严重烧伤大鼠肝脏p38丝裂原活化蛋白激酶对肿瘤坏死因子α表达的调控及其在肝损伤中的作用

The modulating role of p38 mitogen-activated protein kinase in the expression of tumor necrosis factor-α in hepatic cells and its role in hepatic injury in severely burned rats

目的观察大鼠严重烧伤后肝脏p38丝裂原活化蛋白激酶(MAPK)对肿瘤坏死因子(TNF)α表达的调控及其在肝损伤中的作用。方法将健康成年雄性SD大鼠随机分为假伤组;烧伤+SB203580组:30%TBSAⅢ度烫伤(以下称烧伤)后15min和12h静脉注射p38MAPK的特异性抑制剂SB203580(10mg/kg);烧伤对照组:同前致伤后给予等量等渗盐水,每组8只。测定3组大鼠伤后24h血清天冬氨酸转氨酶(AST)和丙氨酸转氨酶(ALT)活性的变化,并分别采用实时逆转录聚合酶链反应(RT-PCR)法和蛋白印迹(Western blot)法检测肝脏TNF-αmRNA及p38MAPK、磷酸化p38MAPK的表达水平。结果烧伤对照组大鼠血清AST和ALT活性及肝脏TNF-αmRNA的表达水平均显著高于假伤组(P<0.05或0.01);烧伤+SB203580组此3项指标均显著低于烧伤对照组(P<0.05或0.01),但与假伤组比较差异无统计学意义(P>0.05).3组大鼠肝脏p38MAPK表达水平比较,差异无统计学意义(P>0.05);其磷酸化p38MAPK表达水平之比———假伤组∶烧伤对照组∶烧伤+SB203580组为1.00∶3.90∶1.10,烧伤+SB203580组与假伤组比较,差异无统计学意义(P>0.05),与烧伤对照组比较明显偏低(P<0.01).结论大鼠严重烧伤后,肝脏中活化的p38MAPK促进了TNF-αmRNA的表达,并参与了肝损伤的发生。

Objective To investigate The modulating role of p38 mitogen-activated protein kinase （MAPK） in the expression of tumor necrosis factor-or in hepatic cells and its role in hepatic injury in severely burned rats. Methods Twenty-four adult healthy male SD rats were randomly divided into three groups （8 rats in each group） ： sham group, burn group, and burn with SB203580 group. A rat model of full-thickness burn injury covering 30% total body surface area （TBSA） was reproduced. The specific inhibitor of p38MAPK （SB203580 in 10 mg/kg） was given to the rats in the burn with SB203580 group at 15 minutes and 12 hours after burn. The serum levels of aspartate aminotransferase （AST） and alanine aminotransferase （ALT） were measured at 24 postburn hours （PBHs）. The TNF-α mRNA expression in the liver was determined by real-time reverse transcription polymerase chain reaction, and the expression levels of p38MAPK and phosphor-p38 MAPK in the liver were determined by Western blot analysis. Results The serum levels of AST and ALT, and the expression of TNF-α mRNA in liver cells were significantly higher in burn group than those in sham and SB203580 groups （ P 〈 0.05 or 0.01 ） , but there was no difference between the two latter groups. It was indicated by Western blot results that there was no difference of p38 MAPK expression in rat liver among the three groups （ P 〉 0.05）. The phospho-p38MAPK expression ratio among sham, burn and burn with SB203580 groups was 1.00： 3.90： 1.10. The phospho-p38MAPK expression was signifiantly lower in burn with SB203580 group than that in burn group（ P 〈0. 01 ） ,but there was no significant difference compared with that in sham group （P 〉 0. 05 ）. Conclusion The postburn activated p38MAPK in rat liver after severe burn injury enhances the expression of TNF-α mRNA and participates in the development of postburn hepatic injury.