不同潮气量机械通气对大鼠肺组织激活蛋白-1、γ-谷氨酰半胱氨酸合成酶的影响

Effects of different tidal ventilation on the expression of active protein-1 and γ-glutamylcysteine synthetase in lung of rats

目的通过观察不同潮气量机械通气对大鼠肺组织激活蛋白-1(AP-1)和γ-谷氨酰半胱氨酸合成酶(γ-GCS)表达的影响,探讨氧化-抗氧化系统失衡在呼吸机所致肺损伤(VILI)发生中的作用。方法 24只雄性Wistar大鼠随机分为对照组、小潮气量(L-VT)组和大潮气量(H-VT)组,每组8只。光镜下观察各组大鼠肺组织病理损伤程度;采用硫代巴比妥酸比色法测定大鼠血浆及肺组织中丙二醛(MDA)含量,原位分子杂交技术和免疫组织化学染色法检测肺组织AP-1和γ-GCS mRNA及其蛋白表达水平。结果 H-VT组大鼠肺组织和血浆中MDA含量明显高于对照组和L-VT组(均P<0.01),肺组织病理损伤程度较对照组和L-VT组明显加重;L-VT组与对照组比较差异无统计学意义(P>0.05)。H-VT组肺组织γ-GCSm RNA及其蛋白表达水平明显低于对照组和L-VT组(均P<0.01),而AP-1mRNA及其蛋白表达水平明显高于对照组和L-VT组(均P<0.01),L-VT组与对照组比较差异均无统计学意义(P>0.05)。结论大潮气量机械通气通过上调肺组织AP-1 mRNA及其蛋白表达,抑制γ-GCS活性,导致肺组织局部谷胱甘肽合成减少和氧化-抗氧化系统失衡,可能是VILI发生的重要因素之一。

Objective To explore the effect of the oxidant/antioxidant imbalance on ventilator induced lung injury （VILI） by observing the expression of active protein-1 （AP-1）, γ-glutamylcysteine synthetase（ γ- GCS） mRNA and protein on different tidal volumes in lung of rats. Methods Twenty-four male Wistar rats were divided into three groups randomly： control group, low tidal volume （L-VT） group and high tidal volume （H-VT） group. The pathologic alterations of the lungs were observed under light microscope in groups. The levels of methane diearboxylic aldehyde （ MDA ） in lung and blood were measured by Thiobarbituric acid method. Immunohistoehemical staining and molecular hybridization in situ were employed to determine the expression level of AP-1 and γ-GCS mRNA and protein in pulmonary tissues. Results Comparing with control group and low tidal volume group, the levels of MDA in lung and blood were highly significant in high tidal volume group （P 〈0.01 ）; There was more obvious pathologic alterations in the H-VT group. There was no statistics meaning for the differences between low tidal volume group and control group （ P 〉 0.05 ）. Comparing with control group and low tidal volume group, the expression of AP-1 mRNA and protein were highly significant （P 〈0.01 ） in high tidal volume group, with the expression of 5,-GCS decreased （P 〈0.01 ）; There was no statistics meaning for the differences between low tidal volume group and control group （P 〉 0. 05 ）. Conclusions The over expression of AP-1 mRNA and protein, low expression of γ-GCS and reduction of GSH can be induced by high tidal volume ventilation, which can lead to the imbalance of oxidant/antioxidant system. It is one of the most important factors in VILI.