CNS DA NEURONS--CELLULAR BASIS OF PATTERNED ACTIVITY

描述(摘自申请者摘要)：这是一份重新提交的修改后的申请，延长了作为我们之前资助的第一个奖项的一部分完成的工作。这项建议中概述的研究集中在对中脑多巴胺神经元所表现出的复杂活动模式产生的离子机制的研究。这些研究的合理性来自大量文献，这些文献表明，多巴胺细胞放电模式的变化代表了这些细胞改变其对前脑目标神经元的影响的机制。本申请中提出的实验的主要目标被组织为三个特定目标。首先，将使用细胞内和细胞外记录技术来识别和表征负责在多巴胺神经元中产生爆发活动的离子机制。这些实验将建立我们实验室建立的体外模式活动模型，并将重点描述电压门控钙通道和兴奋性氨基酸受体在产生平台式振荡的膜电位中的作用，这种振荡似乎驱动这些神经元的爆发性活动。在第二个具体目标中，电流和电压钳技术将被用来检验如下假设：(1)有助于终止爆发振荡的平台期的超极化；(2)通过促进脉冲频率适应的机制来调节爆发内脉冲的时间组织。在第三个也是最终的目标中，我们将使用多学科的方法，包括分子和电生理学方法来检验这一假说，即APamin敏感的钙激活的K+通道功能表达的增加是导致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，我们希望获得关于DA相关疾病的病因病理基础和用于治疗这些疾病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.