不同缺血后处理对大脑中动脉闭塞/再灌注大鼠排斥导向分子a表达的影响

Effect of different ischemic postconditioning on infarct volume and expression of repulsive guidance molecule a in middle cerebral artery occlusion/reperfusion rat

目的观察几种不同的缺血后处理(IPC)方式对大鼠缺血再灌注(I/R)后神经损伤影响,为缺血性脑损伤的保护策略提供依据。方法 SD大鼠随机分为6组,分别为假手术组、大脑中动脉I/R模型组I/R、IPC(颈总动脉10 s×6次循环)(IPC-S组)、IPC(颈总动脉5 min×3次循环)(IPC-M组)、远隔IPC(股动脉5min×3次循环)(RIPC组)、延迟后处理(缺血24 h后颈总动脉5 min×3次循环)(DIPC组)。I/R 48 h用TTC染色测量脑梗死体积,RT-PCR检测缺血侧皮质及海马排斥导向分子a(RGMa)mRNA表达,免疫组织化学法检测缺血皮质及海马RGMa蛋白表达。结果 IPC-S、IPC-M、RIPC组相比I/R组脑梗死体积、RGMa mRNA和蛋白表达均有不同程度下降(P<0.05)。但DIPC组较模型组各相应指标变化不明显(P>0.05)。结论使用早期、近端、短暂的缺血后处理能减少大鼠脑缺血性损伤后梗死体积,缺血后处理的脑保护机制可能与降低RGMa这一轴突生长负性分子的表达有关。

Objective By investigating the impact of different ways of ischemic postconditioning on neural injury after ischemia reperfusion injury （ IRI）, to provide the evidence of protective strategy against ischemic brain injury. Methods Sprague-Dawley （SD） rats were randomly assigned into 6 groups as sham-operated group, ischemia/reperfusion （I/R） model group, ischemic postconditioning group （IPC-S, common carotid artery, 10 s x 6 cycles） , ischemic postconditioning group （IPC-M, common carotid artery, 5 minx 3 cycles）, remote postconditioning group （RIPC, femoral artery, 5 min× 3 cycles）, delayed ischemic postconditioning group （DIPC, common carotid artery, 5 min x3 cycles performed 24 h after ischemia）. After reperfusion with 48 h, the infarcted volume were measured by Trc stain meth- od, repulsive guidance molecule （RGM）a mRNA expression in the ischemic cortex and hippocampus were detected by RT-PCR, to detect RGMa protein expression by immunohistochemistry method. Results The infarct volume, RGMa mRNA and protein were reduced in IPC-S, IPC-M and RIPC group, the differentiation were significant compare with those of I/R group （P 〈 0. 05 ）. However, the values of DIPC group were not significantly different from those of I/R group （P 〉 0.05）. Conclusions Isehemic postconditioning performed on the early stage, proximal to the injury location and with short duration in each circle after reperfusion may reduce the ischemic damage to brain. The protective effect of ischemia postconditioning may be relevant to the expression of RGMa which is negative axonal growth molecule.