CNS DA NEURONS--CELLULAR BASIS OF PATTERNED ACTIVITY

描述（从申请人的摘要）：这是一个修改后的应用程序，延长我们以前资助的第一个奖项的一部分完成的工作重新提交。在这项建议中概述的研究集中在中脑多巴胺神经元表现出的复杂活动模式的产生所涉及的离子机制的调查。这些研究的理由来自大量文献，表明多巴胺细胞放电模式的改变代表了这些细胞改变其对前脑靶神经元影响的机制。本申请中提出的实验的主要目的被组织成三个具体目标。在第一，内和细胞外记录技术将被用来识别和表征负责产生多巴胺神经元的爆发活动的离子机制。这些实验将使我们在我们的实验室开发的体外模式的活动模型，并将重点描绘的作用，电压门控钙2，通道和兴奋性氨基酸受体在产生平台样振荡的膜电位，似乎驱动这些神经元的爆发活动。在第二个具体目标中，将使用电流和电压钳技术来检验以下假设：apamin不敏感的Ca2+依赖性电导：（1）有助于终止爆发振荡的平台期的超极化，以及（2）通过促进尖峰频率适应的机制来调节爆发内尖峰的时间组织。在第三个也是最后一个目标中，将使用涉及分子和电生理学方法的多学科方法来检验以下假设：apamin敏感性Ca 2+激活的K+通道的功能表达的增加是体外正常活动模式丧失的原因。通过更清楚地了解这些基本的生理机制，我们希望获得有关DA相关疾病的病因病理学基础和用于治疗它们的药物的相关药理作用的更多见解。

DESCRIPTION (from applicant's abstract): This is a resubmission of a revised application that extends work completed as part of our previously funded FIRST Award. The research outlined in this proposal centers on an investigation of the ionic mechanisms involved in generation of the complex activity patterns exhibited by mesencephalic dopamine neurons. The rational for these studies derives from an extensive literature indicating that alterations in dopamine cell firing pattern represent a mechanism through which these cells alter their influence on target neurons in the forebrain. The principal objectives of the experiments proposed in this application are organized into three specific aims. In the first, intra- and extracellular recording techniques will be used to identify and characterize the ionic mechanisms responsible for generating bursting activity in dopamine neurons. These experiments will make us of an in vitro model of patterned activity developed in our laboratory and will focus on delineating the role of voltage-gated Ca 2, channels and excitatory amino acid receptors in generating the plateaulike oscillations in membrane potential that appear to drive bursting activity in these neurons. In the second specific aim, current and voltage clamp techniques will be used to test the hypothesis that an apamin-insensitive Ca2+-dependent conductance: (1) contributes to the hyperpolarization that terminates the plateau phase of the bursting oscillation and (2) regulates the temporal organization of spikes within bursts by contributing to the mechanism underlying spike frequency adaptation. In the third and final aim, a multidisciplinary approach, involving both molecular and electrophysiological approaches will be used to test the hypothesis that an increase in the functional expression of apamin-sensitive Ca2"-activated K+ channels is responsible for the loss Of normal activity patterns in vitro. By more clearly understanding these basic physiological mechanisms, we hope to gain additional insights regarding the etiopathological basis of DA related disorders and the relevant pharmacological actions of the drugs used to treat them.