L-精氨酸对脂多糖诱导大鼠肺损伤的保护作用及其机制的研究

Effect of L-Arg on inflammatory reaction and nuclear factor-κ B signal pathway in the acute lung injury in rats induced by lipopolysaccaride

目的:观察一氧化氮供体L-精氨酸(L-Arg)对脂多糖诱导大鼠肺损伤炎症反应和核因子-κB(NF-κB)信号通路的影响,探讨L-Arg对肺损伤的保护作用及其机制。方法:健康雄性SD大鼠采用舌下静脉注射脂多糖(LPS)复制肺损伤模型,分别于给予LPS3h和6h后给予生理盐水(对照组及LPS组,ip)和L-Arg(500mg/kgip)(L-Arg治疗组),治疗3h。每组8只动物。免疫组化染色分析肺组织中NF-κB的核移位;逆转录多聚酶链反应(RT-PCR)检测肺组织细胞间粘附分子-1(ICAM-1)基因表达;放射免疫法分别测定肺组织中肿瘤坏死因子α(TNF-α)和白介素6(IL-6)的含量;光镜观察肺组织病理变化。结果:与对照组比较,大鼠肺损伤后NF-κB活化,明显从细胞浆移位于细胞核,表达量也显著增加;ICAM-1基因表达上调;肺组织中TNF-α、IL-6含量明显升高。肺损伤3h用L-Arg治疗3h后,NF-κB从细胞浆向细胞核的移位被明显限制,NF-κB的表达量、肺组织中TNF-α、IL-6含量明显低于相应的LPS组,肺组织病理改变减轻;肺损伤6h用L-Arg治疗3h对LPS引起的以上变化没有明显影响。结论:LPS3h后给予L-Arg可减轻内毒素性肺损伤,抑制核因子的活化,在一定程度上阻断NF-κB相关信号通路的传导,减轻炎症反应是其机制之一。

Objective：To investigate the effects and the mechanisms of L-Arginine（L-Arg）,the critical substrate for nitric oxide（NO）production,on pulmonary inflammatory cytokine expression and Nuclear Factor-κ B signal pathway in a model of lipopolysaccharide （LPS） induced acute lung injury（ALI）.Methods：Model of ALI was induced by injection（iv） with LPS 5 mg/kg in male SD rats.L-Arg （500 mg/kg ip） was administrated at 3 h or 6 h after LPS injection respectively for 3 h,and the rats were killed at 6 h or 9 h after saline （control） or LPS injection.The expression and the translocation of NF-κ B P65 in lung tissue were detected with immunohistochemisty（IHC）.The gene expression of intercellular adhesion molecule-1（ICAM-1） was examined by RT-PCR.The concentrations of TNF-α and IL-6 in lung tissue were respectively evaluated by radioimmunoassay.The pathological changes of lung tissue were observed by light microscope.Results：Compared with LPS group,treatment with L-Arg at 3 h after LPS significantly decreased the expression of NF-κ B protein.The concentrations of TNF-α and IL-6 in lung tissue were significantly decreased and the lung damage was inproved respectively compared with that of the LPS（3 h＋3 h） group.The lung damage was alleviated in L-Arg（3 h＋3 h） group.Conclusion：Relatively early administration of L-Arg might protect lung from LPS-induced injury by inhibiting NF-κ B activation and subsequently inhibiting the NF-κ B-mediated release of inflammatory factors.