南方医科大学学报

南方医科大学学报 ›› 2020, Vol. 40 ›› Issue (04): 463-468.doi: 10.12122/j.issn.1673-4254.2020.04.03

• • 上一篇    下一篇

线粒体融合与裂变在右美托咪定减轻小鼠脑缺血再灌注损伤中的作用及其机制

刘 刚，门运政，童旭辉，王雪如，胡 淼，姜牧君，孙志鹏，董淑英   

  • 出版日期:2020-04-30 发布日期:2020-04-20
  • 基金资助:

Role of mitochondrial fusion and fission in protective effects of dexmedetomidine against cerebral ischemia/reperfusion injury in mice

  

  • Online:2020-04-30 Published:2020-04-20

HTML

PDF

1097

摘要： 目的 探讨右美托咪定（DEX）对小鼠脑缺血/再灌注（I/R）损伤的影响及线粒体融合与裂变在其中的作用。方法 将雄性ICR小鼠随机分为假手术（sham）组、缺血/再灌注（I/R）组、缺血/再灌注+右美托咪定（I/R+DEX）组、缺血/再灌注+右美托咪定+dorsomorphin（I/R+DEX+dorsomorphin）组。采用改良线栓法制备小鼠大脑中动脉栓塞模型，于缺血前30 min 腹腔注射DEX50 μg/kg，缺血1 h，再灌注24 h；采用Longa五分法对小鼠进行神经行为学评分；TTC染色法检测小鼠脑梗死体积，并计算脑梗死体积百分率；透射电镜法观察线粒体形态变化；免疫印迹法检测磷酸化AMP蛋白激酶、线粒体融合蛋白2、线粒体裂变相关蛋白的表达变化。结果 DEX 预处理降低了 I/R 组小鼠神经行为学评分和脑梗死体积百分率，在使用 DEX 的基础上加用dorsomorphin后，小鼠神经行为学评分和脑梗死体积百分率升高（P<0.01）；电镜结果显示，DEX减轻了缺血再灌注导致的线粒体损伤（P<0.01），线粒体形态有所恢复。免疫印迹检测结果显示，DEX预处理增加了磷酸化AMP蛋白激酶、线粒体融合蛋白2表达，降低了线粒体裂变相关蛋白表达，而加用dorsomorphin后，磷酸化AMP蛋白激酶、线粒体融合蛋白2表达明显降低，线粒体裂变相关蛋白表达显著增加（P<0.01）。结论 DEX预处理可以减轻I/R损伤，其机制可能与激活AMPK从而促进线粒体融合 及抑制线粒体裂变有关。

Abstract: Objective To investigate the protective effects of dexmedetomidine (DEX) against cerebral ischemia/reperfusion (I/R) injury in mice and its relation with mitochondrial fusion and fission. Methods Male ICR mice were randomly divided into sham- operated group, I/R group, I/R +DEX group and I/R +DEX +dorsomorphin group. Mouse models of cerebral I/R injury were established by modified thread occlusion of the middle cerebral artery. DEX (50 μg/kg) was injected intraperitoneally at 30 min before cerebral ischemia, which lasted for 1 h followed by reperfusion for 24 h. The neurobehavioral deficits of the mice were evaluated based on Longa’s scores. The volume of cerebral infarction was detected by TTC staining. The changes in mitochondrial morphology of the brain cells were observed with transmission electron microscopy. Western blotting was performed to detect the expressions of phosphorylated AMP-activated protein kinase (p-AMPK), mitochondrial fusion protein (Mfn2) and mitochondrial fission protein (p-Drp1) in the brain tissues. Results DEX pretreatment significantly reduced the neurobehavioral score and the percent volume of cerebral infarction in mice with cerebral I/R injury. Treatment with dorsomorphin (an AMPK inhibitor) in addition to DEX significantly increased the neurobehavioral score and the percent volume of cerebral infarction in the mouse models. Transmission electron microscopy showed that DEX obviously reduced mitochondrial damage caused by cerebral I/R injury and restored mitochondrial morphology of the brain cells, and such effects were abolished by dorsomorphin treatment. Western blotting showed that DEX pretreatment significantly increased the expressions of p-AMPK and Mfn2 protein and decreased the expression of p-Drp1 protein in the brain tissue of the mice, and these changes were also reversed by dorsomorphin treatment. Conclusion Preconditioning with DEX produces protective effects against cerebral I/R injury in mice possibly by activating AMPK signaling to regulate mitochondrial fusion and fission in the brain cells.