NEURONAL NITRIC OXIDE SYNTHASE IN NEUROPATHIC PAIN

这项提议的长期目标是了解由周围神经损伤（神经性疼痛）引起的疼痛综合征的分子机制。这些疼痛状态代表了影响牙齿和口腔面部疾病患者日常生活质量的主要问题。这些疾病通常对常规镇痛药无效。不幸的是，人们对神经性疼痛的分子机制知之甚少，因此，没有专门针对神经性疼痛的有效药物治疗。我们的初步数据表明，在大鼠周围神经损伤模型中，神经元一氧化氮合酶（nNOS）的感觉神经元mRNA水平升高与神经性疼痛（异常性疼痛）的发展之间存在相关性。这表明，神经元来源的NO可能在神经性疼痛的加工和/或调节中充当第二信使，而在转录或mRNA加工水平上对nNOS表达的调节可能强调了周围神经损伤后神经元的可塑性。本课题拟利用大鼠神经性疼痛模型的背根神经节（DRG）和脊髓组织，进一步研究nNOS表达在神经性疼痛发生发展中的机制和功能作用。分子，免疫组织化学和药理学技术将被利用。本建议的具体目的是：。1)通过比较未发生异位性疼痛的大鼠品系与易发生异位性疼痛的大鼠品系的nNOS mRNA和蛋白水平，探讨神经性疼痛的发生与nNOS表达之间可能的遗传联系。2)通过研究轴浆转运、反馈抑制和神经放电在nNOS调控和神经性疼痛发生中的作用，探讨nNOS调控的细胞机制及其与神经性疼痛发生的关系。3)观察异位性疼痛发生过程中nNOS蛋白表达与mRNA水平的相关性，探讨神经性疼痛大鼠DRG和脊髓中nNOS的细胞定位。

The long term objective of this proposal is to understand the molecular mechanism of pain syndromes resulting from peripheral nerve injury (neuropathic pain). These pain states represent major problems affecting the quality of daily life of patients with dental and orofacial disorders. These disorders do not typically respond to conventional analgesics. Unfortunately, the molecular mechanisms of neuropathic pain are poorly understood and, as a consequence, there are no specifically targeted, effective pharmacological agents available for neuropathic pain treatment. Our preliminary data indicate a correlation between increased mRNA levels in sensory neurons of neuronal nitric oxide synthase (nNOS), an enzyme that catalyzes the production of nitric oxide (NO), and the development of neuropathic pain (allodynia) in a rat model of peripheral nerve injury. This suggests that neuronal-derived NO may serve as a second messenger in the processing and/or modulation of neuropathic pain and regulation of nNOS expression at the level of transcription or mRNA processing may underline the neuronal plasticity following peripheral nerve injury. This research proposal is designed to further study the mechanism and functional role of nNOS expression to the development of neuropathic pain using tissues of dorsal root ganglia (DRG) and spinal cord from a rat neuropathic pain model. Molecular, immunohistochemical and pharmacological techniques will be utilized. The specific aims of this proposal are:. 1) To examine a possible genetic linkage between development of neuropathic pain and expression of nNOS by comparing the nNOS mRNA and protein levels in a rat strain that does not develop allodynia with those in a rat strain susceptible to allodynia development. 2) To examine the cellular mechanism of nNOS regulation and its relation to the development of neuropathic pain by examining contributions of axoplasmic transport, feedback inhibition and nerve discharge on the regulation of nNOS and neuropathic pain development. 3) To correlate expression of nNOS protein with its mRNA levels at intervals during the development of allodynia and to examine the cellular localization of nNOS in DRG and spinal cord of rats with neuropathic pain.