PREFRONTAL CORTEX NEUROPHYSIOLOGY AFTER CHRONIC COCAINE

描述：(申请人摘要) 可卡因成瘾继续成为我们最昂贵的社会和医疗成本之一 有问题。对可卡因成瘾机制的神经生物学研究已经 主要集中在中隔伏核的多巴胺(DA)系统。然而，我们已经知道 15年来，前额叶皮质(PFC)是可卡因 自我管理开始了。而且，新的证据表明 PFC的谷氨酸能锥体神经元也是诱导所必需的 可卡因致敏作用及其细胞相关性的研究。令人惊讶的是，我们知道 几乎没有关于可卡因如何改变PFC神经元的内容；事实上，我们非常了解 多巴胺对前额叶皮质神经生理特性的调节作用 锥体细胞。该提案描述了设计的一系列项目 为了填补我们知识中的这些空白，我们的长期目标是确定 可卡因敏化和线索诱导的细胞机制 戒断时对可卡因的渴求。更具体地说，我们的具体目标是 识别PFC中不同DA受体亚型调制的离子电流 锥体神经元，并在这些神经元的精确亚细胞成分上这样做 细胞。更重要的是，人们提议进行实验，以确定 反复给药可卡因改变了这些电导和它们的 通过特定的DA受体进行调节。 在目标1中，我们将使用来自AUTECH的全单元电压钳记录 分离的PFC神经元以确定哪些DA受体调节哪些特定的 电压门控钠电流、钙电流和钾电流。生物物理学和药理学 将使用程序来隔离特定的电流。选择性激动剂和 将使用D1和D2类DA受体的拮抗剂来识别这些 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类受体。在目标2中，我们将使用DUAL 体细胞、树突状全细胞和细胞附着性膜片钳方法的研究 PFC切片以确定Na和K电导的潜在差异，以及 它们受到DA的调节，在特定的微域中是神经元。此外, 我们将确定DA受体是否调制动作电位 反向传播作为一种选择特定树突突触的方法 依赖使用的可塑性。一旦我们确定了DA对特定疾病的影响 电导，我们会将自我注射可卡因的大鼠与 对每个电导的状态及其响应性的控制 对DA受体的刺激。我们相信，这些项目将孤立 细胞水平上的可卡因成瘾的关键因素 随着工作的进展，我们可能会确定可卡因成瘾导致 易感人群的适应不良反应。

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.