DYNAMIC PROPERTIES OF ION CHANNELS IN THE SUBTHALAMUS

谷氨酸能丘脑底核(STN)是正常自主运动和运动障碍(如帕金森病)时基底节神经元活动的主要驱动力。在特发性和实验性帕金森病模型中，STN神经元表现出异常的活动模式，部分原因可能是其固有的细胞膜属性发生了变化。STN的细胞可塑性可能是由于STN内多巴胺能神经调节的丧失和/或突触输入模式的改变，这是由于其他基底节核团中的多巴胺耗尽所致。第一个具体目的是进一步确定在体外STN神经元正常放电特性的离子、生物物理和分子原理，即自发振荡、驱动高频活动和反弹爆发式放电。这将使用STN的电流和电压钳位记录来实现 使用膜片钳技术的穿孔、全细胞和有核构型的神经元体外培养。特异性离子通道在放电行为中的作用将通过在选择性通道阻滞剂存在下的放电和离子电流的检查来阐明，STN神经元中离子通道的分子性质将通过α亚基的免疫细胞化学和信使RNA表达的研究来确定。第二个具体目标是确定多巴胺如何调节STN神经元的放电和离子通道特性。这将使用上面描述的电生理和分子相结合的方法来解决，多巴胺对离子通道的神经调节将使用选择性的D1样和D2样受体激动剂来确定。正常和多巴胺耗竭状态下STN神经元的膜特性 然后将对动物进行比较，以确定细胞可塑性是否导致帕金森病中STN神经元的异常活动。

The glutamatergic subthalamic nucleus (STN) is a major driving force of neuronal activity in the basal ganglia during normal voluntary movement and in movement disorders e.g. in Parkinson's disease (PD). In idiopathic and experimental models of PD, STN neurons display abnormal patterns of activity, which may arise, in part, from an alteration in their intrinsic membrane properties. Cellular plasticity in the STN may result from the loss of dopaminergic neuromodulation within the STN and/or the altered pattern of synaptic input, which results from the depletion of dopamine in other basal ganglia nuclei. The first specific aim is to determine further the ionic, biophysical and molecular principles that underlie the normal firing properties of STN neurons in vitro i.e., spontaneous oscillation, driven high-frequency activity and rebound burst firing. This will be achieved using current- and voltage-clamp recording of STN neurons in vitro using the perforated, whole-cell and nucleated configurations of the patch clamp technique. The roles of specific ion channels in firing behavior will be adressed by examination of firing and ionic currents in the presence of selective channel blockers, the molecular nature of ion channels in STN neurons will be determined using immunocytochemistry of alpha subunits and messenger RNA expression studies. The second specific aim is to determine how dopamine modulates the firing and ion channel properties of STN neurons. This will be addressed using the combined electrophysiological and molecular approach described above, the neuromodulation of ion channels by dopamine will be determined using selective D1-like and D2-like receptor agonists. The membrane properties of STN neurons in normal and dopamine-depleted animals will then be compared to determine whether cellular plasticity contributes to the abnormal activity of STN neurons in PD.