不同潮气量机械通气对大鼠肺组织γ-谷氨酰半胱氨酸合成酶和转化生长因子β1的影响

摘要

Objective To explore the effects of the oxidant/autioxidant imbalance on ventilator associated lung injury(Vau),by observing the expressions of γ-glutamylcysteine synthetase(γ-GCS)and transforming growth factor-β_1(TGF-β_1)mRNA and protein during mechanical different ventilation with different tidal volumes in rats.Method Twenty-four male W istar rats were randomly(random number)divided into three groups:control group,low tidal volume group and high tidal volume group,n=8,respectively.The levels of MDA in lung tissue and blood were measured.Immunohistochemical staining and molecular hybridization in situ were employed to determine the expression levels of γ-GCS mRNA and TGF-β_1 mRNA,and protein level in lung tissue.ANOVA(SNK-q)was used to compare difference in groups,and the correlation analysis was carried out.Statistical difference was defined as P＜0.05.Results Compared with control group and low tidal volume group,the levels of MDA in lung tissue and blood,and expressions of TGF-β_1 mRNA and protein level in high tidal volume group were significantly higher(P＜0.01),with the expressions of γ-GCS mRNA decreased(P＜0.01).There was no significant difference between low tidal volume group and control group(P＞0.05).There was a obviously negative correlation between expressions of R-GCS,TGF-β_1 mRNA and protein level in high tidal volume group(r=-0.96 and-0.85,respectively,P＜0.01).Conclusions The high expression of TGF-β_1 mRNA and high protein level,low expression of γ-GCS and reduction of GSH can be induced by high tidal volume ventilation,leading to the imbalance of oxidant/antioxidant system,which is one of the most imporlant causes in Vau.%目的 观察不同潮气量机械通气大鼠肺组织γ-谷氨酰半胱氨酸合成酶(γ-glutamylcysteine synthetase,γ-GCS)和转化牛长因子β_1(transforming growth factor-β_1,TGF-β_1)mRNA及其蛋白表达水平,探讨氧化/抗氧化失衡在呼吸机相关性肺损伤(ventilator associated lung injury,Vau)中的作用.方法 24只雄性Wistar大鼠随机(随机数字法)分为对照组、小潮气量组和大潮气量组(各组8只),测定其肺组织和血浆中MDA含量,并分别采用原位分子杂交技术和免疫组织化学染色法检测肺组织γ-GCS,TGF-β_1,mRNA及其蛋白表达水平,并进行相关性分析.组间差异比较采用方差分析法,各组均数间两两比较采用SNK-q检验,以P＜0.05表示差异有统计学意义,相关性分析采用Pearson直线相关分析法.结果 与对照组和小潮气量组比较,大潮气量组大鼠肺组织和血浆MDA含量、肺组织TGF-β_1mRNA及其蛋白表达水平明显升高(P＜0.01),而γ-GCS mRNA及其蛋白表达水平则明显低于对照组和小潮气量组(P＜0.01);小潮气量组与对照组各项指标比较,差异无统计学意义(P＞0.05).相关分析结果表明大潮气量组大鼠肺气道卜皮细胞γ-GCS和TGF-β_1 mRNA及其蛋白表达均呈负相关(r值分别为-0.96,-0.85,P＜0.01).结论 大潮气量机械通气町诱导肺组织TGF-β_1 mRNA及其蛋白高表达,使γ-GCS表达降低,谷胱甘肽合成减少,导致局部肺组织氧化/抗氧化系统失衡,是VALI发生的重要因素之一.