Synaptic Mechanisms of Addiction-Related Behaviors in the Nucleus Accumbens

描述（由申请人提供）：在我作为科学家的职业生涯早期，我认为交流是所有生物过程的关键。这种意识形态已经演变成对突触传递研究的浓厚兴趣。在Danny G. Winder博士的实验室里，我开始了突触生理学的训练，发表了许多关于代谢性谷氨酸受体调节兴奋性突触传递及其体内可卡因募集的论文。在我的博士后培训期间，我在Robert C. Malenka, m.d., Ph.D.的实验室继续研究奖赏相关电路中的突触传递。Malenka博士是一位著名的突触生理学家，培养了许多在突触生理学和成瘾领域的杰出人物，Antonello Bonci (NIDA), Karl deisserth（斯坦福大学），Dan Feldman（加州大学伯克利分校），Pablo Castillo（阿尔伯特·爱因斯坦），John Isaac (NIH，现在的Lilly), Anatol Kreitzer (UCSF), Michael Crair（耶鲁大学），马克·托马斯（明尼苏达大学）等等。我的目标是通过在学术界获得一个独立的实验室来继续这一传统，研究突触传递在奖励和厌恶行为中的作用。我的研究领域与Malenka博士的不同之处在于，除了兴奋性传递外，我还对NAc中间神经元以及初级输出神经元的抑制性和神经调节传递感兴趣。最终，我计划扩展疾病模型，研究急性和慢性疼痛等厌恶状态对NAc突触回路的影响。为了做到这一点，我正在利用最先进的技术和复杂而简单的方法来解决伏隔核（NAc）的这些问题。该项目的最终目标是更好地了解NAc回路中的突触功能，并开始解决这些回路是如何被招募来引发成瘾相关行为的。NAc作为中脑边缘多巴胺系统的一部分，整合了兴奋性、抑制性和调节性输入的复杂组合，以优化适应性动机行为。突触传递的动态改变与成瘾性疾病的发展和表达密切相关。具体目标包括使用体外切片的全细胞记录来定义NAc神经元的基本特性以及体内可卡因暴露如何改变这些特性。本研究将利用细菌人工染色体（BAC）转基因标记小鼠来描述体内可卡因暴露对NAc输出神经元和局部微回路中间神经元（INs）突触特性的影响，这些标记小鼠可以特异性标记直接和间接途径的中棘神经元（MSNs）、gaba能和胆碱能INs。此外，NAc、msn和INs上三种不同兴奋性输入的突触特性将被表征，体内可卡因体验对这些特定输入的影响将通过病毒表达通道视紫红质（ChR2）来确定。本提案指导阶段的目标是：(1)检查体内可卡因体验后直接和间接msn的突触特性，(2)利用光遗传学方法确定体内可卡因体验后，对这些msn的特定兴奋性突触输入是否会发生差异改变。独立阶段将涉及：(1)NAc INs的传入特异性基础和药物诱导的兴奋性突触特性的改变，(2)INs和msn之间突触连通性的基础和药物诱导的改变，以及(3)药物相关背景下NAc INs的光诱导（ChR2）激活的行为影响，所有这些都利用最先进的光遗传学方法。本实验的结果将为NAc突触回路在病理生理状态下的变化提供基础知识，并对成瘾相关行为的未来治疗目标具有指导意义。此外，本研究的细致方法为研究其他药物滥用和成瘾模型以及NAc中与适应不良过程相关的其他肯定性障碍提供了基础。我期望在完成导师的项目后，我将拥有在一所受人尊敬的高等学府成功运营自己独立实验室的技术和知识专长。我将开发工具，在会议和出版物中有效地传达这些发现。此外，我相信在完成这些项目后，我将能够成功地竞争一辆R01。最终，这将使我能够通过进行高质量的研究和指导年轻科学家，继续为成瘾研究领域做出贡献。

DESCRIPTION (provided by applicant): Early in my career as a scientist, I decided that communication was the key to all biological processes. This ideology has evolved into a keen interest in the study of synaptic transmission. In the lab of Danny G. Winder, Ph.D. I began my training in synaptic physiology publishing many papers on modulation of excitatory synaptic transmission by metabotropic glutamate receptors and their in vivo recruitment by cocaine. During my postdoctoral training, I have continued to study synaptic transmission in reward related circuitry in the lab of Robert C. Malenka, M.D., Ph.D. Dr. Malenka is a renowned synaptic physiologist and has trained many prominent figures in the synaptic physiology and addiction fields, Antonello Bonci (NIDA), Karl Deisseroth (Stanford), Dan Feldman (UC Berkeley), Pablo Castillo (Albert Einstein), John Isaac (NIH, now Lilly), Anatol Kreitzer (UCSF), Michael Crair (Yale), and Mark Thomas (Univ. Minnesota) to name a few. It is my goal to continue this tradition by obtaining an independent lab in academia studying the role of synaptic transmission in rewarding and aversive behaviors. My area of study differs from Dr. Malenka in that in addition to excitatory transmission, I am also interested in studying inhibitory and neuromodulatory transmission onto NAc interneurons as well as primary output neurons. Eventually, I plan to expand disease models and study effects of aversive states, such as acute and chronic pain, on NAc synaptic circuitry. To do this I am utilizing state of the art techniques and sophisticated yet simple