甲泼尼龙和纳洛酮对大鼠肺缺血/再灌注损伤的保护作用研究

目的 研究甲泼尼龙、纳洛酮在大鼠肺缺血/再灌注(I/R)损伤中的作用,并探讨其可能机制.方法 雄性SD大鼠70只,随机均分为假手术组(sham组)、I/R组、甲泼尼龙组(MP组)、纳洛酮组(Na组)、甲泼尼龙联合纳洛酮组(MP+Na组).术后3 h和6 h取标本,用钙结合蛋白Ⅴ-碘化丙啶(AnnexinⅤ-PI)双染法、流式细胞仪检测肺组织凋亡细胞并计算凋亡率;用免疫组化及图像分析法观察肺脏核转录因子-κB抑制因子-α(IκB-α)、天冬氨酸特异性半胱氨酸蛋白酶-3(caspase-3)的表达;计算肺湿/干重(W/D)比值;苏木素-伊红(HE)染色,光镜下观察肺组织病理学变化,电镜下观察肺脏超微结构的改变.结果 ①6 h MP组较I/R组肺脏IκB-α的表达有所增加,差异有统计学意义(P＜0.01);3 h和6 h Na组较I/R组肺组织caspase-3表达明显减少,差异有统计学意义(P均＜0.05);MP组和Na组3 h和6 h的细胞凋亡率较I/R组均有所减少(P均＜0.01),肺组织的病理形态及超微结构损害均有所减轻.②MP+Na组较MP组、Na组、I/R组肺组织凋亡率、caspase-3表达均有不同程度的减少(P＜0.05或P＜0.01),肺脏IκB-α的表达较6 h Na组显著增多(P＜0.05),肺组织的病理形态及超微结构损害明显减轻,6 h较3 h减轻更明显.结论 甲泼尼龙、纳洛酮分别通过抗炎、减少caspase-3的激活两个不同途径抑制凋亡的发生,早期联合应用有协同效应,更能有效抑制肺组织I/R损伤凋亡的发生,对肺组织有明显的保护作用.

Protective effect of methylprednisolone and Naloxone on pulmonary ischemia/reperfusion injury in rats

OBJECTIVE: To investigate the effect of methylprednisolone (MP) and naloxone (Na) on pulmonary ischemia/reperfusion (I/R) injury in rats and to study its possible mechanism. METHODS: Seventy male Sprague-Dawley (SD) rats were used for reproduction of unilateral lung ischemia/reperfusion (I/R) injury, and they were randomly divided into five groups (14 rats in each group): sham operation group (sham group), I/R group, MP group,Na group, and MP+Na group. Each group was subdivided into two subgroups of 3-hour and 6-hour postinjury. I/R injury was produced by 45 minutes of cross-clamping of the pulmonary artery, followed by 3 hours or 6 hours of reperfusion. Apoptosis rate in lung tissue was assessed by the use of Annexin-V-PI with flow cytometry. Expression of IKappaB-alpha and caspase-3 in lung tissue were observed by immunohistochemical stain and image analysis. The wet to dry weight (W/D) ratio, the pathological and ultrastructure changes in lung tissue were observed. RESULTS: (1) The expression of IKappaB-alpha in lung was obviously lower in I/R group than in 6-hour MP group (P<0.01), while expression of caspase-3 in lung tissue was significantly less intense in 3-hour and 6-hour Na group compared with I/R group (both P<0.05). Apoptosis rate in lung tissue was obviously lower in MP and 3-hour and 6-hour Na group than in I/R group (both P<0.01). The pathological and ultrastructure changes in lung tissue were less intensive. (2) Apoptosis rate, caspase-3 of lung tissue were significantly lower in MP+Na group than of 6-hour in MP, Na, I/R groups (P<0.05 or P<0.01) while the expression of IKappaB-alpha was higher than of 6-hour Na group. The pathological and ultrastructure change in lung tissue were less more mark in MP+Na group than in other groups. CONCLUSION: MP and Na inhibit apoptosis in lung I/R injury by either decreasing the activation of IKappaB-alpha or caspase-3.MP and Na when used together in early period of lung I/R injury could exert more effective protection to lung tissue.