Signaling Mechanisms of Opioid-Induced Hyperalgesia and Tolerance

项目摘要 阿片类镇痛药是治疗癌症和组织及神经损伤引起的严重疼痛的主要药物。 然而，μ-阿片受体激动剂的临床使用可引起痛觉过敏和镇痛功效的丧失， 这导致阿片样物质剂量增加，并且仍然是阿片样物质充分缓解疼痛的主要障碍。虽然 一些证据表明，阿片类药物诱导的痛觉过敏和镇痛耐受之间有很强的联系， 对于这两种重要现象的统一的细胞和分子机制知之甚少。主要 本提案的目的是确定负责阿片类药物诱导的 痛觉过敏和耐受（OHT）。阿片类药物给药可导致谷氨酸释放持续增加， 通过刺激突触前N-甲基-D-天冬氨酸受体表达TRPV1的初级传入神经 （NMDAR），其代表OHT的关键机制。NMDAR是治疗OHT的临床验证靶点， 但关于阿片类药物如何导致脊髓水平突触前NMDAR活性增加的知之甚少。还有， 加巴喷丁类化合物可以通过一种很大程度上未知的机制减少动物模型和患者中的OHT。我们 初步数据显示，磷脂酶C与脊髓NMDAR活性的增加和脊髓神经元的损伤密切相关。 好的。此外，阿片诱导的磷脂酶C刺激促进了α 2 δ-1和α 2 δ-1之间的相互作用。 NMDARs，加巴喷丁减弱了这种相互作用。在这个项目中，我们将测试我们的中心假设 磷脂酶C-β依赖性信号传导主要通过促进OHT的发生， α 2 δ-1-NMDAR相互作用增加脊髓水平突触前NMDAR活性，加巴喷丁 通过中断α 2 δ-1-NMDAR相互作用降低OHT和脊髓突触前NMDAR活性。我们将使用一个 多学科方法，包括蛋白质生物化学，脊髓切片电生理记录， siRNA敲除和遗传α 2 δ-1和磷脂酶C-β同种型敲除小鼠。拟议的研究是 这是非常重要的，因为它将极大地促进我们对基本信号机制的理解 参与OHT。我们的发现也有助于开发针对PLC-β同工酶的新治疗药物， α 2 δ-1-NMDAR相互作用位点用于治疗OHT并减少患者的阿片类药物消耗和依赖。

Project Summary Opioid analgesics are the mainstay of treatment for severe pain caused by cancer and by tissue and nerve injury. However, clinical use of μ-opioid receptor agonists can cause hyperalgesia and the loss of analgesic efficacy, which lead to opioid dose escalation and remain the major obstacles to adequate pain relief with opioids. Although some evidence suggests a strong link between hyperalgesia and analgesic tolerance induced by opioids, the unifying cellular and molecular mechanisms for these two important phenomena are poorly understood. The major objective in this proposal is to identify the essential signaling mechanisms responsible for opioid-induced hyperalgesia and tolerance (OHT). Opioid administration can cause a persistent increase in glutamate release from TRPV1-expressing primary afferents through stimulation of presynaptic N-methyl-D-aspartate receptors (NMDARs), which represents a key mechanism for OHT. NMDARs are a clinically validated target for treating OHT, but little is known about how opioids lead to increased presynaptic NMDAR activity at the spinal cord level. Also, gabapentinoids can reduce OHT in animal models and in patients through a largely unknown mechanism. Our preliminary data showed that phospholipase C was critically involved in increased spinal NMDAR activity and in OHT. Furthermore, opioid-induced phospholipase C stimulation promoted the interaction between α2δ-1 and NMDARs, and such an interaction was diminished by gabapentin. In this project, we will test our central hypothesis that phospholipase C-β–dependent signaling contributes to the development of OHT predominantly by promoting α2δ-1–NMDAR interaction to increase presynaptic NMDAR activity at the spinal cord level and that gabapentin reduces OHT and spinal presynaptic NMDAR activity by interrupting α2δ-1–NMDAR interaction. We will use a multidisciplinary approach, including protein biochemistry, electrophysiological recordings in spinal cord slices, siRNA knockdown, and genetic α2δ-1 and phospholipase C-β isoform knockout mice. The proposed studies are highly significant because it will greatly advance our understanding of the fundamental signaling mechanism involved in OHT. Our findings could also help developing new therapeutic agents targeting PLC-β isozymes and α2δ-1–NMDAR interaction sites for treating OHT and reducing opioid consumption and dependence in patients.