c-Jun氨基末端激酶通路在内毒素休克大鼠生物喋呤诱生中的信号机制

The potential mechanisms of c-Jun amino-terminal kinase signal transduction pathway in biopterin induction in rats with endotoxic shock

目的 观察c Jun氨基末端激酶 (JNK)信号通路抑制剂———curcumin对内毒素休克大鼠生物喋呤 (BH4 )及一氧化氮 (NO)表达的影响 ,并探讨JNK途径在生物喋呤诱生中的信号转导机制。方法 建立内毒素休克模型 ,6 0只大鼠随机分为正常对照组 (n =8)、内毒素休克组 (n =32 )和curcumin拮抗组 (n=2 0 )。采用逆转录多聚酶链式反应测定肝、肺、肾组织三磷酸鸟苷环水解酶I (GTP CHI)与诱生型一氧化氮合酶 (iNOS)mRNA表达水平 ,分别采用反相高效液相色谱法和Griess比色法测定血浆与组织中BH4 、NO水平的变化。结果 与正常对照组相比 ,内毒素使动物肝、肺、肾组织GTP CHI基因表达和BH4水平明显升高 ,至伤后 2 4h仍持续于较高水平 ;与之相应 ,组织iNOS基因表达和NO水平亦明显升高。curcumin处理可明显下调肝、肺、肾组织GTP CHImRNA表达水平 ,并且肝组织 6～ 2 4h时、肺组织 12h时BH4 水平显著降低 ;各组织iNOSmRNA表达及NO水平亦显著降低。结论 抑制JNK信号通路能明显抑制内毒素休克鼠多器官生物喋呤 /NO系统的表达 ,JNK途径参与了生物喋呤诱生的信号转导过程。

Objective To investigate the effect of inhibitors of c-Jun amino-terminal kinase (JNK) signal transduction pathway on the expression of biopterin as well as nitric oxide (NO), and study the potential mechanism underlying biopterin induction in rats after endotoxic shock. Methods Using an endotoxic shock model, 60 male Wistar rats were randomly divided into normal control group (n=8), endotoxic shock group (n=32) and curcumin treatment group (JNK inhibitor, n=20). At serial time points animals in each group were sacrificed, and tissue samples from liver, lungs as well as kidneys were harvested. Guanosine triphosphate-cyclohydrolase (GTP-CHI) and inducible nitric oxide synthase (iNOS) mRNA expression in liver, lungs and kidneys were semi-quantitatively determined by reverse transcription polymerase chain reaction (RT-PCR). Biopterin and NO levels in blood and tissues were assayed by reverse phase high performance liquid chromatography (HPLC) with fluorescent detection and the Griess reaction, respectively.Results Compared with normal controls, GTP-CHI mRNA expression and biopterin levels were significantly elevated in various tissues, keeping at relatively high levels up to 24 h, so did the values of iNOS mRNA expression and NO levels after endotoxin challenge. Pretreatment with curcumin could down-regulate GTP-CHI mRNA expression in various tissues. Meanwhile, biopterin contents were markedly decreased in liver and lungs at 6 h～24 h and 12 h, respectively, so were the values of iNOS mRNA expression and NO in various tissues.Conclusion These data suggests that the inhibition of JNK markedly down-regulate the production of bioptefin/NO in rats subjected to endotoxic shock, and JNK pathway be involved in the signal transduction of biopterin induction after endotoxin challenge.