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

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。

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

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.