依托咪酯后处理肢体缺血再灌注肺损伤模型大鼠Fas/Fasl通路的变化

Variation of Fas/Fasl pathway in limb ischemia-reperfusion lung injury rats after etomidate post-treatment

背景:目前文献已证实依托咪酯预处理可减轻肢体缺血再灌注对远隔脏器造成的损伤,但依托咪酯后处理对肢体缺血再灌注对远隔脏器是否有保护作用及其机制,目前报道甚少。目的:观察依托咪酯后处理对肢体缺血再灌注肺损伤的影响。方法:将大鼠采用夹闭双侧股动脉2 h、再灌注3 h的方法制备肢体缺血再灌注肺损伤模型,设为模型组;于大鼠肢体缺血2 h后,经尾静脉分别注射依托咪酯1.0 mg/kg或地塞米松0.2,0.5和1.0 mg/kg,分别设为依托咪酯后处理组、地塞米松0.2,0.5,1.0 mg/kg组。各组于再灌注3 h时经颈动脉取血,行动脉血气分析,记录血氧分压。随后取大鼠肺组织采用免疫组织化学染色检测病理变化、应用Hoechst33258染色法检测肺细胞凋亡指数以及检测肺湿/干质量比;应用WestenBlot法和RT-PCR法分别测定肺组织Fas蛋白和Fasl mRNA的表达;采用ELISA法测定肺组织肿瘤坏死因子α及白细胞介素1β水平。结果与结论:①与模型组比较,在依托咪酯后处理组中血氧分压升高(P<0.05),凋亡指数、肺湿/干质量比、Fas和Fasl mRNA表达、肿瘤坏死因子α及白细胞介素1β蛋白表达下降,凋亡坏死的病灶数量减少(P<0.05);②与依托咪酯后处理组比较,在不同剂量地塞米松的3组中,地塞米松0.5 mg/kg组的上述各指标改变均无显著性差异(P>0.05);③上述结果证实,依托咪酯后处理可降低大鼠肢体缺血再灌注导致的肺损伤,其机制可能与下调Fas/Fasl有关;在统计学角度上,依托咪酯1.0 mg/kg降低肺损伤的效价强度,几乎相当于地塞米松0.5 mg/kg。

BACKGROUND:To date,it has been confirmed that etomidate pre-treatment can reduce the damage of remote organs caused by limb ischemia-reperfusion,but whether etomidate post-treatment has protective effect on remote organs and its mechanism has been rarely reported.OBJECTIVE:To investigate the influence of etomidate post-treatment on limb ischemia-reperfusion lung injury.METHODS:A rat model of limb ischemia-reperfusion lung injury was prepared by clamping the bilateral femoral arteries for 2 hours and reperfusion for 3 hours.After 2 hours of limb ischemia,I/R group experienced the process of limb ischemia-reperfusion;I/R+ETO group,I/R+Dex 0.2 group,I/R+Dex 0.5 group and I/R+Dex 1.0 group,besides the model of limb ischemia-reperfusion,were injected with etomidate 1.0 mg/kg and dexamethasone 0.2,0.5 and 1.0 mg/kg respectively through tail vein.At 3 hours of reperfusion,blood samples were extracted from the carotid artery,blood gas analysis was performed and the partial pressure of blood oxygen(PaO2)was recorded.The pathological changes were detected by immunohistochemistry.Apoptotic index was detected by Hoechst 33258 staining and wet/dry weight ratio was detected.Fas protein and Fasl mRNA of lung tissue were detected by western blot and RT-PCR respectively.Tumor necrosis factor-αand interleukin-1βlevels were detected by ELISA.RESULTS AND CONCLUSION:Compared with the I/R group,PaO2 increased(P<0.05),Apoptotic index,wet/dry weight ratio,Fas and FasL mRNA,tumor necrosis factor-αand interleukin-1βdecreased in the I/R+ETO group,and the number of apoptotic lesions decreased in the I/R+ETO group(P<0.05).Compared with the I/R+ETO group,the change of each index was not statistically significant in the I/R+Dex 0.5 group(P>0.05).To conclude,etomidate post-treatment can reduce lung injury caused by limb ischemia-reperfusion in rats,and its mechanism may be related to the down-regulation of Fas/FasL.In the statistical point of view,etomidate 1.0 mg/kg has the potency intensity of reducing lung injury,almost equivalent to dexamethasone 0.5 mg/kg.