Synaptic Transmission, Plasticity and Integration in the Subthalamic Nucleus

描述（由申请人提供）：帕金森病（PD）的运动障碍、运动迟缓和僵硬等衰弱性运动症状与相互连接的gaba能外苍白球（GPe）和谷氨酸能丘脑下核（STN）以及相关的皮质-基底神经节-丘脑皮质网络中神经元活动的频率和模式的变化密切相关。在特发性和实验性PD中，GPe和STN分别表现出低活性和高活性，以及异常的同步，节律性，突发性放电。PD实验模型急性黑质多巴胺神经元丢失后，异常STN活性缓慢出现并逐渐增强，2-3周后达到稳定最大值。这一过程表明，细胞和网络特性的适应性变化有助于帕金森病STN活性的发展。由于GPe能有效调节STN活动的频率和同步，并能在STN中产生反弹爆发放电，因此我们采用电生理、分子和解剖学方法比较了GPe-STN在对照组和6-羟多巴胺损伤啮齿动物中的传递。这些研究表明，多巴胺缺失2-3周后，GPe-STN的投射通过突触连接的增殖而显著增强。因此，这种改变可能是PD中出现异常GPe-STN活性的主要原因。在这里，我们建议研究多巴胺缺失后GPe-STN传递改变的时间过程、性质、潜在机制和功能后果。我们建议应用细胞生理学测量GPe-STN突触功能和功能障碍；用解剖学方法确定GPe-STN突触可塑性的结构和分子基础；双光子激光扫描显微镜和光遗传学确定触发突触可塑性的Ca2+来源；病毒载体，分子和生化方法来定义潜在的分子机制，使我们能够操纵GPe-STN的传播。我们提出了四个具体目标：确定实验性PD中GPe-STN突触传递改变的时间和性质。我们假设GPe-STN传递的改变与帕金森病STN活性的发展有关；目标2。确定实验性PD中导致GPe-STN突触传递增强的触发因素。我们假设在实验性PD中，STN谷氨酸受体和/或Cav通道的过度激活导致GPe-STN突触传递增强；目标3。确定GPe-STN突触传递增强的细胞和分子机制。我们假设STN谷氨酸受体的过度活化和/或STN神经元的过度活化导致细胞内Ca2+的增加，这激活了介导突触增强和增殖的信号级联反应；目标4。确定慢性多巴胺耗竭对STN神经元动作电位依赖性抑制的影响。我们假设GPe-STN神经元的自主活动不会因多巴胺消耗而改变，并且GPe-STN的抑制作用通过GPe-STN连接的增强而增强。

DESCRIPTION (provided by applicant): The debilitating motor symptoms of akinesia, bradykinesia and rigidity in Parkinson's disease (PD) are intimately related to changes in the frequency and pattern of neuronal activity in the reciprocally connected GABAergic external globus pallidus (GPe) and glutamatergic subthalamic nucleus (STN) and associated cortico-basal ganglia-thalamocortical networks. In idiopathic and experimental PD the GPe and STN exhibit hypo- and hyperactivity, respectively, and abnormal synchronous, rhythmic, burst firing. Following acute loss of substantia nigra dopamine neurons in experimental models of PD abnormal STN activity emerges slowly and intensifies gradually until it reaches a stable maximum after 2-3 weeks. This process suggests that adaptive changes in cellular and network properties contribute to the development of parkinsonian STN activity. Because the GPe potently regulates the frequency and synchronization of STN activity and can generate rebound burst firing in the STN, GPe-STN transmission was compared in control and 6-hydroxydopamine-lesioned rodents using electrophysiological, molecular and anatomical approaches. These studies revealed that 2-3 weeks after loss of dopamine the GPe-STN projection had strengthened considerably through proliferation of synaptic connections. This alteration could therefore be a major contributor to the emergence of abnormal GPe-STN activity in PD. Here we propose to study the timecourse, nature, underlying mechanisms and functional consequences of alterations in GPe-STN transmission that follow the loss of dopamine. We propose to apply cellular physiology to measure GPe-STN synaptic function and dysfunction; anatomical approaches to define the structural and molecular bases of GPe-STN synaptic plasticity; 2-photon laser scanning microscopy and optogenetics to define the sources of Ca2+ that trigger synaptic plasticity; viral vector, molecular and biochemical approaches to define the underlying molecular mechanisms and enable us to manipulate GPe-STN transmission. We propose 4 Specific Aims: Aim 1. Determine the timecourse and nature of alterations in GPe-STN synaptic transmission in experimental PD. We hypothesize that alterations in GPe-STN transmission are correlated with the development of parkinsonian STN activity; Aim 2. Determine the triggers leading to potentiation of GPe-STN synaptic transmission in experimental PD. We hypothesize that hyperactivation of STN glutamate receptors and/or Cav channels leads to the potentiation of GPe-STN synaptic transmission in experimental PD; Aim 3. Determine the cellular and molecular mechanisms underlying the potentiation of GPe-STN synaptic transmission. We hypothesize that hyperactivation of STN glutamate receptors and/or hyperactivity of STN neurons leads to an increase in intracellular Ca2+, which activates signaling cascades that mediate synaptic potentiation and proliferation; Aim 4. Determine the impact of chronic dopamine depletion on action potential-dependent inhibition of STN neurons. We hypothesize that the autonomous activity of GPe-STN neurons is not altered by dopamine depletion and that GPe-STN inhibition is increased through potentiation of GPe-STN connectivity. PUBLIC HEALTH RELEVANCE: In Parkinson's disease a small brain region called the subthalamic nucleus exhibits a characteristic, abnormal pattern of activity, which if corrected by medication or deep brain electrical stimulation greatly improves movement. The emergence of this abnormal pattern of activity is associated with alterations to the inputs of the subthalamic nucleus. We propose to study the mechanisms underlying these alterations and to determine whether they can be prevented for therapeutic benefit.