颞叶癫痫幼鼠海马神经发生与Miat及Wnt7b/β-catenin信号通路的变化

Changes of Miat and Wnt7b/β-Catenin Signaling Pathway in Hippocampal Neurogenesis of Immature Rats with Temporal Lobe Epilepsy

目的:探讨颞叶癫痫幼鼠海马神经发生与Miat及Wnt7b/β-catenin信号通路的变化。方法:将日龄21~23 d的幼鼠分为生理盐水(NS)组与红藻氨酸(KA)组,每组18只。取KA组幼鼠侧脑室注射KA构建颞叶癫痫模型,埋入脑电波接收电极,观察幼鼠的癫痫发作情况与脑电波变化情况。在第1周、第4周、第8周通过Y型迷宫检测幼鼠学习、记忆能力。取幼鼠脑组织,包埋切片后检测BrdU阳性细胞数与DCX蛋白表达。镊取幼鼠海马组织,提取RNA检测Miat含量,提取蛋白检测Wnt7b/β-catenin信号蛋白表达。结果:KA组幼鼠在不同时期出现癫痫发作,脑电波连续出现高频/高幅棘波;随着时间进展,与KA-1周组发作频率[(7.50±1.87)次/天]、发作等级(3.31±0.48)相比,KA-8周组癫痫发作频率[(2.33±1.21)次/天]与等级(1.19±0.40)降低(P<0.05),脑电波中高频/高幅棘波间歇性出现。Y型迷宫中,与NS组相比,KA组幼鼠正确反应次数减少,正确反应时间延长;与KA-1周组正确反应次数[(8.17±1.72)次]、正确反应时间[(11.83±1.72)s]相比,KA-8周组幼鼠正确反应次数[(10.50±2.74)次]增加,正确反应时间[(9.50±2.74)s]缩短。与NS组相比,KA组幼鼠BrdU阳性细胞数、DCX蛋白表达、Miat含量、Wnt7b/β-catenin信号通路与BDNF/TrkB信号通路蛋白表达减少(P<0.05);与KA-1周组相比,KA-8周组幼鼠BrdU阳性细胞数、DCX蛋白表达、Miat含量、Wnt7b/β-catenin信号通路与BDNF/TrkB信号通路蛋白表达增加(P<0.05)。结论:颞叶癫痫幼鼠海马体中存在神经发生减少,这可能与抑制Miat及Wnt7b/β-catenin信号通路相关。

Objective: To investigate the changes of Miat and Wnt7b/β-catenin signaling pathway in hippocampal neurogenesis of immature rats with temporal lobe epilepsy.Methods:Immature rats aged from 21 to 23 d were divided into the normal saline(NS)group and the kainic acid(KA)group,with 18 rats in each group.The temporal lobe epilepsy model was established by intracerebroventricular injection of KA in the KA group,and the electrode of electroencephalography was embedded.The epilepsy and electroencephalography changes of the immature rats were observed.At the 1^(st),4^(th),and 8^(th) weeks,the learning and memory abilities of the immature rats were tested by Y-maze.The brain tissues of immature rats were collected,and the number of BrdU positive cells and expression of DCX protein were detected after embedding sections.Hippocampal tissues of immature rats were collected,RNA was extracted to detect the content of Miat,and protein was extracted to detect the expression of Wnt7b/β-catenin signaling protein.Results:The immature rats in KA group had epileptic seizures at different periods,and the electroencephalography showed continuous high-frequency/high-amplitude spikes.As time goes on,compared with the epilepsy frequency(7.50±1.87)times/day and epilepsy grade(3.31±0.48)in the KA-1 w group,the epilepsy frequency(2.33±1.21)times/day and epilepsy grade(1.19±0.40)in the KA-8 w group decreased(P<0.05),and high-frequency/high-amplitude spikes appeared intermittently in brain waves.In the Y-maze,compared with the NS group,the number of correct response of KA group decreased,and the correct response duration prolonged.Compared with the number of correct response(8.17±1.72)times and correct response duration(11.83±1.72)s in the KA-1 w group,the number of correct response(10.50±2.74)times in the KA-8 w group increased,the correct response duration(9.50±2.74)s shortened.Compared with the NS group,the number of BrdU positive cells,DCX protein expression,Miat content,Wnt7b/β-catenin signaling pathway and BDNF/TrkB signaling pathway protein expression in the KA group decreased(P<0.05).Compared with the KA-1 w group,the number of BrdU positive cells,DCX protein expression,Miat content,Wnt7b/β-catenin signaling pathway and BDNF/TrkB signaling pathway protein expression in the KA-8 w group increased(P<0.05).Conclusion:There is a decrease in neurogenesis in the hippocampus of immature rats with temporal lobe epilepsy,which may be related to the inhibition of Miat and Wnt7b/β-catenin signaling pathway.