Regulation of neuronal activity in the paraventricular thalamus by chronic morphine

项目摘要 阿片类药物滥用和过量死亡的高比率是美国的一个重大公共卫生问题 各州。避免戒断症状是阿片类药物持续使用和过量的主要驱动因素。 了解慢性阿片类药物暴露诱导的神经适应对 新的有效疗法的鉴定。丘脑室旁核(PVT)位于 丘脑背侧中线，编码与药物成瘾相关的行为状态，包括唤醒，饥饿， 追求回报和厌恶。最近的研究已经指出了PVT及其投射在 调节阿片类药物的许多行为效应。Mu-阿片受体(MOR)在许多大脑中表达 这些区域共同调节阿片类药物的许多细胞和行为影响。目前还不清楚是什么原因 下丘脑室旁核内MOR对吗啡戒断后躯体体征的影响。此外，还有几个 人们对一些重要问题仍知之甚少。如何在PVT中激活MOR？慢性病是如何 吗啡暴露和随后的戒断影响PVT的动作电位放电--最终输出 神经元？神经元活动的改变在多大程度上促进了吗啡戒断 躯体体征？为了解决这些问题，我们提出了两个具体目标。在Aim I中，我将确定 MOR的激活和脱敏改变PVT神经元输出的程度 吗啡戒断。将使用切片电生理和体内钙离子成像与纤维光度法 来解决这个问题。在AIM II中，我将使用CRE-loxP技术选择性地删除PVT中的MOR和 研究其对戒断诱导的躯体体征的影响。此外，我将测试是否阻止取款- PVT神经元兴奋性的增加影响吗啡戒断的厌恶行为效应。 这一项目的完成有望提供极好的培训机会，学习广泛的 强大的技术，包括体外切片电生理学，体内纤维光度学，原位杂交， 免疫组织化学、病毒微量注射、药理学和动物行为分析。此外，建议的 研究将加深我们对阿片类药物不良反应潜在的细胞和电路机制的理解 戒烟。

Project Summary High rates of opioid abuse and overdose deaths represent a substantial public health issue in the United States. Avoidance of withdrawal symptoms is a primary driver of continued opioid use and overdose. Understanding the neuroadaptations induced by chronic opioid exposure holds great promise for the identification of novel and efficacious therapeutics. The paraventricular thalamic nucleus (PVT), located in the dorsal midline thalamus, encodes behavioral states relevant to drug addiction, including arousal, hunger, reward-seeking, and aversion. Recent studies have pointed a critical role of the PVT and its projections in regulating many behavioral effects of opioids. The Mu-opioid receptor (MOR) is expressed in many brain regions, which collectively mediate many cellular and behavioral effects of opioids. It remains unknown to what extent the MOR in the PVT contributes to morphine withdrawal-induced somatic signs. In addition, several important questions remain poorly understood. How is the MOR is activated in the PVT? How does chronic morphine exposure and subsequent withdrawal affect the action potential firing—the final output—of PVT neurons? To what extent do the changes in neuronal activity contribute to morphine withdrawal-induced somatic signs? Two Specific Aims are proposed to address these questions. In Aim I, I will determine the extent to which activation and desensitization of the MOR alters neuronal output of PVT neurons following morphine withdrawal. Slice electrophysiology and in vivo Ca2+ imaging with fiber photometry will be employed to address this question. In Aim II, I will use Cre-LoxP technique to selectively delete the MOR in the PVT and examine its impact on withdrawal-induced somatic signs. Additionally, I will test whether blocking withdrawal- induced increase in excitability in PVT neurons affects the aversive behavioral effects of morphine withdrawal. Completion of this project is expected to provide excellent training opportunities to learn a wide range of powerful techniques, including ex vivo slice electrophysiology, in vivo fiber photometry, in situ hybridization, immunohistochemistry, viral microinjection, pharmacology, and animal behavior assays. Further, the proposed research will deepen our understanding of cellular and circuit mechanisms underlying adverse effects of opioid withdrawal.