淫羊藿黄酮对APP转基因小鼠学习记忆及β-amyloid生成的影响

Effects of epimedium flavonoids on learning-memory ability and development of β-amyloid of APP transgenic mice

观察不同月龄APP(amyloid precursor protein)转基因模型小鼠学习记忆功能的改变,以及中药有效部位淫羊藿黄酮对10月龄转基因小鼠学习记忆功能和脑内APP、BACE的表达及β-淀粉样肽(β-amyloid,Aβ)生成及含量的影响.用药组小鼠自4月龄开始灌胃给予淫羊藿黄酮小(0.03hg·kg-1/d)、大剂量(0.1g·kg-1/d)6个月至10月龄,正常对照组、转基因阴性对照组及模型组以同样方式灌胃给予蒸馏水.应用Morris水迷宫和物体识别方法测试小鼠学习记忆能力,应用免疫组化学及WesternBlot方法分别检测海马CA1区及皮层中APP、BACE的表达,采用双抗体夹心ELISA试剂盒测定海马中不溶性Aβ1-42含量.研究结果表明,APP转基因小鼠在4月龄即出现学习记忆能力障碍,在水迷宫实验中,比转基因阴性对照组小鼠潜伏期延长28%(p<0.05).增龄至10月龄,APP转基因小鼠学习记忆能力明显下降,水迷宫潜伏期及游泳距离与转基因阴性对照组的差异分别加大为40%(p<0.01)和35%(p<0.05),物体识别实验中分辨指数的差异为61%(p<0.05).与正常对照组及转基因阴性对照组相比,10月龄转基因模型小鼠海马CA1区及皮层中APP和BACE的表达明显增加,海马中Aβ1-42的含量明显升高.淫羊藿黄酮大剂量可明显改善10月龄APP转基因小鼠Morris水迷宫作业成绩,提高模型鼠物体识别能力,明显减少APP转基因模型小鼠海马和皮层APP及BACE的表达,降低海马Aβ1-42的含量.提示淫羊藿黄酮能改善APP转基因模型小鼠学习记忆能力和减少Aβ经由淀粉源途径生成及含量,对防治AD等神经退行性疾病具有良好的应用前景.

Learning-memory deficit in different ages of APP （amyloid precursor protein） transgenic mice was investigated and the protective effects of epimedium flavonoids （EF） were observed on development of β-amyloid in brain of 10 months old of APP transgenic mice. The mice of drug treated group were administered introgastrically by EF （at doses 0.03 and 0. 1 g · kg^-1/d） from 4 to 10 months old. The mice of normal group and negative transgene group were administered of distilled water by the same way. The learning-memory ability was measured by applying Morris water maze （MWM） and object recognition test （ORT）. The expression of APP and β-secretase （BACE） in hippocampus and cortex were detected by immunohistochemistry and Western Blot respectively. The content of insoluble β-amyloid1-42 （Aβ1-42） in hippocampus were measured by ELISA Assay Kit. The results show that learning-memory deficit was detected in 4 months old Tg mice. The learning-memory deficit was aggravated in 10 months old Tg mice. Their escape latency and swimming distance in MWM was prolonged, and the discrimination index decreased in ORT. Epimedium flavonoids improved learning-memory impairment of 10 months old Tg mice in MWM as well as in ORT, and decreased the expression of APP, BACE and the content of Aβ1-42 in brains. These results suggest that different ages of Tg mice could mimic pathological proceeding of AD. Epimedium flavonoids may have a promising application prospect in treatment of AD.