR、＋dp／dtmax和LVDP降低，LVEDP升高，灌注流出液LDH和MDA水平升高，心肌NQ01、HO-1和SODl表达下调（P〈0．05），Nrf2表达差异无统计学意义（P〉0．05）。结论硫酸锌预处理减轻大鼠心肌缺血再灌注损伤的机制与激活Nrf2／ARE信号通路有关。

Objective To evaluate the role of nuclear factor erythroid 2-related factor 2 （Nrf2）/ antioxidant response element （ARE） singling pathway in reduction of myocardial ischemia-reperfusion （I/R） injury by zinc sulfate preconditioning in rats. Methods SPF healthy male Sprague-Dawley rats, weighing 250-280 g, aged 16-20 weeks, were used in this study. After the animals were anesthetized,their hearts were immediately removed and retrogradely perfused with an oxygenated K-H solution at 37 ℃ in a Langendorff apparatus. Forty isolated rat hearts were randomly divided into 4 groups （n= 10 each） ： con- trol group （group C） , I/R group, zinc sulfate preconditioning group （group Zn） and zinc sulfate precondi- tioning plus Nrf2/ARE singling pathway blocker luteolin group （ group Zn＋Lut）. After 20 min of equilibration, the hearts were continuously perfused for 100 min in group C, the hearts were perfused with 4 ℃ St. Thomas＇ cardioplegic solution before ischemia and then subjected to 40 min global ischemia followed by 60 rain reperfusion to establish the model of I/R in group l/R, 200 Ixmol/L zinc sulfate 1.5 ml/kg was injected intraperitoneally, and 24 h later the model of I/R was established in group Zn, and in group Zn＋Lut, the hearts were perfused for 3 min with K-H solution containing luteolin 50 Ixmol/L starting from the time point immediately before ischemia, and the other treatments were similar to those previously described in group Zn. Heart rate （HR） , left ventrieular end diabetic pressure （LVEDP） , left ventricular developed pressure （LVDP） and the maximum rate of increase of left ventricular pressure （＋dp/dtmax ） were recorded at the end of equilibration and reperfusion. Coronary effluent was collected at the end of reperfusion to measure the lev- els of lactate dehydrogenase （LDH） and malondialdehyde （MDA）. The expression of heme oxygenase-1 （HO-1） , quinone oxidoreduetase （NQO1） , superoxide dismutase 1 （SOD1） and Nrf2 in myocardial tis- sues was detected by Western blot. Results Compared with group C, HR, ＋dp/dt and LVDP were sig- nificantly decreased, LVEDP was increased, and the levels of LDH and MDA in coronary effluent were in- creased at the end of reperfusion in I/R and Zn＋Lut groups, and the expression of NQO1, HO-1, Nrf2 and SOD1 was up-regulated in I/R, Zn and Zn＋Lut groups （P〈0.05）. Compared with group I/R, the HR, ＋ dp/dtx and LVDP were significantly increased, LVEDP was decreased, and the levels of LDH and MDA in coronary effluent were decreased at the end of reperfusion, and the expression of NQO1, HO-1, Nrf2 and SOD1 was up-regulated in group Zn （P〈0.05）. Compared with group Zn, HR, ＋dp/dt and LVDP were significantly decreased, LVEDP was increased, and the levels of LDH and MDA in coronary effluent were increased at the end of reperfusion, and the expression of NQO1, HO-1 and SOD1 was down-regulated （P〈0.05） , and no significant change was found in Nrf2 expression in group Zn＋Lut （P〉0.05）. Conclusion The mechanism by which zinc sulfate preconditioning reduces myocardial I/R injury is related to activation of Nrf2/ARE singling pathway in rats.