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目的:探讨缺血预处理保护脊髓神经的具体机制。方法 :50只成年SD大鼠随机分为假手术组(A组5只)、缺血再灌注组(B组20只)、缺血预处理组(C组5只)、缺血预处理+缺血再灌注组(D组20只)。A组动物麻醉后仅切开腹腔后关腹;B组和D组采用左肾下方0.5 cm处腹主动脉夹闭法夹闭0.5 h后松开,再灌注3、6、12、24 h,其中D组在缺血再灌注损伤前行缺血5 min、再灌注5 min缺血预处理,共3次;C组仅行3次缺血预处理。造模成功后,利用HE染色和免疫组化评估各组神经元的存活率,透射电镜观察自噬活性,免疫组化和蛋白印迹分析自噬标志物LC3-Ⅱ和自噬相关蛋白Beclin-1的表达情况。结果:缺血再灌注组中,LC3-Ⅱ蛋白在再灌注3 h后显著升高达到峰值后明显下降,24 h后几乎无表达;Beclin-1蛋白于再灌注后3 h开始升高且在24 h达到峰值;再灌注24 h后实验动物表现出明显的脊髓损伤症状,脊髓神经细胞存活率明显降低。缺血预处理+缺血再灌注组中,LC3-Ⅱ蛋白表达从再灌注3 h开始升高并持续至再灌注24 h;Beclin-1蛋白在再灌注24 h后才开始升高;与缺血再灌注组相比,缺血预处理+缺血再灌注组脊髓神经元死亡率明显降低。结论:缺血预处理通过维持缺血再灌注后神经细胞自噬水平并抑制自噬性细胞死亡从而保护脊髓神经细胞。
Objective: To investigate the specific mechanism of ischemic preconditioning for the protection of spinal nerves. Methods: Fifty adult Sprague-Dawley rats were randomly divided into 5 groups: sham operation group, ischemia reperfusion group (20 rats in group B), ischemic preconditioning group (5 rats in group C), ischemic preconditioning group Ischemia-reperfusion group (20 rats in group D). After anesthesia in group A, only the abdominal cavity was closed and the abdomen was closed; in group B and group D, 0.5 cm occlusion of the abdominal aorta at 0.5 cm below the left kidney was released for 0.5 h, then reperfused for 3, 6, 12 and 24 h, In group D, ischemic preconditioning was performed 5 min before ischemia-reperfusion injury and 3 min after ischemia reperfusion. Group C received ischemic preconditioning only 3 times. After successful modeling, the survival rate of neurons in each group was evaluated by HE staining and immunohistochemistry. The autophagy activity was observed by transmission electron microscopy. The expression of autophagy marker LC3-Ⅱ and autophagy-related protein Beclin-1 The expression of the situation. Results: In ischemia / reperfusion group, the expression of LC3-Ⅱprotein significantly increased at 3 h after reperfusion and then decreased significantly after 24 h, while Beclin-1 protein increased at 3 h after reperfusion 24 hours after reperfusion, the experimental animals showed obvious symptoms of spinal cord injury, and the survival rate of spinal cord neurons decreased significantly. In ischemic preconditioning + ischemia-reperfusion group, the expression of LC3-Ⅱ protein increased from 3 h after reperfusion to 24 h after reperfusion; Beclin-1 protein began to increase 24 h after reperfusion; Compared with the blood reperfusion group, the neuronal death rate of spinal cord in ischemic preconditioning + ischemia-reperfusion group was significantly decreased. CONCLUSION: Ischemic preconditioning protects the spinal cord neurons by maintaining autophagy level and inhibiting autophagic cell death after ischemia / reperfusion.