细胞外信号调节激酶1／2在内毒素休克大鼠肺脏血红素氧合酶-±1表达过程中的作用

Effect of extracellular signal-regulated kinases signaling pathway on the expression of heme oxygenase-1 in the lung duringendotoxic shock in rats

目的探讨细胞外信号调节激酶1／2（extracellularsignal-regulatedkinases，ERKl／2）通路在内毒素休克大鼠肺脏内血红素氧合酶-1（hemeoxygenase．1，HO-1）表达过程中作用。方法清洁级雄性sD大鼠48只，体重180g，200g，采用随机数字表法，随机分为4组（每组12只）：假手术组（s组）、内毒素休克组（ss组）、内毒素休克阻断剂组（SE组）和阻断剂组（E组）。±S组和ss组股静脉输注0．1ml二甲亚砜（DMSO），sE组和E组股静脉ERKl／2阻断剂PD9805910μm01／kg（溶于0．1mlDMSO）；30min后，s组和E组分别给予0．5ml生理盐水，ss组和sE组分别给予脂多糖（1ipopolysaccharide，LPS）10ms／ks（溶于0．5ml生理盐水），连续监测平均动脉压（meanaaefialpressure，MAP），2h内ss组和sE组MAP下降≥基础血压25％，认为模型制备成功。根据病理学切片、超氧化物歧化酶（superoxidedismumse，SOD）活性及丙二醛（malondialdehyde，MDA）含量评定肺损伤程度，应用荧光定量PCR技术和Westernblot技术测定ERKl／2和HO．1的表达，判断ERKI通路在内毒素休克大鼠肺脏HO一1表达过程中的作用。结果SS组的病理学评分（4．5±2．1）、肺含水率（81±6）％、MDA含量（3．12±1．30）nm01／mg明显高于S组（2．0±1．0）、（78±5）％、（1．79±0．12）nmol／mg和E组（2．1±1．1）、（77±4）％、（1．83±0．20）nmol／mg（P〈0．05），但低于sE组（6．4±1．3）、（87±5）％、（4．62±0．92）nmol／mg（P〈O．05）；SS组SOD活性（20．2±2．4）NU／mg明显低于S组（30．9±2．9）NU／mg和E组（32．2±1．2）NU／mg（P〈0．05），但高于sE组（14．9±3．2）NU／mg（P〈O．05）；SS组ERKI／2蛋白（0．43±0．09）及p-ERKl／2蛋白（1．46±．22）、HO-lmRNA（1．834±0．023）及HO-1蛋白（1．17±0．25）表达明显高于sE组、s组和E组（P〈0．05）；上述指标在s组和E组之间差异无统计学意义（P〉0．05o结论内毒素休克大鼠给予ERKl／2通路的阻断剂后，肺损伤加重，其机制可能与ERKl／2被阻断后H0．1表达减少有关。

Objective To investigate the effects of extracellular signal-regulated kinases （ERK1/2） signaling pathway on the expression of heme oxygenase-1 （HO-1） in acute lung injury of endotoxic shock induced by lipopolysaccharide （LPS） in rats. Methods Forty-eight pathogen-free male SD rats weighing 180 g-200 g were randomly divided into 4 groups （n=12 each）： sham operation group （group S）,endotoxic shock group （group SS）, endotoxic shock and PD98059 group （group SE） and PD98059 group （group E）. Rats in group S and group SS were administrated with DMSO 0.1 ml intravenously. Rats in Group SE and group E were injected with the inhibitor of ERK1/2 （PD98059） in 0.1 ml DMSO intravenously. 30 min later, rats in Group S and group E received 0.5 ml normal saline intravenously while rats in group SS and group SE received LPS 10 mg/kg in 0.5 ml normal saline intravenously. The invasive arterial pressure was monitored, if there was an initial 25% decrease in mean arterial pressure, then the model can be put to use. The lung injury degree was judged by microscopic examination, moisture content, malondialdehyde （MDA） content and superoxide dismutase （SOD） activity. The ERK1/2 protein, p-ERK1/2 protein and HO-1 protein were measured by Western blot. HO-1 mRNA level were measured by RT-PCR. Results The grade of the pathology （4.5±2.1）, MDA content （3.12±1.30） nmol/mg, moisture content（81±6）% in group SS were significantly higher than that in group S （2.0±1.0）, （78±5）%, （1.79±0.12） nmol/mg and group E （2.1±1.1）, （77±4）%, （1.83±0.20） nmol/mg, （P〈0.05）. But significantly lower than that in group SE（6.4±1.3）, （87± 5 ）%, （4.62±0.92） nmol/mg （P〈0.05）. The SOD activity in group SS （20.2±2.4） NU/mg were significantly lower than that in group S（30.9±2.9） NU/mgand group E （32.2±1.2） NU/mg（P〈0.05）, but significantly higher than that in group SE（14.9±3.2） NU/mg（P〈0. 05）. ERK1/2 protein （0.43±0.09） and p-ERK1/2 protein （1.46±0.22）, HO-lmRNA （1.834±0.023） and HO-1 protein （1.17±0.25） in group SS were significantly higher than that in group S, group SE and group E （P〈0.05）. And there were no significant difference in group S and group P among all the indexes （P〉0.05）. Conehtsions Using the inhibitor of ERK1/2 signaling pathway in endotoxic shock rats worsened lung injury, and its mechanism may be related to decreased HO-1 expression by inhibition of ERK1/2 signaling pathway.