NEURONAL NITRIC OXIDE SYNTHASE IN NEUROPATHIC PAIN

这项建议的长期目标是了解周围神经损伤(神经病理性疼痛)引起的疼痛综合征的分子机制。这些疼痛状态是影响牙科和口腔疾病患者日常生活质量的主要问题。这些疾病通常对传统的止痛药没有反应。不幸的是，神经病理性疼痛的分子机制还知之甚少，因此，目前还没有专门针对神经病理性疼痛的有效的药物治疗。我们的初步数据表明，在周围神经损伤的大鼠模型中，神经元型一氧化氮合酶(NNOS)(一种催化一氧化氮(NO)产生的酶)的mRNA水平升高与神经病理性疼痛(痛觉异常)的发生之间存在相关性。提示神经源性NO可能在神经病理性疼痛的处理和/或调节中起第二信使的作用，在转录或mRNA处理水平上对nNOS表达的调节可能突出了周围神经损伤后神经元的可塑性。本研究拟通过建立大鼠神经病理性疼痛模型，利用背根神经节(DRG)和脊髓组织进一步研究nNOS表达在神经病理性疼痛发生发展中的机制和功能作用。将利用分子、免疫组织化学和药理学技术。这项建议的具体目标是：。1)通过比较不发生痛觉异常的大鼠品系和易发生痛觉异常的品系大鼠的nNOS mRNA和蛋白水平，研究神经病理性疼痛的发生与nNOS表达之间可能的遗传联系。2)通过检测轴浆转运、反馈抑制和神经放电在nNOS调控和神经病理性疼痛发生中的作用，探讨nNOS调控的细胞机制及其与神经病理性疼痛发生的关系。3)探讨神经病理性疼痛大鼠背根神经节和脊髓中nNOS蛋白表达与其mRNA表达的相关性，以及神经病理性疼痛大鼠背根神经节和脊髓中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.