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（由申请人提供）：黑质多巴胺神经元的退化通过深刻改变皮质-基底神经节-丘脑-皮层回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。基底神经节功能障碍的经典速率模型表明，多巴胺的缺失导致间接（运动抑制）通路的活性相对于直接（运动促进）通路的活性增加。然而，治疗性干预，如左旋多巴和丘脑下核深部脑刺激（DBS），并没有以与速率模型一致的方式改变放电速率。相反，实验性和特发性PD患者运动症状的改善与异常、持续、同步、频带（13-30Hz）活动的减少更密切相关。然而，PD中异常带活动的原因仍然不明确。我们发现，在PD的单侧6-羟多巴胺（6- OHDA）损伤模型中，作为间接和超直接通路组成部分的STN的自主活性丧失。活性丧失似乎是通过NMDA受体(R)介导的atp依赖性钾（KATP）通道电导的上调，导致STN神经元超极化。去相关自主STN活动的丧失可能会增加STN的皮质模式，从而有助于PD及其模型中带状活动的扩增和持续。因此，拟议的项目将研究自主STN活动中断的机制，并确定在实验性PD中，拯救STN的固有兴奋性是否具有治疗作用。结合病毒载体介导的遗传操作，体外和体内电生理记录以及6-OHDA PD小鼠模型的运动行为测试，将解决3个具体目标。申请人将确定：1)体内STN NMDA受体的敲低是否可以防止STN自主活性的丧失，以及上调STN KATP通道的NMDA相关信号通路；2) STN NMDARs的下调是否能使皮质-基底节区-丘脑-皮质环的活动正常化并改善运动功能障碍；3)是否通过特异性设计药物激活的设计受体（DREADDs）的表达和激活来恢复内在STN活性，使皮质-基底神经节-丘脑-皮质环的活性正常化，并改善运动功能障碍。通过提出的培训计划，申请人将获得分子，电生理，解剖和行为技术方面的专业知识，并发展必要的分析和沟通技巧，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.