重复经颅磁刺激对血管性痴呆大鼠学习记忆功能及海马胆碱能系统的影响

目的:观察重复经颅磁刺激(rTMS)对血管性痴呆(VaD)大鼠学习记忆功能及海马胆碱能系统的影响,并探讨其可能的作用机制。方法:雄性SD大鼠54只,随机分为对照组、模型组、rTMS组,每组18只。采用两血管阻断法制作VaD模型,对照组仅分离暴露双侧颈总动脉而不结扎。rTMS组于制模成功后给予rTMS治疗,模型组模拟rTMS固定大鼠头部放置线圈但不给予脉冲磁刺激。各组在造模第30天应用Morris水迷宫试验检测学习记忆能力,测定海马内乙酰胆碱酯酶(AChE)及胆碱乙酰转移酶(ChAT)的活性,行海马CA1区胆碱酯酶阳性纤维染色及密度测定,应用免疫组化技术检测海马CA1区脑源性神经营养因子(BDNF)的表达。结果:与模型组相比,rTMS组水迷宫逃避潜伏期明显缩短(P<0.05),相同时间内在原平台象限跨越相应平台次数明显增多(P<0.05);与对照组相比,模型组及rTMS组AChE及ChAT的活性均明显降低(P<0.05);与模型组相比,rTMS组AChE及ChAT的活性均明显增加(P<0.05);rTMS组海马CA1区乙酰胆碱酯酶阳性纤维的密度及BDNF的表达均较模型组明显增强(P<0.05)。结论:rTMS能改善VaD大鼠学习记忆功能,机制可能与rTMS治疗能促进海马CA1区BDNF的表达、恢复海马胆碱能系统活性有关。

Effects of Repetitive Transcranial Magnetic Stimulation on the Abilities of Learning and Memory and the Cholinergic System of Hippocampus Formation in Rats with Vascular Dementia

ObjectiveTo investigate the effects of repetitive transcranial magnetic stimulation （rTMS） on the abilities of learning and memory and the cholinergic system of hippocampus formation in rats with vascular dementia （VaD） . Methods： Fifty-four male SD rats were randomly divided into control, VaD model and rTMS groups with 18 rats in each group. The VaD rats were established with two vessel occlusion method whereas bilat-eral carotid arteries were only exposed without ligation in the control group. The animals in the rTMS group were given rTMS treatment. The rats in the model group were treated by simulated rTMS and fixed head coil without impulse magnetic stimulation. Morris water maze （MWM） test was performed to evaluate learning and memory function of rats on the day 30 after two vessel occlusion. The activity of AchE and ChAT, the density of AChE-positive staining fiber and the expression of brain-derived neurotrophic factor （BDNF） in hippocampus were investigated. Results：The MWM escape latency in the rTMS group was shorter than that in the model group P〈0.05）. The number of crossing the corresponding platform during the same time period in platform quad-rant in the rTMS group was significant more than that in the model group（ P〈0.05）. The activity of AchE and ChAT was decreased significantly in the model group compared with those in the control group, whereas it was improved significantly in the rTMS group（ P〈0.05）. The density of AChE-positive staining fiber and the expres-sion of BDNF in the rTMS group were higher than those in the model group（ P〈0.05）. Conclusion：rTMS can ameliorate learning and memory deficit of rats with VaD, perhaps by way of increased expression of BDNF in hippocampus CA1 area and repair of hippocampal cholinergic system activity.