阿尔茨海默病转基因果蝇模型β淀粉样蛋白对胆碱能突触的毒性影响

Toxic effects of amyloid-β peptides on cholinergic synapses in transgenic Drosophila models of Alzheimer’s disease

摘要:

目的 研究β淀粉样蛋白（Aβ）多肽对阿尔茨海默病（AD）转基因果蝇大脑中胆碱神能经元突触的影响。方法 分别建立转Aβ40，Aβ42基因果蝇AD两个模型组，以野生果蝇（canton-s）作为对照组。采用生物素染色和激光共聚焦成像记录投射神经元的形态；通过全细胞膜片钳方法记录各组投射神经元胆碱能的自发突触后电流和微兴奋性突触后电流；检测各组果蝇的嗅觉短期记忆能力。结果 与对照组相比较，Aβ42组的自发突触后电流的频率和振幅均有明显降低，差异有统计学意义（P<0.05）；Aβ42组微兴奋性突触后电流的频率明显下降，差异有统计学意义（P<0.05）。在巴甫洛夫的嗅觉相关的短期学习记忆测试中，与对照组相比较，Aβ40，Aβ42两组果蝇学习记忆指数均明显降低，差异有统计学意义（P均<0.05）。结论 Aβ肽对胆碱能突触传递的影响提示，其可能是由Aβ肽引起胆碱能神经元变性和记忆不断下降的可能机制之一。

Abstract:

Objective To study the effects of amyloid-β (Aβ) peptides on the cholinergic synapses in the brain of transgenic Drosophila with Alzheimer's disease (AD).Methods An Aβ40-expressing transgenic Drosophila model of AD (Aβ40 group) and an Aβ42-expressing transgenic Drosophila model of AD (Aβ42 group) were established, and wild-type Drosophila (Canton-S) was used as control group. Avidin-biotin staining and confocal laser scanning microscopy were used to record the morphology of projection neurons. The cholinergic spontaneous postsynaptic currents (sPSCs) and miniature excitatory postsynaptic currents (mEPSCs) of projection neurons were recorded by whole-cell patch clamp technique. The short-term olfactory memory was tested by Pavlovian olfactory learning assay.Results Compared with the control group, the Aβ42 group had significantly decreased frequency and amplitude of sPSCs (P<0.05) and significantly decreased frequency of mEPSCs (P<0.05). The Pavlovian olfactory learning assay showed that the Aβ40 and Aβ42 groups had significantly decreased learning and memory indices compared with the control group (P<0.05 for both).Conclusions The effects of Aβ peptides on cholinergic synaptic transmission suggest a possible mechanism by which Aβ peptides cause cholinergic neuron degeneration and the consequent memory loss.