p38 MAPK/AP-1信号通路在1,2-二氯乙烷中毒性脑水肿形成中对iNOS表达的上调作用

Up-regulation effect of p38 MAPK/AP-1 signaling pathway on iNOS expression during formation process of toxic brain edema by 1,2-dichloroethane

目的探究p38 MAPK/AP-1信号通路在小鼠1?2-二氯乙烷(1?2-DCE)中毒性脑水肿形成过程中对诱导型一氧化氮合酶(iNOS)表达的作用及其对脑水肿的影响。方法选取40只雌性昆明种小鼠随机分为对照组、染毒组、低剂量以及高剂量p38抑制剂组。染毒小鼠于染毒柜中1.2 mg/L 1?2-二氯乙烷染毒3.5 h/d,连续染毒3 d,低、高剂量抑制剂组小鼠于染毒前1 h腹腔注射200μl 3.75、15 mg/kg的p38 MAPK抑制剂(SB202190)。染毒结束次日取材,测定各组小鼠脑含水量及HE病理观察脑水肿,Western Blot检测各组小鼠脑组织中磷酸化p38、激活蛋白1(AP-1)两个亚基c-fos、c-jun的磷酸化形式表达水平以及iNOS的蛋白表达,Real-Time RT-PCR检测iNOS mRNA表达水平。结果单纯染毒组的小鼠出现抱爪现象,SB202190干预能够明显改善1?2-DCE中毒小鼠的抱爪症状。染毒组小鼠脑组织含水量与对照组小鼠相比明显增加,SB202190干预能够有效缓解小鼠出现脑水肿。单纯染毒组小鼠脑组织中p-p38蛋白、磷酸化c-jun和c-fos表达水平明显上调,iNOS蛋白和mRNA表达水平也显著增加,而SB202190能够显著降低iNOS、磷酸化c-jun和c-fos的表达水平。结论小鼠脑组织iNOS mRNA和蛋白表达水平在1?2-DCE中毒性脑水肿形成过程中显著上调。p38 MAPK/AP-1信号通路参与iNOS表达增多的调控过程。

Objective To investigate the effect of p38 MAPK/AP-1 signaling pathway on the expression of inducible nitric oxide synthase(iNOS)during the formation process of toxic cerebral edema by 1,2-dichloroethane(1,2-DCE)in mice,and its effect on cerebral edema.Methods Forty female Kunming mice were randomly divided into four groups:control group,1,2-DCE exposed group,low dose p38 inhibitor group and high dose p38 inhibitor group;the exposed mice were inhaled with 1.2 mg/L of 1,2-DCE 3.5 h a day for 3 consecutive days and the mice in inhibitor group were intraperitoneally injected with 3.75 mg/kg(low dose)or 15 mg/kg(high dose)of SB202190(p38 MAPK inhibitor)1 h before 1,2-DCE exposure.The day after the end of 1,2-DCE exposure,the mice were killed,detecting the brain water content and the pathological change of brain edema,meanwhile,Western blot was used to detect the expressions of phosphorylated p38,phosphorylation forms of activator protein-1(AP-1)subunits c-fos and c-jun and iNOS protein in brains of mice in each group;the real-time RT-PCR was also used to detect the expression of iNOS mRNA.Results The results showed that there were some claw-holding phenomenon in the mice of 1,2-DCE exposed group,which would be well improved by SB202190,and the brain water content also got significantly alleviated.The expression levels of p-p38 protein,phosphorylated forms of c-jun and c-fos,iNOS protein and mRNA were all significantly up-regulated in brains of 1,2-DCE exposed mice,while SB202190 could significantly reduce the levels of iNOS and phosphorylated c-jun and c-fos.Conclusion The results suggested that expressions of iNOS protein and mRNA were up-regulated during the formation process of toxic cerebral edema by 1,2-DCE in mice,and p38 MAPK/AP-1 signaling pathway involved in the regulation of elevated expression of iNOS.