Modulation of protracted opioid withdrawal by dorsal raphe dynorphin neurons

项目摘要 阿片类药物使用障碍（OUD）是一种慢性复发性疾病，2017年美国的损失超过1万亿美元 一个人虽然最初是由大脑奖励回路驱动的，但阿片类药物的消费越来越多地涉及与压力相关的 导致不适应情绪状态的神经回路在禁欲的几周、几个月和几年里， 阿片类药物使用，复发的风险增加了情绪症状，如社交回避，抑郁症， 对阿片类药物的渴望同样，在长期阿片类药物戒断期间自我孤立的倾向增加了 过量致死的风险美国阿片类药物过量的迅速升级反映了对更多数据的需求。 阿片类药物长期戒断的神经机制神经肽强啡肽和κ阿片样物质 受体（KOR）有助于压力、厌恶和戒断的行为后果。虽然有证据 提示KOR效应可能是由于调节多巴胺和5-羟色胺在核中的释放 在阿片类药物戒断过程中，调节KOR控制的脑区和神经机制仍然存在。 知识上的巨大差距在K99/R 00获得独立奖的途径中，我的目标是通过以下方式确定机制： 哪些KOR介导了戒断过程中的行为变化。使用一种慢性非偶然的 吗啡暴露，我已经收集了初步的数据表明：1）KOR活性在NAc控制社会 回避和快感缺乏产生于长期戒断和2）人口的强啡肽生产 中缝背核中的神经元，而不是NAc本身中的强啡肽神经元，介导相同的效应。 在指导阶段，在目标1，我将学习执行体内光遗传学程序和纤维光度测定 记录以表征中缝背核强啡肽神经元投射到NAc在戒断中的作用 行为。在目标2中，我将扩展非偶然注入模型，并建立一个新的非偶然注入模型。 瑞芬太尼自我给药，并检查长期戒断期间的复发行为。我还将测试 自我管理后社会和抑郁样行为的变化。在独立阶段，在目标3中， 我将利用我在K99阶段的训练，将联合收割机光遗传学和中缝背核的纤维光度学记录结合起来 强啡肽输入NAc与瑞芬太尼自我给药和复发测试。在目标4中，我将扩展 用非偶然注射收集的额外初步数据显示， 多巴胺神经元分别对社交回避和抑郁样行为至关重要。我会用纤维 多巴胺和5-羟色胺的光度测定和荧光传感器记录在NAc中的释放 戒断测试此外，我将研究多巴胺和血清素的动态在自我管理模式 通过测试具有相同细胞类型特异性KOR敲除的小鼠并进行光度测定， 在NAC中的释放记录。总的来说，这项建议将调查长期存在的关键机制， 阿片类药物戒断与先进的技术相结合，同时为我提供工具， 建立一个独立的研究计划，旨在解剖OUD的发病机制所必需的。

Project summary Opioid use disorder (OUD) is a chronic relapsing disorder that has cost the U.S. more than $1 trillion in 2017 alone. While initially driven by brain reward circuits, opioid consumption increasingly engages stress-related neural circuits that drive maladaptive emotional states. During the abstinent weeks, months, and years following opioid use, the risk of relapse is increased by emotional symptoms, such as social avoidance, depression, and opioid cravings. Similarly, tendencies to self-isolate during periods of protracted opioid withdrawal increase the risk of lethal overdose. The rapid escalation of opioid overdoses in the U.S. reflects the need for more data on neural mechanisms underlying protracted opioid withdrawal. The neuropeptide dynorphin and kappa opioid receptors (KOR) contribute to stress, aversion, and behavioral consequences of withdrawal. While evidence suggests that KOR effects may be due to modulation of dopamine and serotonin release in the nucleus accumbens (NAc), the brain regions and neural mechanisms mediating KOR control of opioid withdrawal remain a critical gap in knowledge. In this K99/R00 pathway to independence award, I aim to identify mechanisms by which KORs mediate changes in behavior during withdrawal. Using a mouse model of chronic, non-contingent morphine exposure, I have collected preliminary data indicating that 1) KOR activity in the NAc controls social avoidance and anhedonia produced during protracted withdrawal and 2) a population of dynorphin-producing neurons in the dorsal raphe nucleus, but not dynorphin neurons in the NAc itself, mediate the same effects. During the mentored phase, in Aim 1, I will learn to perform in vivo optogenetic procedures and fiber photometry recordings to characterize the role of dorsal raphe dynorphin neuron projections to the NAc in withdrawal behaviors. In Aim 2, I will expand on the model of non-contingent injections and establish a new model of remifentanil self-administration and examine relapse behavior during protracted withdrawal. I will also test changes in social and depression-like behaviors after self-administration. In the independent phase, in Aim 3, I will use my training from the K99 phase to combine optogenetics and fiber photometry recordings of dorsal raphe dynorphin inputs to the NAc with remifentanil self-administration and relapse testing. In Aim 4, I will expand on additional preliminary data collected with non-contingent injections showing that KOR expression in serotonin and dopamine neurons is critical for social avoidance and depression-like behaviors, respectively. I will use fiber photometry and fluorescent sensors of dopamine and serotonin to record release in the NAc during protracted withdrawal testing. In addition, I will examine dopamine and serotonin dynamics in the self-administration model developed in Aim 2 by testing mice with the same cell-type specific KOR knockouts and performing photometry recordings of release in the NAc. Overall, this proposal will investigate key mechanisms underlying protracted opioid withdrawal with a combination of advanced techniques, while simultaneously providing me with the tools necessary for establishing an independent research program aimed at dissecting the pathogenesis of OUD.