脑不对称性对大鼠局灶性脑缺血模型的梗死体积及行为功能的影响

The Effect of Cerebral Asymmetry on the Infarct Volume and Behavior Function of Focal Cerebral Ischemia in the Rats

目的探讨不同时间点应用线栓法制作不同侧别大脑中动脉闭塞(middle cerebral artery occlusion,MCAO)模型对大鼠神经功能和脑梗死体积的影响。方法参照Zea-Longa法制作大鼠局灶脑缺血模型,1.5 h后进行缺血再灌注(I/R)。36只SD大鼠随机分为经左、右侧插线组,并对两组大鼠I/R后不同时间点(1、3、7 d)的神经功能缺损评分、平衡木试验、水迷宫试验及脑梗死体积进行测定和比较。结果经左侧MCAO组大鼠的肢体运动平衡能力在I/R后1、3、7 d均显著低于右侧组,而记忆功能显著高于右侧组,以I/R后7 d差异更明显。两组脑梗死体积在I/R后3 d时最大,7 d时最小;在I/R后1 d及3 d时两组脑梗死体积无明显差异;而I/R后7 d时,左侧组梗死体积高于右侧组。结论栓塞左右侧对大鼠MCAO模型早期梗死体积影响不大,而后期左侧栓塞的梗死体积大于右侧。并且左侧半球梗死引起的运动功能损害更重,右侧半球梗死引起的记忆功能缺损更严重。提示大鼠左右脑半球可能存在结构和功能的不对称,从而影响局灶性脑缺血的结局。

Objective To investigate the effect of different side middle cerebral artery occlusion（MCAO）model at different time point on the infarct volume and neurological function in the rats by application of Zea-longa method.Methods Middle cerebral artery occlusion（MCAO） was induced in rats by filament insertion for1.5 h according to Zea-Longa method. A total of 36 Sprague-Dawley rats were randomly divided into left MCAO and right MCAO groups. Behavior scores, trapezoid balance bar experiment and Morris water maze experiment were all carried out to evaluate the recovery of neural function and infarct volume of the brains were measured at the 1st, 3rd, 7th day after operation respectively.Results Compared with the right MCAO group, the motor function, balancing function of the left MCAO group all decreased at the 1st, 3rd, 7th day after cerebral ischemia-reperfusion, however, memory function was obviously higher than that of right MCAO group, especially at 7th day after I/R. Total infarction volume was the largest at 3rd day after I/R, and smallest at 7th in the two groups. There was no significant difference in infarct volume of the two groups at the 1st and 3rd day after I/R. But at 7th day, infarct volume in left MCAO group was significantly larger than that in the right MCAO group.Conclusion Whether the left or the right MCAO model does not much affect the infarct volume at early stage. However, the infarct volume of left MCAO was larger than that of right MCAO at later stage. More serious movement is caused in the left MCAO group and more serious memory impairments is caused in the right MCAO group. These findings suggest there may be structural and functional asymmetry in hemispheres of rat, which affects the outcome of the focal cerebral ischemia.