维甲酸X受体介导的氧化应激通路在大鼠肺缺血/再灌注损伤中的调控作用

The regulation of retinoid X receptor-mediated oxidative stress pathway in rat pulmonary ischemia/reperfusion injury

本研究旨在探讨维甲酸X受体(retinoid X receptor, RXR)介导的氧化应激通路对大鼠肺缺血/再灌注损伤(pulmonary ischemia/reperfusion injury, PIRI)的干预作用及机制。选取雄性Sprague Dawley (SD)大鼠77只,随机分为7组(n=11):正常对照组(Control组)、假手术组(Sham组)、假手术+9-顺式维甲酸(9-cis retinoid acid,9-cRA,RXR激动剂)组(Sham+9-cRA组)、假手术+HX531 (RXR抑制剂)组(Sham+HX531组)、缺血/再灌注(ischemia/reperfusion, I/R)组、I/R+9-cRA组、I/R+HX531组。采用大鼠在体左侧肺门夹闭30 min再灌注180 min方法制备肺缺血/再灌注(I/R)模型。I/R+9-cRA组和I/R+HX531组大鼠于开胸前腹腔注射9-cRA和HX531。再灌注结束后取左肺组织,评估肺组织损伤,用试剂盒检测肺组织氧化应激等相关指标,用HE染色法和透射电镜分别观察肺组织形态和肺泡上皮细胞超微结构,用免疫荧光标记法观察肺组织RXRα的表达情况,用Western blot检测核因子E2相关因子(nuclear factor E2-related factor 2, Nrf2)蛋白表达情况。结果显示,与Sham组相比,I/R组肺组织出现明显损伤,SOD活性下降,MDA含量和MPO活性升高,Nrf2蛋白表达水平显著降低;与I/R组相比,I/R+9-cRA组肺组织损伤减轻,SOD活性升高,MDA含量和MPO活性下降,RXR和Nrf2蛋白表达水平明显上调。9-cRA的上述改善作用可被HX531逆转。上述结果提示,激动RXR可有效减轻大鼠肺I/R损伤,对肺组织有一定的保护作用,具体机制可能与其激活Nrf2信号途径,增强抗氧化水平,减轻氧化应激反应有关。

The aim of this study was to investigate the regulatory role of retinoid X receptor(RXR)-mediated oxidative stress pathway in rat pulmonary ischemia/reperfusion injury(PIRI)and the underlying mechanism.Seventy-seven male Sprague-Dawley(SD)rats were randomly divided into 7 groups(n=11):control group,sham group,sham+9-cis-retinoid acid(9-cRA,RXR agonist)group,sham+HX531(RXR inhibitor)group,ischemia/reperfusion(I/R)group,I/R+9-cRA group,and I/R+HX531 group.The unilateral lung I/R model was established by obstruction of left lung hilus for 30 min and reperfusion for 180 min in vivo.The rats in I/R+9-cRA and I/R+HX531 groups were given intraperitoneal injection of 9-cRA and HX531 before thoracotomy.After reperfusion,the left lung tissue was taken to evaluate the lung tissue injury,and the oxidative stress-related indexes of the lung tissue were detected by the corresponding kits.The lung tissue morphology and the ultrastructure of the alveolar epithelial cells were observed by HE staining and transmission electron microscope,respectively.The protein expression of RXR in lung tissue was observed by immunofluorescence labeling method,and the expression level of nuclear factor E2-related factor(Nrf2)protein was detected by Western blot.The results showed that,compared with the sham group,the I/R group exhibited obviously injured lung tissue,decreased SOD activity,increased MDA content and MPO activity,and down-regulated expression level of Nrf2 protein.Compared with the I/R group,the I/R+9-cRA group showed alleviated lung tissue injury,increased activity of SOD,decreased MDA content and MPO activity,and up-regulated expression levels of RXR and Nrf2 protein.The above-mentioned improvement effects of 9-cRA were reversed by HX531 treatment.These results suggest that RXR activation can effectively protect the lung tissue against I/R injury,and the mechanism may involve the activation of Nrf2 signaling pathway,the enhancement of antioxidant level and the reduction of oxidative stress response.