Neurotransmitter control of substance P release in the spinal cord

神经递质控制脊髓中 P 物质的释放

• 批准号: 8838137
• 负责人: Juan Carlos Garcia Marvizon
• 金额: --
• 依托单位: VA GREATER LOS ANGELES HEALTHCARE SYSTEM
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-01 至 2015-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8838137
• 关键词: Adrenergic Agents; Adrenergic Agonists; Adrenergic Receptor; Affect; Aging; Agonist; Analgesics; Binding; Brain; Calcium Channel; Cell Culture Techniques; Data; Diabetes Mellitus; Esthesia; Exposure to; GTP-Binding Proteins; General Population; Goals; Hyperalgesia; In Situ; Incidence; Lead; Lesion; Measures; Mediating; Modeling; Molecular; Morphine; Nerve; Nervous system structure; Neuraxis; Neurons; Neuropathy; Neurotransmitters; Nociception; Opiates; Opioid; Opioid Receptor; Pain; Patients; Perception; Pharmaceutical Preparations; Phosphorylation; Population; Posterior Horn Cells; Rattus; Signal Pathway; Signal Transduction; Site; Small Interfering RNA; Spinal Cord; Substance P; Substance P Receptor; Synapses; System; United States; Veterans; adrenergic; allodynia; chronic pain; combat; neurotransmitter release; pain inhibition; painful neuropathy; receptor; receptor internalization; spontaneous pain; src-Family Kinases; voltage

DESCRIPTION (provided by applicant): Neuropathic pain refers to alterations in pain perception (spontaneous pain, hyperalgesia and allodynia) that arise from lesions in the nervous system. It affects a large sector of the population. Veterans are especially susceptible to neuropathic pain, because of their exposure to combat wounds and diabetes. Neuropathic pain is notoriously difficult to treat. It responds poorly to opiates, probably because of a loss of their analgesic effect in the spinal cord. A key site of pain modulation is the synapses between nociceptive afferents and dorsal horn neurons. In particular, substance P-containing afferents that make direct synapses with dorsal horn neurons that project to the brain. The receptor for substance P, the neurokinin 1 receptor, is present in these neurons and produces an increase in their excitability responsible for hyperalgesia. Moreover, since there is a single synapse between the substance P-containing afferents and the brain, changes in transmitter release in this synapse have important effects on pain. This project will measure substance P release as an indicator of overall activity of these synapses, investigating how it is inhibited by two receptors present in primary afferent terminals: the 5-opioid receptor and the 12 adrenergic receptor. Recent studies in cell cultures and our data indicate that 5-opioid receptors inhibit neurotransmitter release by a mechanism unique of primary afferents: phosphorylation of voltage-gated calcium channels by Src family kinases. In contrast, 12 receptors inhibit these calcium channels by the mechanism commonly found in other neurons: binding of G protein 23 subunits (G23). Preliminary data also show that substance P release is inhibited by 5-opioid receptors in normal rats but not in neuropathic rats, which parallels the lack of efficacy of opioids in neuropathic pain. In contrast, 12 receptor agonists do not lose their efficacy in neuropathic pain. We formulated the following hypotheses: 1) 5-opioid and 12 adrenergic receptors inhibit SP release by inactivating Ca(V) channels; the effect of 12 receptors is mediated by G23 while that of 5-opioid receptors is additionally mediated by SFKs; 2) in neuropathic pain, inhibition of SP release by 5-opioid receptors is loss, but its inhibition by 12 adrenergic receptors and synergy between 5- opioid and 12 receptors are still present. The Specific Aims of this project are: 1) to study the mechanisms by which 5-opioid and 12 receptors inhibit substance P release; 2) to study changes in opioid and adrenergic inhibition of substance P release in neuropathic pain. The project is significant in that it will study unique signaling mechanisms in nociceptive afferents that can become prime targets for developing analgesic drugs. Moreover, it will investigate how these signaling mechanisms undergo specific changes in neuropathic pain. The methodological approach in Aim 1 will consist in using neurokinin 1 receptor internalization as an in situ measure of substance P release, and pharmacological and molecular (small interfering RNA) approaches to dissect the signaling pathways used by the 5-opioid and 12 receptors. In Aim 2, we will use a rat model of neuropathic pain to investigate alterations in these receptors and their signaling systems.

描述（由申请人提供）： 神经性疼痛是指由神经系统病变引起的疼痛感知的改变（自发性疼痛、痛觉过敏和异常性疼痛）。它影响到很大一部分人口。退伍军人特别容易受到神经性疼痛的影响，因为他们经常遭受战伤和糖尿病。众所周知，神经性疼痛很难治疗。它对阿片类药物的反应很差，可能是因为它们在脊髓中失去了镇痛作用。疼痛调节的关键位点是伤害性传入神经元和背角神经元之间的突触。特别是，含有 P 物质的传入神经与投射到大脑的背角神经元形成直接突触。 P 物质的受体，即神经激肽 1 受体，存在于这些神经元中，并导致其兴奋性增加，从而导致痛觉过敏。此外，由于含P物质的传入神经和大脑之间存在单个突触，因此该突触中递质释放的变化对疼痛具有重要影响。该项目将测量 P 物质的释放，作为这些突触总体活动的指标，研究其如何被初级传入末梢中存在的两种受体（5-阿片受体和 12 肾上腺素受体）抑制。最近的细胞培养研究和我们的数据表明，5-阿片受体通过初级传入的独特机制抑制神经递质释放：Src 家族激酶对电压门控钙通道的磷酸化。相反，12 受体通过其他神经元中常见的机制抑制这些钙通道：结合 G 蛋白 23 亚基 (G23)。初步数据还表明，在正常大鼠中，P 物质的释放受到 5-阿片受体的抑制，但在神经病理性大鼠中则不然，这与阿片类药物在神经病理性疼痛中缺乏疗效相似。相比之下，12受体激动剂并没有失去治疗神经性疼痛的功效。我们提出以下假设：1）5-阿片类药物和12肾上腺素能受体通过失活Ca(V)通道来抑制SP释放； 12种受体的作用由G23介导，而5-阿片受体的作用另外由SFK介导； 2)在神经性疼痛中，5-阿片受体对SP释放的抑制作用丧失，但其对12种肾上腺素能受体的抑制作用以及5-阿片受体与12种受体之间的协同作用仍然存在。该项目的具体目标是： 1）研究5-阿片受体和12受体抑制P物质释放的机制； 2) 研究神经性疼痛中阿片类药物和肾上腺素能抑制 P 物质释放的变化。该项目的意义重大，因为它将研究伤害性传入的独特信号机制，这些机制可以成为开发镇痛药物的主要目标。此外，它将研究这些信号机制如何在神经性疼痛中经历特定的变化。目标 1 的方法学方法将包括使用神经激肽 1 受体内化作为 P 物质释放的原位测量，以及药理学和分子（小干扰 RNA）方法来剖析 5-阿片类药物和 12 受体使用的信号传导途径。在目标 2 中，我们将使用神经性疼痛大鼠模型来研究这些受体及其信号系统的变化。