Cocaine-Induced Dopamine Transporter Changes are Reversed by Amphetamine

描述（由申请人提供）：在美国，可卡因（COC）依赖是一个主要的健康问题，目前还没有批准的药物治疗来帮助治疗。成瘾研究中使用的啮齿动物模型的“黄金标准”是COC自我给药。我们已经使用该模型表明，长期暴露于COC导致多巴胺转运蛋白（DAT）的药效学耐受性。DAT对COC的耐受性是我们实验室发现的一个相对较新的现象，这为COC耐受性的操纵开辟了一条新的研究途径，我们将在本提案中进行探索。我们发现，单次注射AMPH（0.56 mg/kg IV）可迅速并完全逆转DAT时的COC耐受性，甚至导致COC效力增加至对照水平以上。具体目标包括表征和扩展这一发现的实验。在具体目标1中，我们将探索AMPH的最低有效剂量，可导致DAT可塑性逆转以及这种作用的时间过程。虽然这种表征是非常重要的，我们主要感兴趣的是发现DAT的结构和功能的变化，负责这种效果。因此，对于具体目标2，我们将在结构上使用 不同的DA释放剂和具有不同DAT亲和力的阻断剂代替AMPH推注，并使用切片伏安法来探索COC效力和突触前DA功能（释放和摄取）对这些化合物的响应。此外，我们感兴趣的是我们的神经化学数据的行为含义。在具体目标3中，我们将在自我给药和AMPH推注前后对动物进行测试，并进行运动评估，而另一组将按照COC自我给药的渐进比例方案进行评估。 虽然我们的兴趣主要是在基本药理学驱动DAT的变化，这可能是相关的文献提出DAT释放剂，如AMPH作为假定的COC成瘾药物治疗。 尽管COC成瘾的激动剂疗法存在争议，但我们可能能够定义其某些治疗作用的假定机制，这可能会推动此类疗法的更多合理设计。

DESCRIPTION (provided by applicant): Cocaine (COC) dependence in the United States is a major health problem that currently has no approved pharmacological therapies to help in treatment. The "gold standard" of rodent models used in addiction research is COC self-administration. We have used this model to show that extended exposure to COC results in a pharmacodynamic tolerance of the dopamine transporter (DAT). Tolerance of the DAT to COC is a relatively new phenomenon discovered by our lab, which opened up a new avenue of research into the manipulation of COC tolerance, which we will explore in this proposal. We found that administration of a single AMPH bolus (0.56 mg/kg IV) rapidly and completely reversed the COC tolerance at the DAT, and even caused COC potency to increase above control levels. The specific aims include experiments that characterize and expand on this discovery. In Specific Aim 1 we will explore the lowest effective dose of AMPH that can cause a reversal of DAT plasticity and the time course of this effect. Although this characterization is quite important, we are primarily interested in discovering the structural and functional changes in the DAT that are responsible for this effect. Thus, for Specific Aim 2, we will use structurally different DA releasers and blockers with different DAT affinities in place of an AMPH bolus and use slice voltammetry to explore COC potency and presynaptic DA function (release and uptake) in response to these compounds. Additionally, we are interested in the behavioral implications for our neurochemical data. In Specific Aim 3 we will test animals before and after self-administration and an AMPH bolus with locomotor assessments while another group will be assessed on a progressive ratio schedule of COC self-administration. While our interest is primarily in the basic pharmacology driving the DAT changes, this may be relevant to the literature proposing DAT releasers such as AMPH as putative COC addiction pharmacotherapies. Although agonist therapies for COC addiction are controversial, we may be able to define a putative mechanism for some of their therapeutic effects which could potentially drive more rationale design of such therapies.