Abstract：
Alzheimer\'s disease (AD) is a neurodegenerative disease and the most frequent cause of dementia. It is characterized by the accumulation in the brain of two pathological protein aggregates: amyloid-β peptides (Aβ) and abnormally phosphorylated tau. The progressive cognitive decline observed in patients strongly correlates with the synaptic loss. Many lines of evidence suggest that soluble forms of Aβ accumulate into the brain where they cause synapse degeneration. Stopping their spreading and/or targeting the pathophysiological mechanisms leading to synaptic loss would logically be beneficial for the patients. However, we are still far from understanding these processes. Our objective was therefore to develop a versatile model to assay and study Aβ-induced synaptotoxicity. We integrated a microfluidic device that physically isolates synapses from presynaptic and postsynaptic neurons with a microelectrode array. We seeded mouse primary cortical cells in the presynaptic and postsynaptic chambers. After functional synapses have formed in the synaptic chamber, we exposed them to concentrated conditioned media from cell lines overexpressing the wild-type or mutated amyloid precursor protein and thus secreting different levels of Aβ. We recorded the neuronal activity before and after exposition to Aβ and quantified Aβ\'s effects on the connectivity between presynaptic and postsynaptic neurons. We observed that the application of Aβ on the synapses for 48 h strongly decreased the interchamber connectivity without significantly affecting the neuronal activity in the presynaptic or postsynaptic chambers. Thus, through this model, we are able to functionally assay the impact of Aβ peptides (or other molecules) on synaptic connectivity and to use the latter as a proxy to study Aβ-induced synaptotoxicity. Moreover, since the presynaptic, postsynaptic, and synaptic chambers can be individually targeted, our assay provides a powerful tool to evaluate the involvement of candidate genes in synaptic vulnerability and/or test therapeutic strategies for AD.
摘要：
阿尔茨海默病(Alzheimer’sdisease,AD)是一种神经退行性疾病,是痴呆的最常见原因。其特征在于两种病理蛋白聚集体在脑中的积累:淀粉样蛋白-β肽(Aβ)和异常磷酸化的tau。在患者中观察到的进行性认知下降与突触丢失密切相关。许多证据表明，Aβ的可溶性形式会积聚到大脑中，从而导致突触变性。停止它们的扩散和/或靶向导致突触丧失的病理生理机制在逻辑上对患者是有益的。然而,我们还远远没有理解这些过程。因此，我们的目标是开发一种通用模型来测定和研究Aβ诱导的突触毒性。我们集成了微流体装置，该装置将突触与突触前和突触后神经元物理隔离，并使用微电极阵列。我们在突触前室和突触后室中接种了小鼠原代皮层细胞。在突触腔中形成功能性突触后，我们将它们暴露于来自过表达野生型或突变淀粉样蛋白前体蛋白的细胞系的浓缩条件培养基中，从而分泌不同水平的Aβ。我们记录了暴露于Aβ之前和之后的神经元活动，并量化了Aβ对突触前和突触后神经元之间连通性的影响。我们观察到，在突触上应用Aβ48小时会大大降低腔室之间的连通性，而不会显着影响突触前或突触后腔室中的神经元活动。因此，通过这个模型，我们能够功能分析Aβ肽（或其他分子）对突触连接的影响，并使用后者作为研究Aβ诱导的突触毒性的替代方法。此外，自从突触前，突触后，突触室可以单独靶向，我们的检测方法为评估候选基因参与突触易损性和/或测试AD治疗策略提供了一个强大的工具.
