应激性溃疡大鼠胃黏膜中核因子κB信号通路的活化情况

Activation of nuclear factor-KB signaling pathway in rat gastric mucosa during stress ulceration

目的观察核因子κB(NF-κB)信号通路在应激性溃疡大鼠胃黏膜中的活化情况。方法采用浸水-束缚应激的方法制作大鼠应激性溃疡模型。应激前(0min)及应激5-360 min过程中设不同时相点处死大鼠,共9组,每组5只。采用凝胶电泳迁移分析(EMSA)法检测大鼠胃黏膜NF-κB与DNA的结合活性,蛋白质印迹(Western blot)法检测胃黏膜核因子抑制蛋白(hoBs)降解水平,RNA印迹杂交(Northern blot)法检测胃黏膜NF-κB下游效应分子肿瘤坏死因子(TNF)α、白细胞介素(IL)1β、细胞因子诱导中性粒细胞化学趋化因子(CINC)1、细胞间黏附分子(ICAM)1和诱导型一氧化氮合酶(iNOS)mRNA的表达水平。结果应激处理15 min内可见大鼠胃黏膜NF-κB迅速呈双相模式活化,其峰值出现于应激45 min和360 min,分别为应激前正常水平的(10．6±1．3)倍和(8．9±1．2)倍(P<0.01);抗体supershift实验结果表明,活化的NF-κB主要为p50／p65异二聚体。NF-κB活化第1相和第2相分别伴有明显的IκBα和IκBβ降解。应激15-30 min时TNF-α、IL-1β、CINC-1和ICAM-1基因转录明显上调,iNOS基因上调发生在应激30-90 min时,应激360 min时这些基因表达仍持续增加。结论NF-κB信号通路活化发生于浸水-束缚应激大鼠应激早期的胃黏膜中,可能在胃黏膜促炎性基因的过度表达中发挥了重要作用。

Objective To investigate the time course of nuclear factor-κB （NF-κB） activation in the process of stress ulcer formation. Methods Model of stress ulcer was reproduced by subjecting male Sprague-Dawley rats to water-immersion restraint （WIR） stress. At indicated time after the beginning of WIR stress, animals were sacrificed and cytoplasmic and nuclear protein and total RNA were prepared from gastric corpus mucosal tissues. DNA-binding activity of NF-κB was assessed as an index of NF-κB activation with electrophoretic mobility shift assay. Degradation of IκBα and IκBβ , the inhibitory proteins of NF-κB, was analyzed by Western blot analysis. Expression of NF-κB dependent genes including tumor necrosis factor-α （TNF-α）, interleukin-1β （ IL-1β）, cytokine-inducible neutrophil chemoattractant-1 （ CINC-1 ）, intercellular adhesion molecule-1 （ICAM-1） , and inducible nitric oxide synthase （iNOS） was detected with Northern blot analysis. Results WIR stress induced a rapid biphasic activation of gastric mucosal NF-κB within 15 min of the beginning of stress, peaking at 45 min and 360 min. Compared with baseline, NF-κB activation by stress was increased （10.6±1.3） and （8.9± 1.2） fold at 45 min and 360 min, respectively （ P 〈 0. 01 ）. Antibody supershift assays revealed that pSO/p65 heterodimer was the major active component of mucosal NF-κB. Western blot analysis showed that degradation of IκBα and IκBβ occurred at first and second wave of NF-κB activation. Corresponding with the rapid and persistent activation of NF-κB, the levels of TNF-α, IL-1β, CINC-1 and ICAM-1 mRNA in gastric mucosa were markedly increased 15 to 30 min after stress, respectively. Up-regulation of iNOS mRNAs was observed 30 to 90 min after stress, and the expression of all of these genes was increased consistently until the end of stress. Conclusion NF-κB activation is an early event and may play an important role in proinflammatory gene over-expression in rat gastric mucosa during WIR stress.