Signaling Mechanisms of Opioid-Induced Hyperalgesia and Tolerance

项目摘要 阿片类止痛药是治疗癌症以及组织和神经损伤引起的严重疼痛的主要药物。 然而，临床使用μ阿片受体激动剂可导致痛觉过敏和止痛效果丧失， 这导致阿片类药物剂量上升，并仍然是使用阿片类药物充分缓解疼痛的主要障碍。虽然 一些证据表明，痛觉过敏和阿片类药物诱导的止痛耐受之间存在强烈的联系， 对于这两个重要现象的统一细胞和分子机制还知之甚少。少校 本研究的目的是确定阿片类药物诱导的基本信号机制。 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 刺激突触前N-甲基-D-天冬氨酸受体表达TRPV1的初级传入 (NMDARs)，这是OHT的关键机制。NMDAR是治疗OHT的临床验证靶点， 但关于阿片类药物是如何导致脊髓水平突触前NMDAR活性增加的知之甚少。另外， 加巴喷丁类化合物可以通过一种基本未知的机制在动物模型和患者中降低OHT。我们的 初步数据显示，磷脂酶C在脊髓NMDAR活性增加和在 啊哈。此外，阿片诱导的磷脂酶C刺激促进了α-2和δ-1之间的相互作用 NMDARs，这种相互作用被加巴喷丁减弱。在这个项目中，我们将检验我们的中心假设 磷脂酶C-β依赖的信号转导途径主要通过促进 α-2、δ-1-NMDAR相互作用增加脊髓水平突触前NMDAR活性及加巴喷丁 通过阻断α-2、δ-1-NMDAR的相互作用，降低OHT和脊髓突触前NMDAR的活性。我们将使用 多学科方法，包括蛋白质生物化学，脊髓切片的电生理记录， 小干扰RNA基因敲除，以及遗传α2δ-1和磷脂酶C-β亚型基因敲除小鼠。建议进行的研究包括 非常有意义，因为它将极大地促进我们对基本信号机制的理解 参与了OHT。我们的发现也有助于开发针对PLC-β同工酶和 α-2，δ-1-NMDAR相互作用位点，用于治疗特发性高血压，减少阿片类药物的消耗和依赖。

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.