皮层扩散性抑制预处理对大鼠脑缺血性损伤的保护作用

Experimental study of cortical spreading depression preconditioning protecting brain against cerebral ischemia injury in rats

目的研究KCI诱导皮层扩散性抑制(CSD)预处理对大鼠大脑中动脉阻塞后脑血流灌注和梗死体积的影响,验证CSD对脑缺血性损伤的保护作用。方法24只SD大鼠分为实验组和对照组,各12只,试验组用5 mol/L KCl大鼠大脑皮层诱发CSD,3d后插线法栓塞大脑中动脉制备大鼠局灶性脑缺血模型,利用激光散斑衬比光学成像技术监测缺血2h大脑血流动力学变化,并测定大脑梗死病灶体积。对照组用NaCI代替KCI,其余相同。比较血流动力学变化和大脑梗死灶体积的大小。结果经CSD预处理后3d再缺血时,实验组缺血病灶血液灌注水平高于对照组,实验组总梗死体积及皮层梗死体积均小于对照组,皮层下梗死体积与对照组差异无统计学意义(P＞0．05)。结论利用激光散斑衬比光学成像技术可以在体检测脑血流的变化,同时验证了CSD预处理可提高缺血病灶皮层的血液灌注水平,减少总梗死体积和皮层梗死体积,可以减轻脑缺血后的脑功能损害程度。

Objective To study the effects of KCl-induced cortical spreading depression （CSD） preconditioning on cerebral blood flow and infarct volume after middle cerebral artery occlusion （MCAO） in rats and the protective effects of CSD on brain ischemic injury. Methods Three days before the imposition of focal cerebral ischemia CSD was elicited by applying KCl for 2 h through a microdialysis probe implanted in the occipital cortex. Control animals were handled identically except that saline was infused instead of KCl. Focal ischemia was produced through the intraluminal suture method by MCAO. Opitcal imaging technology of laser speckle imaging was use to monitor the cerebral blood flow （CBF） during 2 h of ischemia period and cortical and subcortical infarct volumes were measured 7 days later. Results In CSD preconditioning group, CBF during MCAO was significantly improved and the hemispheric and neocortical volume of infarction induced as compared with control group. There was no difference between the two groups in the subcortical infarct volume. Conclusion Optical imaging technology of laser speckle imaging can be used to monitor the CBF in vivo. CSD preconditioning can improve the cortical CBF significantly and reduce the hemispheric and neocortical volume of infarction, so protect brain from ischemic injury.