NOVEL EXPERIMENTAL PLATFORM FOR PRODOMAL PARKINSON'S DISEASE

 描述（由申请人提供）：帕金森病（PD）是一种运动障碍，其标志性运动症状是由于纹状体多巴胺能神经支配的丧失而引起的。运动症状包括运动减慢、协调性下降和步态异常。这些症状通常不会出现，直到纹状体中的多巴胺水平降低了70- 80%。在临床上，这意味着在运动症状发作时寻求医疗帮助的患者可能多年来一直生活在长期低水平的多巴胺中。这种疾病的早期阶段，当多巴胺水平处于病理性低水平但尚未出现运动症状时，被称为前驱期，并且可能是实施治疗的最佳时期。然而，大多数利用帕金森病运动障碍动物模型的研究仅在严重运动功能障碍已经发生后的耗尽晚期阶段调查回路功能障碍。这些动物模型极大地推进了我们对大量多巴胺耗尽动物中存在的突触和回路水平变化的理解，但我们仍然对回路功能障碍的进展或导致运动障碍出现的代偿性可塑性知之甚少，这一理解对于在疾病变得不可治愈之前阻止疾病进展至关重要。拟议研究的主要目标是研究回路功能障碍和补偿的进展，导致运动缺陷的出现，使用一种新的多巴胺耗竭范式，其中多巴胺损失的发作和进展可以严格控制。 在目标1中，我们将进行一个无偏见的，高通量的屏幕显示差异激活的小鼠在几周到几个月逐渐耗尽，相对于急性耗尽小鼠的脑区。在急性和逐渐耗尽的动物中显示差异活动的脑区将确定补偿可塑性的潜在位点，为未来研究前驱PD期间网络适应的细胞和突触机制提供基础。在目标2中，我们将通过比较逐渐耗尽小鼠的大脑活动模式与在已建立的PD遗传模型Thy 1-αSyn中观察到的模式来验证我们的模型，其中到14个月大时约40%的多巴胺丢失。在两种模型中表现出共同变化的大脑区域将揭示疾病相关可塑性的最有希望的部位。最后，在目标3中，我们将使用最先进的电生理方法来记录在我们的逐渐耗尽范式的持续时间内候选大脑区域的神经活动。这些实验将确定导致运动缺陷出现的网络补偿的神经相关性。结合，这些结果将提供新的见解的位置和进展的代偿可塑性在前驱PD，并将奠定基础，为未来的研究疾病的细胞和突触基础的适应性可塑性。

 DESCRIPTION (provided by applicant): Parkinson's disease (PD) is a movement disorder whose hallmark motor symptoms arise due to loss of dopaminergic innervation of the striatum. Motor symptoms include slowed movement, decreased coordination, and gait abnormalities. These symptoms typically do not present until dopamine levels in the striatum have been reduced by 70-80%. Clinically, this means that patients who seek medical help at the onset of motor symptoms have likely been living with chronically low levels of dopamine for years. This early phase of the disease, when dopamine levels are pathologically low but motor symptoms have not yet presented, is called the prodromal phase, and is likely the optimal period in which to administer therapies. However, most research utilizing animal models of parkinsonian motor impairments investigates circuit dysfunction only in late stages of depletion, after severe motor dysfunction has already occurred. These animal models have greatly advanced our understanding of the synaptic and circuit-level changes present in massively dopamine depleted animals, but we still know very little about the progression of circuit dysfunction, or compensatory plasticity leading up to the appearance of motor impairments, an understanding that may be critical to halting disease progression before it becomes incurable. The primary goal of the proposed research is to study the progression of circuit dysfunction and compensation leading up to the appearance of motor deficits using a novel dopamine depletion paradigm where the onset and progression of dopamine loss can be tightly controlled. In Aim 1, we will conduct a nonbiased, high throughput screen for brain areas showing differential activation in mice gradually depleted over weeks to months, relative to acutely depleted mice. Brain areas showing differential activity in acutely vs. gradually depleted animals will identify potential sits of compensatory plasticity, providing a foundation for future studies of the cellular and synaptic mechanisms of network adaptations during prodromal PD. In Aim 2, we will validate our model by comparing patterns of brain activity in gradually depleted mice to those observed in an established genetic model of PD, Thy1-αSyn, where ~40% of dopamine is lost by age 14 months. Brain areas showing common changes across both models will reveal the most promising sites of disease-relevant plasticity. Finally, in Aim 3, we will use cutting-edge electrophysiological approaches to record neural activity in candidate brain areas over the duration of our gradual depletion paradigm. These experiments will identify neural correlates of network compensation leading up the appearance of motor deficits. Combined, these results will provide novel insights into the location and progression of compensatory plasticity during prodromal PD, and will lay the foundation for future studies of the cellular and synaptic basis of adaptive plasticity in disease.