3-甲基腺嘌呤预处理对大鼠多发性创伤后急性肺损伤的保护作用

Protective effects of 3-methyladenine on acute lung injury caused by multiple trauma in rats

目的：通过3-甲基腺嘌呤（3-methyladenine,3-MA）对多发性创伤模型大鼠进行预处理,探讨自噬在多发性创伤后急性肺损伤中的作用。方法：4月龄成年雄性SD大鼠45只,体重250～300 g,按照随机数字表随机分为3组：假手术组,对照组及3-MA组。假手术组仅在颅骨相应位置钻孔;3-MA组及对照组均采用液压打击器及自制骨折打击器制备股骨干骨折合并脑损伤模型,且分别于造模前1 h 给予10 mg/kg的3-MA或等量生理盐水。各组大鼠于术后48 h分别采用实时荧光定量PCR检测肺部LC-3Ⅱ及Beclin-1的表达;ELISA法检测肺部炎症因子TNF-α、IL-6的浓度;HE染色观察肺部的组织病理学改变。结果：术后48 h,对照组大鼠肺部LC-3Ⅱ及Beclin-1的mRNA水平明显高于假手术组（P〈0.01）,而3-MA组上述基因的表达显着低于对照组（P〈0.01）;术后48 h,对照组大鼠肺部的TNF-α及IL-6浓度明显高于假手术组,3-MA组上述因子的浓度显着低于对照组（P〈0.01）.3-MA组大鼠肺组织病理评分显着低于对照组（P〈0.01）.3-MA组大鼠肺组织病理评分显着低于对照组（P〈0.01）.结论：自噬可以加重股骨干骨折合并脑损伤后的急性肺损伤,而采用其抑制剂3-MA进行预处理可以降低细胞自噬水平,进而减轻肺部的损害。

Objective：To investigate the role of autophagy in acute lung injury（ALI） caused by multiple trauma in rats via pretreat with 3-methyladenine （3-MA）. Methods：Forty-five Sprague-Dawley male rats, with age of 4 months and body weight of 250-300 g, were randomly divided into three groups. In the sham group, the rats received sphenotresia only;in the control group, the rats were made model of femur shaft fracture combined with brain injury, and treated with physiological saline by abdominal cavity at 1 hour before making model;in the 3-MA group, the rats were made model of femur shaft fracture combined with brain injury, and treated with 3-MA of 10 mg/kg by abdominal cavity at 1 hour before making model. Histologic changes and the concentration of related inflammatory factors in the damaged lung tissue were examined at 48 h after opteration, at the same time, the effect of 3-MA on the expression of LC-3Ⅱand Beclin-1 was examined through reverse transcriptase polymerase chain reaction technique （RT-PCR）. Results：Compared with sham group, LC-3Ⅱand Beclin-1 level in control group at 48 h after operation were obviously increased（P〈0.01）. Compared with control group, LC-3Ⅱand Beclin-1 level in 3-MA group at 48 h after operation were obviously decreased（P〈0.01）. Compared with sham group, the level of proinflammatory cytokines （TNF-α and IL-6） in control group obviously enhanced （P〈0.01）. Compared with control group, above items in 3-MA group was obviously lower（P〈0.01）. Compared with control group, the histopathological damage of lung in 3-MA group obviously reduced（P〈0.01）. Conclusion：Autophagy can aggravate the acute lung injury caused by fracture of shaft of femur combined with brain injuries, but 3-MA can reduce tissue damage by inhibiting the autophagy and inflammatory response.