颈动脉狭窄对大鼠认知功能及海马神经元凋亡的影响

Effects of carotid artery stenosis on the cognitive function and hippocampal neuronal apoptosis in rats

目的探讨颈动脉狭窄大鼠认知功能改变与海马神经元凋亡及BCL-2、BAX蛋白表达的关系。方法雄性SD大鼠36只,随机分为假手术组、狭窄2、4、8周组,每组9只大鼠。制备颈动脉狭窄模型后,各组采用Morris水迷宫检测记忆能力,TUNEL法观察海马神经元凋亡,免疫组化检测BCL-2、BAX蛋白表达。结果①狭窄组各时相点与假手术组比较,平均逃避潜伏期延长,平台象限游泳距离百分比降低,差异有统计学意义,P<0.01。随狭窄时间的延长,平均逃避潜伏期逐渐增加,平台象限游泳距离百分比逐渐降低。②各狭窄组大鼠的凋亡神经元比例高于假手术组,随狭窄时间的延长,凋亡神经元的比例逐渐升高,差异均有统计学意义。③BCL-2蛋白在狭窄2周组达高峰,狭窄4周和狭窄8周组逐渐减弱,均高于假手术组,差异有统计学意义。④BAX蛋白表达在2周时表达增强,8周时达高峰,均高于假手术组,差异有统计学意义。结论颈动脉狭窄大鼠海马神经细胞BCL-2/BAX蛋白比例失衡引起海马神经细胞凋亡,可能是大鼠颈动脉狭窄后出现认知功能障碍的机制之一。

Objective To investigate the relationship between carotid artery stenosis caused cognitive functional impairment and hippocampal neuronal apoptosis and expression of BCL-2/BAX protein in rats. Methods A total of 36 male SD rats were randomly allocated into sham operation, stenosis 2-, 4-, and 8- week groups. After the rat model of carotid stenosis was developed, the Morris water maze was used to detect the memory ability of rats in each group, TUNEL assay was used to observe hippocampal neuronal apoptosis, and immunohistochemistry was used to detect the expression of BCL-2/BAX protein. Results （1）Compared to the sham operation group, the mean escape latency of rats was extended at each time point in the stenosis groups. The percentage of swimming distance in the platform quadrant was decreased. There was statistical significance（P 〈0. 01）. With the stenotic time prolonged, the mean escape latency increased gradually, meanwhile the percentage of platform quadrant swimming distance decreased gradually. （2）The proportion of neuronal apoptosis in every stenosis group was higher than that in the sham operation group. There were statistical significances with the stenotic time prolonged and the gradual increase of neuronal apoptosis. （3）The level of BCL-2 protein reached the peak in the stenosis 2-week group, and it was decreased gradually in the stenosis 4- and 8-week groups, both of them were significantly higher than that in the sham operation group. （4）BAX protein expression enhanced at 2 weeks, and it reached the peak at 8 weeks. They were all significantly higher than that in the sham operation group. Conclusion The proportional imbalance of hippocampus expression of BCL-2/BAX protein caused hippocampal neuronal apoptosis may be one of the mechanisms of cognitive impairment after carotid artery stenosis in rats.