氯沙坦对百草枯中毒致大鼠肺损伤的改善作用及与ACE2/Ang-(1-7)/Mas受体轴表达的关系

摘要

目的 分析氯沙坦对百草枯中毒致大鼠肺损伤的改善作用及与ACE2/Ang-(1-7)/Mas受体轴表达的关系.方法 将36只清洁级雄性SD大鼠随机分为对照组、模型组和实验组,三组各12只.对照组给予生理盐水;模型组给予百草枯溶液18 mg/kg,于一次性腹腔注射;实验组给予百草枯溶液18 mg/kg,于一次性腹腔注射,待0.5 h后应用氯沙坦溶液进行灌胃,每日10 mg/kg.1周、2周、3周取各组大鼠肺组织,对其肺系数进行计算以评估其肺水肿的状况;采用HE染色对各组大鼠肺泡炎的程度进行观察,并用Masson染色评估大鼠肺纤维化的严重程度;采用酶联免疫吸附试验法检测各组大鼠肺组织匀浆中Ang-(1-7)和转化生长因子β1(TGF-β1)的水平,并通过免疫组织化学法对各组大鼠肺组织中Mas受体和血管紧张素转换酶II(ACE2)蛋白的表达水平进行检测.结果 在染毒后1周、2周、3周时,模型组和实验组肺系数较对照组均显著升高(P ＜0.01),而实验组各时间点时的肺系数较模型组均显著下降(P ＜0.01).在染毒后1周、2周、3周,模型组出现明显肺泡炎症,且随着染毒时间的增加,可出现肺纤维化,实验组肺泡炎症程度轻于模型组,实验组肺纤维化程度较模型组明显减轻.随着染毒时间的增加,Ang-(1-7)和TGF-β1在模型组与实验组肺组织匀浆中的水平均逐渐升高,且模型组与实验组各时间点Ang-(1-7)和TGF-β1的含量较对照组均显著升高(P ＜0.01);染毒后1、2、3周,Ang-(1-7)在实验组肺组织匀浆中的水平较模型组明显升高,而TGF-β1的含量较模型组显著下降(P ＜0.01).随着染毒时间的增加,模型组与实验组大鼠肺组织中Mas受体和ACE2蛋白的表达水平均显著升高(P ＜0.05),且实验组染毒后2周、3周Mas受体和ACE2蛋白的表达水平较模型组均显著升高(P＜0.05).结论 在百草枯中毒后,肺组织匀浆中Ang-(1-7)和TGF-β1的表达水平明显上调,而氯沙坦可能通过升高ACE2/Ang-(1-7)/Mas受体轴的表达水平而起到下调纤维化因子TGF-β1表达的作用,因此可改善百草枯中毒所引起的肺损伤和肺纤维化的形成.%Objective To analyze the effect of losartan on lung injury induced by paraquat poisoning and its relationship with the expression of ACE2/Ang- (1-7) /Mas receptor axis. Methods 36 male SD rats of clean grade were randomly divided into control group, model group and experimental group with 12 rats in each group. The control group was given normal saline; the model group was given paraquat solution 18 mg/kg, once intraperitoneal injection. The experimental group was given paraquat solution 18 mg/kg, once intraperitoneal injection, after 0. 5 hours, losartan solution was given intragastrically, 10 mg/kg per day. Pulmonary tissue was taken from each group and its pulmonary coefficients were calculated to evaluate the status of pulmonary edema. The degree of alveolitis was observed by HE staining, and the severity of pulmonary fibrosis was assessed by Masson staining. The levels of Ang- (1-7) and transforming growth factor-β1 (TGF-β1) in lung homogenate were detected by enzyme-linked immunosorbent assay (ELISA). The expression levels of Mas receptor and angiotensin converting enzyme II (ACE2) protein in lung tissues of rats in each group were detected by immunohistochemistry. Results At 1, 2 and 3 weeks after exposure, the lung coefficient of model group and experimental group was significantly higher than that of control group (P ＜ 0. 01), while the lung coefficient of experimental group at each time point was significantly lower than that of model group (P ＜ 0. 01). At 1 and 2 weeks after exposure, alveolar inflammation appeared in the model group, and pulmonary fibrosis appeared with the increase of exposure time. At 1 and 2 weeks after exposure, the degree of alveolar inflammation in the experimental group was less than that in the model group. At 2 and 3 weeks after exposure, the degree of pulmonary fibrosis in the experimental group was significantly less than that in the model group. With the increase of exposure time, the levels of Ang- (1-7) and TGF-β1 in lung homogenate of model group and experimental group increased gradually, and the levels of Ang- (1-7) and TGF-β1 in model group and experimental group were significantly higher than those in control group at each time point (P ＜ 0. 01). At 1, 2 and 3 weeks after exposure, the levels of Ang- (1-7) in lung homogenate of experimental group were significantly higher than those of model group, while the levels of TGF-beta 1 were significantly higher than those of model group. Type A group decreased significantly (P ＜ 0. 01). With the increase of exposure time, the expression levels of Mas receptor and ACE2 protein in the lung tissue of model group and experimental group were significantly increased (P ＜ 0. 05). The expression levels of Mas receptor and ACE2 protein in the experimental group were significantly higher than those in the model group at 2 and 3 weeks after exposure (P ＜0. 05). Conclusion After paraquat poisoning, the expression of Ang- (1-7) and TGF-β1 in lung homogenate is significantly up-regulated, and losartan can down-regulate the expression of fibroblast factor TGF-β1 by increasing the expression of ACE2/Ang- (1-7) /Mas receptor axis, which can improve the formation of lung injury and pulmonary fibrosis caused by paraquat poisoning.