Targeting the NMDA receptor-mediated disruption of autonomous subthalamic nucleus activity to ameliorate physiological and motor symptoms in a mouse model of Parkinson's Disease

描述(申请人提供)：黑质多巴胺神经元的退化通过深刻改变皮质-基底节-丘脑-皮质环路的活动频率和模式，驱动特发性和实验性帕金森病(PD)的核心运动症状。经典的基底节功能障碍模型认为，多巴胺的丢失导致间接(运动抑制)途径相对于直接(促进运动)途径的活性增加。然而，L-多巴酚丁胺和丘脑底核深部脑刺激等治疗干预措施并不改变放电频率，其方式与速率模型一致。相反，实验性和特发性帕金森病患者运动症状的改善与异常的、持续的、同步的频段(13-30赫兹)活动的减少更密切相关。然而，帕金森病异常条带活动的原因仍不清楚。我们发现，在帕金森病的单侧6-羟基多巴胺(6-OHDA)损毁模型中，作为间接和超直接通路的组成部分，STN的自主活动丢失。活性的丧失似乎是通过NMDA受体(R)介导的ATP依赖的钾(KATP)通道电导的上调，从而使STN神经元超极化。去相关的自主STN活动的丧失可能增加了STN的皮质模式，从而有助于PD及其模型中条带活动的放大和持续。因此，这项拟议的项目将调查STN自主活动中断的潜在机制，并确定拯救固有的STN兴奋性是否对实验性PD具有治疗作用。利用病毒载体介导的遗传操作、体内外电生理记录和6-OHDA小鼠帕金森病模型的运动行为测试的组合，将解决三个特定的目标。申请人将确定：1)体内STN NMDA受体的敲除是否可以防止自主STN活性的丧失，以及上调STN KATP通道的NMDAR相关信号通路的缺失；2)STN NMDAR受体的敲除是否使皮质-基底节-丘脑-皮质环活动正常化，改善运动功能障碍；以及3)通过表达和激活设计药物(DREADDS)独有激活的设计受体(DREADDS)来恢复固有的STN活性是否使皮质-基底节-丘脑-皮质环活动正常化，并改善运动功能障碍。通过拟议的培训计划，申请者将获得分子、电生理学、解剖学和行为技术方面的专业知识，并发展必要的分析和沟通技能，以实现她成为一名专注于疾病机制和治疗的独立神经科学家的目标。

DESCRIPTION (provided by applicant): The degeneration of substantia nigra dopamine neurons drives the core motor symptoms of idiopathic and experimental Parkinson's disease (PD) by profoundly altering the frequency and pattern of activity in the cortico-basal ganglia-thalamo-cortical loop. The classical rate model of basal ganglia dysfunction suggests that loss of dopamine results in an increase in the activity of the indirect (movement-inhibiting) pathway relative to the activity of the direct (movement-promoting) pathway. However, therapeutic interventions such as L-DOPA and deep brain stimulation (DBS) of the subthalamic nucleus (STN) do not alter firing rates in a manner that is consistent with the rate model. Instead, the amelioration of motor symptoms in experimental and idiopathic PD is more closely related to reductions in abnormal, persistent, synchronous, band (13-30Hz) activity. However, the causes of abnormal-band activity in PD remain poorly defined. We have found that the autonomous activity of the STN, which is a component of the indirect and hyperdirect pathways, is lost in the unilateral 6-hydroxydopamine (6- OHDA) lesion model of PD. Loss of activity appears to be through NMDA receptor (R)-mediated upregulation of an ATP-dependent potassium (KATP) channel conductance that hyperpolarizes STN neurons. Loss of decorrelating autonomous STN activity may increase cortical patterning of the STN and thus contribute to the amplification and persistence of band activity in PD and its models. The proposed project will therefore investigate the mechanisms underlying the disruption of autonomous STN activity and determine whether the rescue of intrinsic STN excitability is therapeutic in experimental PD. Using a combination of viral vector-mediated genetic manipulations, electrophysiological recording ex vivo and in vivo and motor behavioral testing in the 6-OHDA mouse model of PD, 3 Specific Aims will be addressed. The applicant will determine: 1) whether knockdown of STN NMDA receptors in vivo prevents loss of autonomous STN activity, and the NMDAR-linked signaling pathways that upregulate STN KATP channels; 2) whether knockdown of STN NMDARs normalizes cortico-basal ganglia-thalamo- cortical loop activity and ameliorates motor dysfunction; and 3) whether restoration of intrinsic STN activity through expression and activation of designer receptors exclusively activated by designer drugs (DREADDs) normalizes cortico-basal ganglia-thalamo-cortical loop activity and ameliorates motor dysfunction. Through the proposed training plan the applicant will gain expertise in molecular, electrophysiological, anatomical and behavioral techniques and develop the analytical and communication skills necessary to achieve her goal of becoming an independent neuroscientist focused on disease mechanisms and therapeutics.