丝裂原激活蛋白激酶在内毒素脂多糖诱导大鼠施万细胞一氧化氮合酶表达中的作用

目的 主要研究丝裂原激活蛋白激酶(MAPK)信号途径在内毒素脂多糖(LPS)诱导大鼠施万细胞(Scs)诱导型一氧化氮合酶(iNOS)基因表达和一氧化氮(NO)产生中的作用.方法 先用3种MAPK的特异性抑制剂PD98059(ERK1/2)、SB202190(P38 MAPK)和SP600125(JNK)以不同浓度预处理细胞1h,再用LPS作用施万细胞4 h后,用RT-PCR检测细胞中iNOS mRNA、IL-6 mRNA和TNF-α mRNA的表达;Western blotting观察iNOS蛋白水平的表达变化;通过测定细胞培养液中亚硝酸盐含量来观察NO的水平.结果 LPS可显著激活施万细胞中MAPK信号通路诱导iNOS表达.MAPK的抑制剂预处理细胞后,可显著抑制细胞iNOS mRNA和NO的合成及IL-6 mRNA和TNF-α mRNA的表达.结论 MAPK信号通路参与了LPS介导的大鼠施万细胞iNOS基因表达和NO产生,通过阻断细胞内信号转导通路来减少iNOS及其他细胞因子的产生,为抑制周围神经损伤后的炎症以及免疫反应发生提供了一条新思路.

THE ROLE OF MAPK IN LPS-INDUCED iNOS EXPRESSION IN RAT SCHWANN CELLS

Objective To explore the role of mitogen activated protein kinase(MAPK)in lipopolysaccharide(LPS) induced iNOS expression and NO production in rat Schwann cells by the use of inhibitors PD98059 selective for extracellular signal regulated kinase 1/2(EPK1/2), SB202190 for P38 MAPK and SP600125 for the c-Jun NHSUB>2/SUB>-terminal kinase (JNK). Methods Schwann cells were pretreated with PD98059 (30, 50, 70μmol/L), SB202190 (10, 20, 40μmol/L) and SP600125 (10, 30, 50μmol/L) at the indicated concentrations for 1 hour before the stimulation with LPS (10mg/L) for 4 hour. The estimation of iNOS mRNA, IL-6 mRNA and TNF-α mRNA was performed by RT-PCR; the changes of iNOS protein expression were investigated by Western blotting. The NO level was observed with measurement of nitrite in the cell culture medium. Results LPS could significantly activate MAPK signal pathway and lead to the expression of iNOS and NO production. The iNOS expression and NO production induced by LPS stimulation were significantly inhibited by the three highly specific inhibitors of MAPK. In addition, the inhibitors decreased LPS induced the expression of IL-6 mRNA and TNF-α mRNA. Conclusion Activation of MAPK pathway is involved in iNOS expression and NO production in rat Schwann cells, and the inhibition of the signal transduction pathway can be effective to reduce