PREFRONTAL CORTEX NEUROPHYSIOLOGY AFTER CHRONIC COCAINE

描述：（申请人摘要） 可卡因成瘾仍然是我们最昂贵的社会和医疗之一 问题对可卡因成瘾机制的神经生物学研究 主要集中在中脑多巴胺（DA）系统。然而，我们已经知道， 前额叶皮层（PFC）是可卡因的部位， 开始自我管理。新的证据表明， 前额叶皮层的多巴胺能锥体神经元也是诱导的必要条件 可卡因致敏性及其细胞相关性。令人惊讶的是，我们知道 几乎没有关于可卡因如何改变PFC神经元的信息;事实上，我们非常了解 关于DA如何调节PFC的神经生理学特性， 锥体细胞该提案描述了一系列项目， 为了填补我们知识上的这些空白， 负责可卡因致敏和线索诱发的细胞机制 戒断期间对可卡因的渴望更具体地说，我们的具体目标是 识别PFC中不同DA受体亚型调节的离子电流 锥体神经元，并在精确的亚细胞成分， 细胞更重要的是，实验提出，然后确定如何 重复的可卡因自我给药改变了这些电导， 通过特定的DA受体调节。 在目标1中，我们将使用急性心肌梗死的全细胞电压钳记录， 分离的PFC神经元，以确定哪些DA受体调节哪些特异性 电压门控Na+、Ca 2+和K+电流。生物物理学和药理学 将使用程序来隔离特定电流。选择性激动剂和 D1和D2类DA受体的拮抗剂将用于鉴定这些受体。 受体和受体敲除小鼠（D1、D2、D4、D5）将用于 区分这些类别中的每一个的受体。在目标2中，我们将使用dual 体细胞和树突状全细胞和细胞贴附膜片钳方法， PFC切片，以确定Na+和K+电导的电位差，以及 在神经元的特定微区中，它们受到DA的调节。此外，本发明还提供了一种方法， 我们将确定DA受体是否调节动作电位 反向传播作为选择特定树突突触的手段， 使用依赖的可塑性。一旦我们确定了DA对特定的 电导，我们将比较大鼠有自我管理的可卡因， 关于每个电导的状态及其响应性的控制 多巴胺受体刺激。我们相信这些项目将隔离 可卡因成瘾的关键因素在细胞水平上， 工作进展，我们可以确定可卡因成瘾导致 易感个体的适应不良反应。

DESCRIPTION: (Applicant's Abstract) Cocaine addiction continues as one of our most costly social and medical problems. Neurobiological research into the mechanisms of cocaine addiction has focused primarily on the mesoaccumbens dopamine (DA) system. Yet, we have known for 15 years that the prefrontal cortex (PFC) is the site where cocaine self-administration is initiated. And, new evidence indicates that glutamatergic pyramidal neurons of the PFC are also necessary for the induction of cocaine sensitization and its cellular correlates. Surprisingly, we know almost nothing about how cocaine alters PFC neurons; indeed, we know very little about how DA modulates the neurophysiological properties of PFC pyramidal cells. This proposal describes a series of projects that are designed to fill these gaps in our knowledge with the long-term objective of identifying the cellular mechanisms responsible for cocaine sensitization and cue-elicited cocaine craving during withdrawal. More specifically, our specific goal is to identify the ion currents modulated by different DA receptor subtypes in PFC pyramidal neurons and to do so at precise sub-cellular components of these cells. More importantly, experiments are proposed to then determine how repeated cocaine self-administration alters these conductances and their modulation by specific DA receptors. In Aim 1, we will use whole cell voltage-clamp recordings from acutely dissociated PFC neurons to identify which DA receptors modulate which specific voltage gated Na+, Ca2+, and K+ currents. Biophysical and pharmacological procedures will be used to isolate specific currents. Selective agonists and antagonists for D1 and D2 class DA receptors will be used to identify these receptors, and receptor knockout mice (Dl, D2, D4, D5) will be used to distinguish receptors within each of these classes. In Aim 2, we will use dual somatic and dendritic whole-cell and cell-attached patch clamp methods in slices of PFC to identify potential differences in Na+ and K+ conductances, and their modulation by DA, within specific microdomains the neurons. In addition, we will determine whether DA receptors modulate action potential backpropagation as a means of selecting specific dendritic synapses for use-dependent plasticity. Once we have identified the effects of DA on specific conductances, we will compare rats that have self-administered cocaine to controls with respect to the state of each conductance and its responsiveness to DA receptor stimulation. We believe that these projects will isolate critical elements of cocaine addiction at a cellular level and that, as this work progresses, we may identify means by which cocaine addiction leads to maladaptive responses in susceptible individuals.