The role of nucleus accumbens dopamine in incubation of cocaine craving

项目摘要 在治疗物质使用障碍患者时，复发是一个一贯的临床问题。至 为此，我将利用孵化渴求模型来研究多巴胺在伏隔核中的作用 (Nac)核心区(NAcc)在线索诱导的大鼠持久可卡因渴求中的作用 禁欲。这一过程始于大鼠自我注射可卡因，在此过程中，大鼠学习 将药物注射与灯光信号联系在一起。这之后是一段强制禁欲的时期，在此期间 老鼠被放回家中的笼子里，不会接触到药物或与药物配对的线索。在不同的时间点 在此禁欲期间，大鼠被返回到操作盒进行线索诱导的寻找测试，在此期间， 在以前传递药物和线索的鼻孔上做出反应，现在只传递线索。作为 禁欲持续时间增加，在这些条件下做出反应，我们对线索诱导的药物寻求的衡量标准 或渴望，逐渐加剧或‘孵化’。该模型在翻译上是相关的，因为 渴望也会发生在人类身上。沃尔夫实验室和其他实验室已经证明，孵化需要 NAcc中的兴奋性突触传递允许这些突触的加强。然而，尽管 多巴胺能信号在NAcc中对动机行为的重要性，人们对其作用知之甚少 多巴胺在可卡因渴求的孵化过程中发挥了作用。我假设多巴胺在NAcc中短暂存在 与线索诱导的药物寻找相关，在孵化过程中增强，并有助于其表达。在目标1中， 我将使用光纤光度法与多巴胺生物传感器Grab_DA配对来测量多巴胺的反应 在早期禁欲、孵化前和晚期禁欲的寻找测试中，受到药物配对线索的刺激， 在孵化达到平台期后。在目标2中，我将确定NAcc多巴胺能神经元的功能意义 在寻找药物前向NAcc注射多巴胺受体拮抗剂在孵化期间的传播 测试。我预测，阻断D1多巴胺受体或D2多巴胺受体都会减少线索诱导的 已经发生了孵化后寻找可卡因的情况，这种减少在早期戒除中将不那么强劲。 这个项目将解决目前文献中关于多巴胺在欲望孵化中的作用的一个空白。在……里面 除了科学进步，这项建议还为我提供了许多作为科学家发展的机会。学习 纤维光度学和本项目所需的其他方法，并将这些方法应用于 已建立的复发动物模型，是我在未来可以建立的关键基础技术技能 博士后培训。这次团契培训的其他目标是提高我的书面和口头交流能力。 通过撰写手稿和参加会议介绍我在 神经科学，以提高我设计严谨实验的能力，并获得更多指导经验 并监督其他人。这些技能将帮助我成为一名有竞争力的博士后候选人，并最终 请允许我成为一名独立研究员，无论是PI级别的还是工作人员科学家级别的。

Project Summary Relapse represents a consistent clinical problem when treating individuals with Substance Use Disorder. To study this, I will use the incubation of craving model to investigate the role of dopamine in the nucleus accumbens (NAc) core subregion (NAcc) in the persistence of cue-induced cocaine craving in rats after protracted abstinence. The procedure begins with extended access cocaine self-administration during which the rat learns to associate a drug infusion with a light cue. This is followed by a period of forced abstinence during which the rat is returned to their home cage and has no exposure to the drug or drug-paired cues. At different time-points during this abstinence period, rats are returned to the operant boxes for cue-induced seeking tests, during which responding on the nose-poke hole that previously delivered drug and cue now delivers only the cue. As the duration of abstinence increases, responding under these conditions, our measure of cue-induced drug seeking or craving, progressively intensifies or ‘incubates’. This model is translationally relevant because incubation of craving also occurs in humans. The Wolf lab and others have demonstrated that incubation requires plasticity of excitatory synaptic transmission in the NAcc allowing for a strengthening of these synapses. However, despite the importance of dopaminergic signaling in the NAcc for motivated behavior, little is known about the role that dopamine plays in the incubation of cocaine craving. I hypothesize that dopamine transients in the NAcc associated with cue-induced drug seeking intensify during incubation and contribute to its expression. In Aim 1, I will use fiber photometry paired with the dopamine biosensor GRAB_DA to measure dopamine responses provoked by the drug paired cue during seeking tests in early abstinence, prior to incubation, and late abstinence, after incubation has plateaued. In Aim 2, I will determine the functional significance of NAcc dopaminergic transmission during incubation by injecting dopamine receptor antagonists into the NAcc before the drug seeking test. I predict that blockade of either D1 dopamine receptors or D2 dopamine receptors will reduce cue-induced cocaine seeking after incubation has occurred, and that this reduction will be less robust in early abstinence. This project will address a current gap in the literature regarding dopamine’s role in the incubation of craving. In addition to scientific advancement, this proposal offers me many opportunities to develop as a scientist. Learning fiber photometry and the other approaches required for this project, and applying these approaches to an established animal model of relapse, are key foundational technical skills that I can build upon during future postdoctoral training. Other goals of this fellowship training are to improve my written and oral communication skills by writing manuscripts and by attending conferences to present my work and network in the field of neuroscience, to improve my ability to design rigorous experiments, and to gain more experience with mentoring and supervising others. These skills will help me become a competitive post-doc candidate and will eventually allow me to become an independent researcher either at the PI level or the staff scientist level.