17β-雌二醇降低大鼠慢性低灌注诱导的空间记忆损伤及其分子机制

17β-estradiol retards memory impairment induced by chronic hypoperfusion in rats and its molecular mechanism

目的 :观察慢性低灌注3个月大鼠空间学习、记忆能力的变化及17β-雌二醇(E2)的长期保护作用,揭示血管性痴呆进行性病变的分子机制。方法:永久性结扎成年雄性SD大鼠双侧颈总动脉,诱导慢性低灌注模型,并随机分为假手术(sham)组、安慰剂(placebo,Pla)组及E2处理组;采用免疫荧光染色或Western blot技术检测海马CA1区神经元及突触相关蛋白的变化,采用Morris水迷宫检测大鼠空间记忆能力。结果:1Morris水迷宫结果显示,Pla组大鼠发现水下平台所用时间与sham组大鼠相比无显著差异,而探索试验中在平台原所在象限探索的时间较sham组大鼠显著降低;2与sham组相比,Pla组大鼠海马CA1区Neu N阳性染色细胞数及微管相关蛋白(microtubule-associated protein,MAP)-2的蛋白表达水平无显著差异,而髓鞘碱性蛋白(myelin basic protein,MBP)-2的蛋白表达水平显著降低;3Pla组大鼠海马CA1区突出后致密蛋白95(post-synaptic density protein 95,PSD95)及突触小泡蛋白的蛋白表达水平较sham组显著降低;4长期给予E2可显著治疗双侧颈总动脉结扎造成的以上变化。结论:双侧颈总动脉结扎3个月可导致大鼠空间记忆能力降低,长期给予E2可能通过上调海马CA1区神经元MBP2、PSD95、突触小泡蛋白的蛋白表达,从而阻断血管性痴呆的进行性病变。

Objective：To investigate change in spatial learning and memory function of rats following chronic hypoperfusion for 3 months,and the neuroprotective effect of long-term treatment with 17β-estrogen （E2）,which aims to outline the molecular mechanisms of progressive lesions in vascular dementia. Methods：Chronic hypoperfusion in adult male Sprague–Dawley rats was induced by permanent bilateral common carotid artery occlusion （BCCAO） and the rats were randomly assigned into three groups：the sham group,the placebo （Pla） and the E2 group. Morris water maze was performed to observe spatial learning and memory function of rats. Immunofluorescence staining and Western blot analysis were performed to detect protein expressions of synaptic markers in hippocampal CA1 region. Results：（1） Morris water maze analysis revealed no statistical differencal in latency time to find sub-water platform between the sham and the Pla groups,but the Pla group significantly decreased probe time in the quadrant where the platform was previously located compared to sham animals. （2） Compared with the sham group,the number of NeuN-positive cells and the protein level of microtubule-associated protein （MAP） 2 of the Pla group had no significant changes,however,the levels of myelin basic protein （MBP）-2 were significantly decreased. （3） In the Pla group,post-synaptic density protein 95 （PSD95） and synaptophysin were significantly decreased compared to the sham group in hippocampal CA1 region. （4） Long-term treatment with E2 reversed these changes induced by BCCAO. Conclusion：BCCAO for 3 mon could lead to decreased spatial learning and memory function of rats. Long-term treatment of E2 may block progressive lesions in vascular dementia by up-regulating MBP2,PSD95 and synaptophysin in hippocampal CA1 region.