Do Cocaine and Chronic Stress Converge in the Basolateral Amygdala?

描述(由申请人提供)：治疗可卡因成瘾的一个主要挑战是戒毒者复发的倾向。复发的两个重要诱因是与既往吸毒和应激生活事件有关的线索。在博士后培训期间，我研究了伏隔核(NAC)中支持线索诱导的可卡因渴求依赖戒断强化(孵化)的机制。作为一名私人助理，我会把慢性压力的影响融入到我的学习中。到目前为止，大多数研究应激诱发复发易感性的研究都考察了急性应激源对恢复先前消除的寻求毒品行为的影响，这一模型可能不能准确地描述吸毒者的情况，他们通常不接受戒毒训练，并且可能在长时间戒毒后复发。因此，迫切需要动物模型来探索慢性应激和药物戒断对线索诱导的可卡因渴求的影响之间的相互作用。为了满足这一需求，我将使用上述的“可卡因渴求潜伏期”模型来研究戒断期间的慢性应激对复发易感性的影响，在该模型中，线索诱导的大鼠寻求药物的行为在大鼠戒断长期接触药物自我给药的最初几个月中逐渐加剧。通过将我长期以来对成瘾的兴趣与我对应激神经生物学的新兴趣结合起来，我开发了一个独立于导师研究的研究项目，并将使我能够追求三个长期目标：开发对成瘾具有更好表面有效性的动物模型，使用保存神经元回路并使细胞和行为结果相互关联的体内模型，以及最终为药物疗法的开发做出贡献，以帮助正在康复的成瘾者维持戒除。这项研究计划，以及我与我的导师(Marina Wolf博士)和共同导师(J.Amiel Rosenkranz博士和Janice Urban博士)共同制定的培训计划，将使我能够实现成为学术环境中的独立研究员的职业目标。我的项目借鉴了我的同事们之前在杏仁基底外侧核(BLA)方面的研究成果，这是对压力做出行为反应的关键区域。罗森克兰兹博士的实验室表明，慢性压力会增强大脑白质层的兴奋性驱动力，而厄本博士的实验室则发现，反复激活大脑白质层中的NPY受体可以产生持久的压力弹性。此外，董实验室最近的工作(2013)表明，从BLA到NAC的谷氨酸投射对于孵化线索诱导的可卡因寻找的表达至关重要。结合这些工作，我的中心假设是，可卡因戒断和慢性应激暴露会产生BLA神经元活动的协同增加，从而促进渴望的孵化，而促进应激适应能力的治疗将通过在BLA产生相反的神经适应来阻止这种促进。我的初步数据显示，戒除过程中的慢性食物限制压力实际上确实加速了对可卡因的渴望的孵化。在目标1(K99)中，我将确定这一效应的持久性，以及它是否概括为重复束缚应激，重复束缚应激是许多先前关于BLA的研究中使用的应激形式。在目标2(K99/R00)中，我将通过比较大鼠的内在兴奋性、突触传递和BLA神经元的形态特征来验证我的假设，即可卡因戒断和应激在BLA中起协同作用。大鼠在戒断过程中接受重复应激或对照条件。在目标3(K99/R00)中，我将确定BLA中NPY受体的激活是否反对慢性应激诱导的促进可卡因孵育的寻求，并使用生化方法来确定BLA中NPY信号介导这些保护作用的机制。在我之前的培训中，我获得了个人的博士后和博士后NRSA资助，发表在高影响力的期刊上，并获得了行为和生化方法方面的专业知识。然而，为了进行我提议的实验，我需要接受电生理学和应激模型方面的培训，以及独立所需的非长凳技能方面的更多经验。为了实现这些目标，我组建了一支杰出的顾问团队。我的主要导师沃尔夫博士是可卡因诱导的神经元可塑性方面的专家，他将监督我的培训。罗森克兰兹博士(共同导师)使用电生理学方法研究压力对杏仁核情感行为和生理的影响。他将训练我在体内对BLA神经元进行细胞内记录，然后评估它们的形态。厄本博士(共同导师)是一名神经内分泌学家，研究杏仁核中有助于抗压能力的适应。她将提供压力恢复模型和NPY信号的培训。我还将接受一个研究委员会的指导，该委员会由我的导师、共同导师以及我校的另外两位电生理学家曾桂源博士和安东尼·韦斯特博士组成。所有这些人都有很强的协作互动历史。我们共同制定了一个培训计划，利用与导师的定期个人会议、研究委员会每两年举行一次的会议、课程作业(包括研讨会和期刊俱乐部)以及机构博士后发展计划来发展我从博士后研究员过渡到学术环境中的独立研究员所需的非板凳技能。这一培训计划得到了一个出色的机构环境的加强，该环境提供了一流的设施，并在协作和支持的环境中集中了成瘾研究人员。

DESCRIPTION (provided by applicant): A major challenge for treating cocaine addiction is the propensity for abstinent users to relapse. Two important triggers for relapse are cues associated with prior drug use and stressful life events. During my postdoctoral training, I studied mechanisms in the nucleus accumbens (NAc) underlying the withdrawal-dependent intensification (incubation) of cue-induced cocaine craving. As a PI, I will incorporate the effect of chronic stress into my studies. To date, the majority of studies investigating stress-induced relapse vulnerability have examined the effects of acute stressors on the reinstatement of previously extinguished drug seeking behavior, a model which may not accurately depict the situation of addicts, who typically do not undergo extinction training and who may relapse after a long drug-free period. Thus, there is an urgent need for animal models that explore interactions between the effects of chronic stress and drug withdrawal on cue-induced cocaine craving. To address this need, I will study the effect of chronic stress during abstinence on relapse vulnerability using the 'incubation of cocaine craving' model mentioned above, in which cue-induced drug seeking in rats progressively intensifies during the first months of withdrawal from extended-access drug self-administration. By combining my long-standing interest in addiction with my emerging interest in the neurobiology of stress, I have developed a research program that will be independent of my Mentor's research and will allow me to pursue three long-term goals: developing animal models with better face validity for addiction, using in vivo models which preserve neuronal circuits and enable correlation of cellular and behavioral results, and ultimately contributing to development of pharmacotherapies to help recovering addicts maintain abstinence. This Research Plan, along with the Training Plan I have developed with my Mentor (Dr. Marina Wolf) and co- Mentors (Dr. J. Amiel Rosenkranz and Dr. Janice Urban), will enable me to achieve my career goal of becoming an independent researcher in an academic setting. My project draws on previous work from my co-Mentors on the basolateral amygdala (BLA), a critical region for behavioral responses to stress. Dr. Rosenkranz's lab has shown that chronic stress enhances excitatory drive in the BLA, while Dr. Urban's lab has found that repeated activation of NPY receptors in the BLA produces long-lasting stress resilience. Furthermore, recent work from the Dong lab (2013) has shown that glutamate projections from the BLA to the NAc are critical for the expression of incubated cue-induced cocaine seeking. Combining these lines of work, my central hypothesis is that cocaine withdrawal and chronic stress exposure produce a synergistic increase in BLA neuronal activity which facilitates incubation of craving, whereas treatments promoting stress resilience will prevent this facilitation by producing opposing neuroadaptations in the BLA. My preliminary data show that chronic food restriction stress during withdrawal does in fact accelerate the incubation of cocaine craving. In Aim 1 (K99), I will determine the persistence of this effect and whether it generalizes to repeated restraint stress, the form of stress used in many prior studies of the BLA. In Aim 2 (K99/R00), I will test my hypothesis that cocaine withdrawal and stress exert synergistic effects in the BLA by comparing intrinsic excitability, synaptic transmission, and morphological features of BLA neurons of rats that self-administer saline or cocaine and then either undergo repeated stress or control conditions during withdrawal. In Aim 3 (K99/R00), I will determine if NPY receptor activation in the BLA opposes the chronic stress-induced facilitation of incubation of cocaine seeking and employ biochemical methods to identify mechanisms in the BLA through which NPY signaling mediates these protective effects. During my prior training, I secured individual pre- and postdoctoral NRSA funding, published in high impact journals, and gained expertise in behavioral and biochemical approaches. However, to undertake my proposed experiments, I need training in electrophysiology and stress models, as well as more experience with non-bench skills required for independence. To accomplish these goals, I have put together an exceptional team of advisors. My Primary Mentor Dr. Wolf is an expert in cocaine-induced neuronal plasticity who will oversee my training. Dr. Rosenkranz (co-Mentor) uses electrophysiological approaches to study the effects of stress on affective behavior and physiology of the amygdala. He will train me to conduct in vivo intracellular recordings in BLA neurons and then assess their morphology. Dr. Urban (co-Mentor) is a neuroendocrinologist who studies adaptations in the amygdala contributing to stress resilience. She will provide training on models of stress resilience and NPY signaling. I will also be guided by a Research Committee composed of my Mentor, co-Mentors, and two other electrophysiologists at my University, Drs. Kuei-Yuan Tseng and Anthony West. All of these individuals have a strong history of collaborative interactions. Together, we have developed a Training Plan that utilizes regular individual meetings with Mentors, bi-annual meetings of the Research Committee, coursework (including seminars and journal clubs), and an institutional postdoctoral development program to develop the non-bench skills needed for my transition from a postdoctoral fellow to an independent investigator in an academic setting. This training plan is strengthened by an outstanding institutional environment offering excellent facilities and a concentration of addiction researchers in a collaborative and supportive setting.