脑缺血预处理对小鼠脑缺血再灌注损伤的保护作用

目的 研究脑缺血预处理对脑缺血再灌注损伤的保护作用。方法 C57BL/6 小鼠分4组,无缺血对照组行假手术,预处理对照组夹闭双侧颈总动脉6min,缺血组夹闭双侧颈总动脉18min,预处理组经6min缺血预处理后48h再行18min脑缺血。末次缺血后3d使用TUNEL原位标记法检测海马区神经原的DNA断片化改变,末次缺血后7d,用甲酚紫染色及微小管相关蛋白2免疫组化染色法观察海马区神经元损伤。结果 6min脑缺血未导致海马神经元缺失,18min脑缺血造成双侧海马神经元大量缺失,6min预处理明显减轻18min脑缺血所造成的神经元损伤及凋亡。结论 脑缺血预处理对脑缺血再灌注损伤有保护作用,此预处理模型为在基因水平研究脑缺血预处理保护作用的分子机制提供了一种新的手段。

Experimental study on the protective effects of ischemic preconditioning on brain ischemia-reperfusion in jury in mice

Objective To develop a forebrain ischemic preconditioning model in C57BL/6 mice and determine the protective effects of ischemic preconditioning on brain ischemia-reperfusion injury. Methods Forty-eight 8-10 week old C57BL/6 mice weighing 19-23 g were randomly divided into four groups of 12 animals, A: sham-operation group; B: ischemic preconditioning group; C: ischemia-reperfusion group (I/ R); D: ischemic preconditioning + I/R group. The animals were anesthetized with halothane. Bilateral common carotid artery (BCCA) was exposed and occluded for 6min (ischemic preconditioning) or 18min followed by 3h reperfusion (I/R). In group D BCCA was firstly occluded for 6 min, then released and 48h later occluded again for 18min followed by 3h reperfusion. 6 animals in each group were sacrificed 72h after reperfusion and brain was immediately removed for detection of DNA fragmentation of neurons in hippocampus by TUNEL. Another 6 animals were sacrificed on the 7th day after I/R and neuronal damage was identified by microtubule-associated protein-2 immunochemistry and quantified by cresyl violet staining. Results I/R resulted in severe damage to hippocampus in C57BL/6 mice. The ischemic preconditioning caused neither noticeable hippocampal neuronal damage nor DNA fragmentation but significantly reduced hippocampal neuronal damage and DNA fragmentation caused by I/R. Conclusion Our results indicate that hippocampal neuronal injury induced by I/R can be greatly reduced by ischemic preconditioning in C57BL/6 mice. Many kinds of gene-altered C57BL/6 mice are available, this preconditioning model may provide an useful method for investigating the molecular mechanisms of ischemic preconditioning.