氨基胍对内毒素性肺损伤细胞凋亡的影响

目的观察选择性一氧化氮合酶抑制剂氨基胍(AG)对大鼠内毒素性肺损伤(ALI)细胞凋亡的影响,探讨AG对肺损伤组织的保护作用及其机制。方法健康♂SD大鼠,随机分为:①对照组;②模型组(LPS组);③AG治疗组。其中LPS组和AG治疗组按治疗时间又分为给LPS3h后治疗3h(3h+3h)组和给LPS6h后治疗3h(6h+3h)组,AG治疗组分别于给LPS3h和6h后给AG(100mg·kg-1),ip给药,LPS组给等量的生理盐水;(3h+3h)组于注射LPS6h后处死大鼠;(6h+3h)组于注射LPS9h后处死大鼠,每组8只动物。模型组、AG治疗组iv注射LPS复制内毒素性肺损伤大鼠模型,对照组给等量生理盐水。逆转录聚合酶链反应(RT-PCR)法测定肺组织中NOSmRNA表达变化;电镜、流式细胞术(FCM)检测肺细胞凋亡率;Westernblot法检测Caspase-3蛋白的表达;免疫组化法测定Bcl-2和Bax蛋白的表达;光镜、电镜观察肺组织病理变化。结果与对照组比较,大鼠肺损伤后,iNOSmRNA表达增强,eNOSmRNA表达减弱,nNOSmRNA表达没有明显变化;细胞凋亡率、Caspase3和Bax蛋白表达明显升高,Bcl-2蛋白表达下降,Bcl-2/Bax降低;肺损伤3h用AG治疗3h后,iNOSmRNA表达、细胞凋亡率、Caspase-3和Bax蛋白表达低于对照组,Bcl-2蛋白表达、Bcl-2/Bax高于对照组,肺组织病理改变减轻;肺损伤6h用AG治疗3h后,治疗效果较差。结论AG在较早时候给药可减轻内毒素性肺损伤,可能与减弱iNOSmRNA和Caspase-3表达、增强Bcl-2蛋白表达、减弱Bax蛋白表达、调节Bcl-2蛋白/Bax蛋白平衡有关。

Effect of aminoguanidine on pulmonary apoptosis in the lipopolysaccharide-induced acute lung injury in rats

Aim To investigate the effect and the possible mechanism of aminoguanidine (AG) on the lipopolysaccharide(LPS)-induced acute lung injury in rats. Methods Male SD rats were randomly divided into 3 groups: ① Control group; ② LPS group; ③ AG group. AG was administrated in AG group, saline was administrated in control group and LPS group. LPS group and AG group were further divided into 2 subgroups according to the duration of ALI:3 h+3 h group and 6 h+3 h group. In AG group and LPS group, LPS was administrated. Saline was administrated in control group. Expressions of NOS mRNA in the lung tissue were respectively measured with RT-PCR method;Apoptosis, the expression of Caspase-3 protein, Bcl-2 and bax were respectively detected with Flow Cytometry (FCM), Western blot analysis, and immunohistochemisty (IHC); the pathological changes of lung tissue were observed by light and electron microscope. Results Compared with that of the control group, the expression of iNOS mRNA was significantly increased; the eNOS mRNA was significantly decreased; apoptosis of pulmonary cells, the expression of Caspase-3 and Bax protein were significantly increased; the expression of Bcl-2 was decreased in alveolar and airway epithelial cells in LPS group respectively. Degree of ALI was gradually worsened after administration of LPS. In AG(3 h+3 h) group, the percentage of apoptotic cells, the expression of caspase-3 and Bax protein were decreased respectively, the expression of Bcl-2 and the ratio of Bcl-2 /Bax were increased and the lung damage was improved respectively compared with that of the LPS(3 h+3 h) group. Conclusion Relatively early administration of AG could ameliorate LPS-induced acute lung injury in rats. The possible mechanism is that AG could reduce the expression of iNOS mRNA,Caspase-3 and Bax protein,increase the expression of Bcl-2 protein, and regulate the balance between Bcl-2 and Bax protein.