Adaptations following chronic opioid treatment and withdrawal

项目摘要 阿片类药物如吗啡和芬太尼有效缓解急性和手术后疼痛，但长期 由于他们的滥用责任，使用是有问题的。长期使用阿片类药物会导致细胞和电路水平的适应 这可能会导致上瘾，但确切的机制尚不完全清楚。此外，退出 阿片类药物揭开了这些适应性变化的面纱，促进了药物摄入量的增加和复发。这 提案将使用光遗传学方法将谷氨酸投射从阿片类药物敏感(丘脑)中分离出来 以及小鼠纹状体的不敏感(皮质)终末。全细胞电生理记录 将用于研究慢性阿片类药物后适应性变化的调节机制 治疗和戒断。 受体磷酸化是介导急性脱敏和长期脱敏的关键细胞事件 细胞体特异性阿片受体(MORS)的耐受，但对磷酸化的作用知之甚少 参与了突触前终末MORS的信号传递。因此，目标1中的实验将阐明 磷酸化在介导吗啡和芬太尼急性敏感性和长期耐受性中的作用 晚期MORS的慢性治疗。此外，慢性治疗后的适应能力超出了 受体水平，并可影响下游的第二信使，如腺苷环化酶。腺酰环化酶可以 在中枢神经系统突触中被代谢成腺苷，以调节谷氨酸的释放。实验 因此，目标2将集中于纹状体腺苷释放和调节的潜在机制 突触，特别是MORS在慢性阿片类药物治疗后调节腺苷浓度中的作用。 总体假设是，MOR磷酸化是一个关键的信号事件，它建立了急性 对阿片类药物的敏感性和长期耐受性，以及MORS的激活在介导 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终末MOR信号转导中的作用 并确定慢性阿片类药物治疗和戒断导致的受体和细胞适应。通过 看看吗啡(部分激动剂)和芬太尼(完全激动剂)的效果，一个全面的 慢性阿片类药物暴露后受体磷酸化在突触传递中的作用 将会建立起来。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。 无序。

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.