Alpha-synuclein driven cellular changes and vocal dysfunction in Parkinson's Disease

摘要 帕金森氏病(PD)的诊断延迟，延误了治疗，限制了阻止疾病的能力 进步。以帕金森病前驱期为靶点的治疗，在主要运动出现之前 症状(震颤、僵硬等)和产生多巴胺的神经元的退化不存在，因为我们缺乏 可靠的早期疾病生物标志物。根据越来越多的证据，发声功能障碍在 帕金森病的前驱期，为识别早期神经病变提供了一个方便的切入点 潜在的治疗目标。来自我们实验室和其他实验室的数据表明，已知的 啮齿动物和雀类脑中人类帕金森病致病基因α-突触核蛋白(α-syn，snca)导致早期发声 与人类疾病相一致的异常。作为一种突触蛋白，α-syn在细胞功能中起着至关重要的作用 包括促进神经递质的释放。它对帕金森病的细胞毒性已被人体临床试验靶向 但在疾病后期，神经病理已经很普遍了。事实上，人们对此知之甚少 在帕金森病早期，α-SYN的生理作用转变为病理生理作用。这份R21提案解决了以下问题 通过研究多年前可能发生的发声运动输出的早期异常来研究不足之处 传统的运动症状。我们建议开发一个综合的、早期阶段的平台，用于评估 α-SYN介导的神经元和突触活动的变化，导致异常的发声输出。要做到这一点，我们使用 斑马雀模型系统，因为它有专门的歌唱专用脑核，可以在实验中使用 有针对性的；特定于细胞的活动变化随后与声音输出直接相关。Area X是一首专属歌曲 雀类基底节内的核。在X区，纹状体中棘神经元(MSN)和球体 苍白球样(PAL)投射神经元表现出与歌唱有关的放电活动，这与脑电活动的变化直接相关 歌曲结构。当α-SYN在X区病毒过度表达时，我们检测到歌曲中类似PD的变化，包括 降低了音调、幅度和异常时序。在目标1中，我们测试了这些歌曲改变结果的假设 从细胞外植入自由行为鸟类的MSN活性降低和PAL活性增加 电极阵列。目的2验证α-SYN在X区过度表达导致时间依赖的 MSN谷氨酸能电流的抑制和PAL神经元GABA能电流的增强 切片。我们强大的综合方法使用体内和体外神经活动的测量来评估 α-SYN驱动的特定神经元亚型的变化如何与行为输出相关。这个 早期帕金森病样发声障碍的神经病理生理机制的表征将提供 新的疾病修正治疗目标。

SUMMARY Diagnosis of Parkinson’s Disease (PD) is made late, delaying treatment and limiting the ability to halt disease progression. Treatments that target the prodromal phase of PD, prior to the appearance of the cardinal motor signs (tremor, rigidity, etc) and the degeneration of dopamine-producing neurons, do not exist because we lack reliable biomarkers of early disease. Based on accumulating evidence, vocal dysfunction is present during the prodromal phase of PD and offers a convenient entry point to identify early neuropathological changes as potential treatment targets. Data from our laboratory and others has shown that the overexpression of a known human-PD causing gene, alpha-synuclein (α-syn, SNCA) in the rodent and finch brain, leads to early vocal abnormalities consistent with human disease. As a synaptic protein, α-syn is critically involved in cell functions including facilitating neurotransmitter release. Its cellular toxicity in PD has been targeted in human clinical trials but late in the disease, when the neuropathology is already widespread. In fact, little is known about how the physiological role of α-syn shifts to a pathophysiological one early on in PD. This R21 proposal addresses these shortcomings by investigating early stage abnormalities in vocal motor output that can occur years before traditional motor symptoms. We propose to develop an integrated, early stage platform for the evaluation of the α-syn-mediated changes in neuronal and synaptic activity that drive abnormal vocal output. To do so, we use the zebra finch model system because it has specialized song-dedicated brain nuclei that can be experimentally targeted; cell-specific changes in activity are then directly related to the vocal output. Area X is a song-dedicated nucleus within the finch basal ganglia. Within Area X, striatal Medium Spiny Neurons (MSNs) and Globus Pallidus-like (PAL) projection neurons show singing-related firing activity that is directly related to variations in song structure. When α-syn is virally overexpressed in Area X, we detect PD-like changes in song including reduced pitch, amplitude, and abnormal timing. In Aim 1, we test the hypothesis that these song changes result from reduced MSN activity and increased PAL activity in freely behaving birds implanted with extracellular electrode arrays. Aim 2 tests the hypothesis that α-syn overexpression in Area X results in a time-dependent suppression of glutamatergic currents in MSNs and enhanced GABAergic currents in PAL neurons in living brain slices. Our powerful integrative approach uses in vivo and ex vivo measurements of neural activity to evaluate how α-syn driven changes in specific neuronal sub-types correlates to the behavioral output. The characterization of neuropathophysiological mechanisms underlying early stage PD-like vocal deficits will offer new disease-modifying treatment targets.