内毒素对心肌组织核因子-κB活化的影响及其意义

Effects of endotoxin on the activation of nuclear factor-kappaB in myocardium and its significance

目的通过观察内毒素(LPS)攻击大鼠心肌组织核因子-κB(NF-κB)的活化情况,探讨心肌损伤的可能信号机制。方法大鼠腹腔注射5mg/kgLPS制作脓毒症模型,采用凝胶阻滞迁移分析法(EMSA)检测心肌组织NF-κB活化情况,RT-PCR法检测TNF-α基因表达情况。结果LPS攻击后1h,NF-κB活化及TNF-α基因表达开始升高,2h达高峰,6h后逐渐下降。相关分析表明,心肌组织NF-κB活化与TNF-α基因表达呈显著正相关(r=0.9922,P<0.05)。结论LPS可增强心肌组织NF-κB的活化并诱导TNF-α基因表达。NF-κB活化导致的TNF-α合成增加在LPS介导心肌损害的分子机制中可能具有重要作用。

Objective To investigate the effects of endotoxin on the activation of nuclear factor-kappaB in myocardium, and to explore the molecular mechanism of acute myocardial injury. Methods Forty male Wistar rats were randomly divided into normal control group （n=10）, lipopolysaccharide （LPS） lh, 2h, 6h groups （n=10 for each group）. In the latter two groups, LPS was injected into the peritoneal cavity. Tissue samples from the myocardium were collected to determine NF-κB activation by electrophoretic mobility shift assay （EMSA）, and the mRNA expression of TNF-α was measured by semi-quantitative reverse transcription polymerase chain reaction （RT- PCR） with GAPDH as internal standard. Results The activation of NF-κB （2. 173± 0. 063） and TNF-α mRNA expression （0. 292± 0. 031） could be detected in myocardium in very low values in normal control group rats, while both the activation and expression were upregulated markedly after LPS challenge, and peaked 2 hours afterwards （37. 793±4. 785 and 1. 182±0. 146, respectively）. They were down-regulated （17. 910±3. 791 and 0. 901±0. 128, respectively） 6 hours after LPS challenge. Compared to normal controls, both NF-κB activity and TNF-α mRNA expression were significantly elevated at various time points following LPS stimulation （all P〈0. 01）. The activity of NF-κB was positively correlated with TNF-α mRNA expression level in myocardium （r=0. 992 2, P〈0. 05）. Conclusions LPS could lead to up-regulation of NF-κB activation in myocardium. The activation of NF-κB results in TNF-α mRNA expression and release. NF-κB signal pathway might play a critical role in the molecular mechanism of LPS induced myocardial injury.