Adaptations following chronic opioid treatment and withdrawal

项目概要 吗啡和芬太尼等阿片类药物可有效缓解急性和术后疼痛，但长期效果不佳 由于其滥用倾向，使用存在问题。长期使用阿片类药物会导致细胞和电路水平的适应 这可能会导致成瘾，但确切的机制尚不完全清楚。此外，退出 阿片类药物揭示了这些适应性变化，促进药物摄入量增加并促进复发。这个 该提案将使用光遗传学方法将谷氨酸投射与阿片类药物敏感（丘脑）分离 以及进入小鼠纹状体的不敏感（皮质）末端。全细胞电生理记录 脑切片将用于研究慢性阿片类药物后介导适应性变化的机制 治疗和停药。 受体磷酸化是介导急性脱敏和长期作用的关键细胞事件 细胞体特异性μ阿片受体（MOR）的耐受性，但对磷酸化的作用知之甚少 介导突触前末端 MOR 的信号传导。因此，目标 1 中的实验将阐明 磷酸化介导对吗啡和芬太尼的急性敏感性和长期耐受性 终末期 MOR 的长期治疗。此外，长期治疗后的适应超出了 受体水平，并可以影响下游第二信使，如腺苷酸环化酶。腺苷酸环化酶可以 在中枢神经系统突触中代谢为腺苷以调节谷氨酸释放。实验 因此，目标 2 将重点关注纹状体中腺苷释放和调节的机制。 突触，特别是长期阿片类药物治疗后 MOR 在介导腺苷浓度中的作用。 总体假设是 MOR 磷酸化是一个关键的信号传导事件，它建立了急性 对阿片类药物的敏感性和长期耐受性，MOR 的激活在介导阿片类药物的敏感性和长期耐受性方面发挥着关键作用 纹状体突触中腺苷的浓度。 最终，这项研究的结果将解决磷酸化在末端 MOR 信号传导中的作用 并确定长期阿片类药物治疗和戒断导致的受体和细胞适应。由 观察吗啡（部分激动剂）和芬太尼（完全激动剂）的作用，综合 了解慢性阿片类药物暴露后受体磷酸化对突触传递的作用 将成立。了解介导突触活动的关键受体和细胞变化 慢性阿片类药物治疗是确定治疗阿片类药物使用的新治疗靶点的关键第一步 紊乱。

Project Summary Opioids such as morphine and fentanyl effectively relieve acute and post-operative pain but long-term use is problematic due to their abuse liability. Long-term opioid use causes cellular and circuit level adaptations that can lead to addiction, but the precise mechanisms are not fully understood. Furthermore, withdrawal from opioids unmasks these adaptive changes facilitating increased drug intake and promoting relapse. This proposal will use an optogenetic approach to isolate glutamate projection from both opioid sensitive (thalamic) and insensitive (cortical) terminals coming into the striatum in mice. Whole-cell electrophysiological recordings in brain slices will be used to investigate the mechanisms mediating adaptive changes following chronic opioid treatment and withdrawal. Receptor phosphorylation is a key cellular event mediating acute desensitization and long-term tolerance in cell-body specific µ-opioid receptors (MORs), but little is known about the role of phosphorylation in mediating signaling in presynaptic terminal MORs. Experiments in Aim 1 will therefore elucidate the role of phosphorylation in mediating acute sensitivity and long-term tolerance to both morphine and fentanyl after chronic treatment in terminal MORs. Furthermore, adaptations following chronic treatment go beyond the receptor level and can influence downstream second messengers like adenylyl cyclase. Adenylyl cyclase can be metabolized to adenosine in central nervous system synapses to modulate glutamate release. Experiments in Aim 2 will therefore focus on the mechanisms underlying release and regulation of adenosine in striatal synapses, specifically the role of MORs in mediating adenosine concentration after chronic opioid treatment. The overall hypothesis is that MOR phosphorylation is a key signaling event that establishes both acute sensitivity and long-term tolerance to opioids, and activation of MORs plays a critical role in mediating the concentration of adenosine in striatal synapses. Ultimately, the results from this study will address the role of phosphorylation in terminal MOR signaling and determine receptor and cellular adaptations that result from chronic opioid treatment and withdrawal. By looking at the effects of both morphine (a partial agonist) and fentanyl (a full agonist), a comprehensive understanding of the role of receptor phosphorylation on synaptic transmission after chronic opioid exposure will be established. Understanding the key receptor and cellular changes that mediate synaptic activity after chronic opioid treatment is a crucial first step in identifying novel therapeutic targets to treat opioid use disorder.