approaches to address these issues in the Nucleus Accumbens (NAc). The ultimate goal of this project is to gain a better understanding of synaptic function in the NAc circuitry and to begin to address how these circuits are recruited to elicit addiction related behaviors. The NAc, as part of the mesolimbic dopamine system, integrates a complex mix of excitatory, inhibitory and modulatory inputs to optimize adaptive motivated behaviors. Dynamic alterations in synaptic transmission within this circuitry are strongly implicated in the development and expression of addictive disorders. The specific aims involve using whole-cell recordings from in vitro slices to define basic properties of NAc neurons and how these are modified by in vivo cocaine exposure. In this proposal, the effects of in vivo cocaine exposure on synaptic properties of NAc output neurons and local microcircuit interneurons (INs) will be delineated utilizing bacterial artificial chromosome (BAC) transgenic marker mice that specifically label direct and indirect pathway medium spiny neurons (MSNs), GABAergic and cholinergic INs. Also, the synaptic properties of three distinct excitatory inputs onto NAc, MSNs and INs will be characterized and the consequences of in vivo cocaine experience on these specific inputs will be determined using virally expressed channel rhodopsin (ChR2). The objectives for the mentored phase of this proposal are: (1) to examine the synaptic properties of direct and indirect MSNs following in vivo cocaine experience, and (2) to determine if specific excitatory synaptic inputs onto these MSNs are differentially altered following in vivo cocaine experience utilizing optogenetic approaches. The independent phase will address: (1) afferent specific basal and drug-induced alterations in excitatory synaptic properties of NAc INs, (2) basal and drug-induced changes in synaptic connectivity between INs and MSNs and (3) behavioral effects of light-induced (ChR2) activation of NAc INs in drug related context, all of which utilize state-of-the-art optogenetic approaches. The results of the proposed experiments will provide a fundamental knowledge of the changes in the synaptic circuitry of the NAc in a pathophysiological state and have implications on future targets for treatment of addiction related behaviors. Additionally, the careful detailed approach of this study provides the foundation for the study of other drugs of abuse and addiction models, as well as additional affirmative disorders associated with maladaptive processes in the NAc. It is my expectation that upon completion of the mentored project I will have the technical and intellectual expertise to successfully run my own independent lab at a respected institute of higher learning. I will have developed tools to effectively communicate these findings at meetings and in publications. Additionally, it is my belief that upon completion of these projects, I will be able to successfully compete for an R01. Ultimately, this will allow me to continue to contribute to the field of addiction research both by producing quality research and mentoring young scientists.