运动预处理对脑缺血再灌注大鼠脑缺血区VEGF/VEGFR2/Dock6信号通路的影响

关键词：缺血再灌注  运动预处理  血管新生  血管内皮生长因子  血管内皮生长因子受体-2  细胞分裂蛋白6

Keywords:ischemia-reperfusion  exercise preconditioning  angiogenesis  vascular endothelial growth factor  vascular endothelial growth factor receptors  dedicator of cytokinesis 6

摘要：

      摘要 目的：从VEGF/VEGFR2/Dock6信号途径探索运动预处理对脑缺血再灌注损伤大鼠缺血侧脑组织血管新生的影响。 方法：采用随机数字表法将SD雄性大鼠分为假手术组、模型组和运动预处理组，每组18只。造模前，假手术组与模型组不给予任何处理，运动预处理组大鼠给予适应性跑步训练3d，电动跑台坡度为0°，速度10m/min，每天1次，每次20min。适应性训练结束后，运动预处理组给予为期3周的正式跑步训练，每周连续训练6d，休息1d，电动跑台坡度为0°，速度15m/min，30min/d。模型组和运动预处理组采用Koizumi栓线法加以改良制备大鼠大脑中动脉栓塞（MCAO）模型，假手术组仅切开皮肤，不插栓线。采用Zea-Longa评分和改良神经严重程度评分（mNSS）法进行神经功能缺损评估；TTC染色法检测脑梗死体积百分比，HE染色观察缺血侧大脑皮质组织形态学改变；免疫组化法观察缺血侧大脑皮质CD31表达水平；蛋白质免疫印迹测定VEGFA、VEGFR2、Dock6蛋白表达水平。 结果：①Zea-Longa评分：再灌注麻醉清醒后，与假手术组相比，其余2组大鼠Zea-Longa评分均增高（P<0.01），且2组间Zea-Longa评分无显著性意义；再灌注72h后，与假手术组相比，模型组大鼠Zea-Longa评分显著增高（P<0.01）；与模型组相比，运动预处理组大鼠Zea-Longa评分显著降低（P<0.05）。②mNSS评分：再灌注72h后，与假手术组相比，模型组大鼠mNSS评分显著增高（P<0.01）；与模型组相比，运动预处理组大鼠mNSS评分显著降低。③TTC染色：与假手术相比，模型组脑梗死体积百分比增大（P<0.01）；与模型组相比，运动预处理组脑梗死体积百分比相对减小（P<0.05）。④HE染色：与假手术组相比，模型组大鼠缺血侧大脑皮质出现显著病理学改变；与模型组相比，运动预处理组大鼠缺血侧大脑皮质病理学改变减轻。⑤CD31免疫组化：与假手术组相比，模型组大鼠缺血侧大脑皮质中CD31（P<0.01）显著升高；与模型组相比，运动预处理组大鼠缺血侧大脑皮质中CD31（P<0.01）进一步升高。⑥VEGF、VEGFR2、Dock6蛋白质免疫印迹：与假手术组相比，模型组大鼠缺血侧大脑皮质VEGF（P<0.05）、VEGFR2（P<0.05）、Dock6（P<0.01）蛋白表达含量升高；与模型组相比，运动预处理组大鼠缺血侧大脑皮质中VEGF（P<0.05）、VEGFR2（P<0.05）、Dock6（P<0.01）蛋白表达含量进一步升高。 结论：运动预处理可有效促进脑缺血后血管新生，减轻脑缺血再灌注以后的神经功能缺损表现，这一作用可能与其激活VEGF/VEGFR2/Dock6信号途径有关。

Abstract:

      Abstract Objective： To investigate the effect of exercise preconditioning on angiogenesis in ischemic brain tissue in rats with cerebral ischemia-reperfusion injury in the view of VEGF/VEGFR2/dock6 signaling pathway. Method： SD male rats were divided into sham group， model group and exercise preconditioning group by random number table method， with 18 rats in each group. The sham operation group and the model group were not given any treatment， while the exercise preconditioning group was given adaptive running training for 3 days at a speed of 10 m/min， once a day for 20 minutes each time. After the adaptive training， the exercise preconditioning group was given formal running training for 3 weeks， continuous training for 6 days a week， rest for 1 day， electric treadmill slope of 0°， speed of 15m/min， 30min/d. Model group and exercise preconditioning group were modified to prepare the middle cerebal artery occlusion （MACO） models by Koizumi thread method， while sham operation group only given skin cutting without thread insertion. Zea longa score and modified neurological severity score （mNSS） were used to score neurological deficit in rats， the relative infarct size of the brain was detected by TTC staining，the morphological changes of the ischemic cerebral cortex was observed by HE staining, the expression of CD31 in ischemic cerebral cortex was detected by immunohistochemistry and the expressions of VEGFA， VEGFR2， Dock6 in ischemic cerebral cortex were detected by western blot. Result： ①Zea-Longa scoring： after awaking from anesthetizati， compared with the sham group， the Zea-Longa scores of the other two groups were increased （P<0.01）， and there was no statistical significance in the Zea-Longa scores between the two groups. At 72 hours after reperfusion， compared with the sham group， the Zea-Longa score of the rats in the model group was significantly increased （P<0.01）； compared with the model group， the Zea-Longa score of the rats in the exercise preconditioning group was significantly decreased （P<0.05）. ②mNSS scoring： At 72 hours after reperfusion， compared with the sham group， the mNSS score of the rats in the model group was significantly increased （P<0.01）； compared with the model group， the mNSS score of the rats in the exercise preconditioning group was significantly decreased （P<0.05）.③TTC staining： Compared with the sham group， the cerebral infarction volume in the model group was increased （P<0.01）， and compared with the model group， the cerebral infarction volume in the exercise preconditioning group was decreased （P<0.05）. ④ HE staining： Compared with the sham group， the model group rats appeared significant pathological changes in the cerebral cortex on the ischemic side. Compared with the model group， the pathological changes of the cerebral cortex on the ischemic side of the rats in the exercise preconditioning group were alleviated. ⑤ Immunohistochemistry of CD31： Compared with the sham group， the expression of CD31 in the ischemic cerebral cortex of the model group was significantly increased（P<0.05）. The expression of CD31 in the ischemic cerebral cortex of the exercise preconditioning group was further increased（P<0.05）. ⑥Western blot of VEGF， VEGFR2 and Dock6： Compared with the sham group， the expressions of VEGF（P<0.05）， VEGFR2（P<0.05） and Dock6（P<0.01）in the ischemic cerebral cortex of the model group were significantly increased； compared with the model group， the expressions of VEGF（P<0.05）， VEGFR2（P<0.05） and Dock6（P<0.01） in the ischemic cerebral cortex of the exercise preconditioning group were further increased. Conclusion： Exercise preconditioning can effectively promote angiogenesis after cerebral ischemia and reduce cerebral ischemia-reperfusion injury， which may be related to the activation of VEGF/VEGFR2/Dock6 signaling pathway.