CaV 1.3 L-type Calcium Channel Mechanisms in Cocaine Seeking

描述(由申请人提供)：成功治疗可卡因成瘾的一个主要障碍是在戒毒期间发生的高复吸率。暴露于与毒品相关的线索可导致可卡因复发，这些线索会导致对可卡因的渴望和寻找可卡因的行为。然而，到目前为止，还没有FDA批准的治疗可卡因成瘾的药物疗法。因此，我们必须了解可卡因寻找行为的神经生物学机制，以便能够确定新的治疗靶点来预防这种复发障碍。药物相关的线索引起腹侧被盖区(VTA)多巴胺(DA)神经元的爆发式放电，导致伏核(NAC)的DA时相释放。我们实验室的工作表明，VTA到NAC回路中的时相DA活动以及VTA胆碱能受体对这种活动的调节，对于线索诱导的可卡因寻找是至关重要的。然而，在可卡因戒断过程中，调节时相性多巴胺释放和线索诱导的药物寻找行为的确切机制仍然知之甚少。我们先前已经证明，VTA DA神经元中的Cav1.3 L型钙通道(LTCCs)及其下游的钙激活通路在长时间戒断后对可卡因的敏化精神运动行为反应中起关键作用。此外，我们最近的发现表明，Cav1.3通道促进DA神经元从紧张性放电到爆发性放电的转变，并通过胆碱能机制发挥作用，强烈表明Cav1.3通道的重新招募可能是线索诱导的可卡因寻找行为的基础。因此，R21应用的目标是测试VTA Cav1.3机制通过调节NAC中DA的相性释放来支持线索诱导的可卡因寻找行为的假设。为了实现这一目标，我们将使用一种创新的综合实验方法，使用临床前自我给药大鼠模型，使用药理学和病毒载体介导的VTA中的基因敲除，结合NAC中的行为测试和体内伏安测定，来研究线索诱导的戒断过程中的可卡因寻找。在特定的目标1中，我们将研究VTA Cav1.3通道在线索诱导的可卡因寻找中的作用。在特定的目标2中，我们将在体内研究VTA Cav1.3通道在VTA诱发的和乙酰胆碱受体介导的NAc在早期和长期戒断时相DA释放中的作用。从这项研究中获得的机制洞察力将为药物复发的神经生物学提供新的理解，并将确定Cav1.3通道是否可能作为预防可卡因复发的潜在新的治疗靶点。

DESCRIPTION (provided by applicant): A major barrier to successfully treating cocaine addiction is the high rate of drug relapse that occurs during periods of drug withdrawal. Cocaine relapse can be precipitated by exposure to drug-associated cues that induce cocaine craving and cocaine-seeking behavior. However, to date there are no FDA approved pharmacotherapies to treat cocaine addiction. Thus it is crucial that we understand the neurobiological mechanisms of cocaine-seeking behavior to be able to identify novel therapeutic targets to prevent this relapsing disorder. Drug-associated cues evoke burst firing of ventral tegmental area (VTA) dopamine (DA) neurons that results in phasic DA release in the nucleus accumbens (NAc). Work from our laboratory has revealed that phasic DA activity in the VTA to NAc circuit, and VTA cholinergic receptor regulation of such activity, is critical for cue-induced cocaine-seeking. However, the precise mechanisms that mediate phasic dopamine release and cue-induced drug-seeking behavior during cocaine withdrawal remain poorly understood. We have previously shown that Cav1.3 L-type Ca2+ channels (LTCCs) and their downstream Ca2+-activated pathways in VTA DA neurons are critical for sensitized psychomotor behavioral responses to cocaine following periods of prolonged withdrawal. Additionally our recent findings have revealed that Cav1.3 channels facilitate the transition of DA neurons from tonic to burst firing and act through cholinergic mechanisms, strongly suggesting that recruitment of Cav1.3 channels may underlie cue-induced cocaine-seeking behavior. Thus, the goal of this R21 application is to test the hypothesis that VTA Cav1.3 mechanisms underlie cue-induced cocaine-seeking behavior by regulating phasic DA release in the NAc. To achieve this goal, we will use an innovative and integrative experimental approach using pharmacology and viral vector-mediated genetic knockdown in the VTA in combination with behavioral testing and in vivo voltammetry in the NAc, to examine cue-induced cocaine seeking during withdrawal, using the preclinical self-administration rat model. In specific aim 1, we will examine the role of VTA Cav1.3 channels in cue-induced cocaine-seeking during early and protracted withdrawal. In specific aim 2, we will examine in vivo the role of VTA Cav1.3 channels in VTA-evoked- and acetylcholine receptor-mediated phasic DA release in the NAc during early and protracted withdrawal. The mechanistic insight gained from this study will provide new understanding of the neurobiology of drug relapse and will determine whether Cav1.3 channels may serve as a potential novel therapeutic target to prevent cocaine relapse.