Peripheral mechanisms of central neuropathic pain in multiple sclerosis

阮凯拉 项目摘要/摘要 神经病理性疼痛(NP)困扰着超过50%的多发性硬化症(MS)患者，但目前的疼痛治疗方法 缓解是不够的，部分原因是驱动多发性硬化症疼痛的机制尚不清楚。在一种广泛使用的 多发性硬化症动物模型、实验性自身免疫性脑脊髓炎(EAE)、电生理研究进展 背根神经节(DRG)初级传入神经元(PAN)的研究结果显示：1)中枢神经的兴奋性增强； 2)小直径神经纤维后超极化增加。这些数据 为我的长期目标提供了前提，即研究PAN中驱动NP的敏化机制 EAE模型。通过行为、转基因和消融技术，我建议评估A 和C纤维到MS Pain，在检验EAE产生持续的过度兴奋的总体假设 与背角神经元活动增加有关的A和/或C-伤害性感受器(目标1，2)(目标3) 然后，这就驱动了NP。目标1使用神经元消融策略来确定初级传入的哪些亚群 神经元参与了EAE中的NP。我将使用简单的传统神经元消融策略(新生辣椒素， 鞘内辣椒素、鞘内IB4-皂苷、足底鞭毛素/QX-314)，随后是更劳动密集型的 但强大的条件淘汰法消除了日益精确的PAN子集的活性。我预测 建议的干预措施将减少EAE引起的疼痛的关键指标：机械性和寒冷性 过敏(反射性疼痛)和条件性位置厌恶(情感性疼痛)。目标2使用化学遗传学和 光遗传学来验证这一假说，即在EAE中表达MRGPrd或TrkC的PAN是NP所必需的。 我预测，Creer选择性操作抑制IB4神经元的MRgprD+亚群或TrkC+ 有髓神经元的子集(根据目标1a-b的结果做出决定)将减少机械性和冷冻性EAE 过敏症。目标3将验证EAE敏化躯体感觉刺激诱导的假设 脊髓中间神经元和投射神经元的激活。我们的实验室报告说，EAE增加了活性 通过PERK的表达来测量背角神经元的数量。我建议将这些研究扩展到更多 使用脊髓切片Fura-2钙成像对神经元活动进行强有力的测量，并通过评估 不仅是中间神经元的活动，还有投射神经元的活动。匹兹堡疼痛研究中心将 提供指导、支持和学习机会，以促进我的科学和 调查职业抱负。

Nguyen, Kayla PROJECT SUMMARY/ABSTRACT Neuropathic Pain (NP) afflicts over 50% of patients with multiple sclerosis (MS), yet current treatments for pain relief are inadequate, in part because mechanisms that drive MS pain are poorly understood. In a widely-used animal model of MS, experimental autoimmune encephalomyelitis (EAE), recent electrophysiological recordings of primary afferent neurons (PANs) in the dorsal root ganglion (DRG) revealed: 1) hyperexcitability of medium- to-large diameter neurons and 2) an increase in afterhyperpolarization of small-diameter fibers. These data provide the premise for my long-term goal to investigate the sensitization mechanisms at PANs that drive NP in the EAE model. With behavioral, transgenic, and ablation techniques, I propose to assess the contribution of A and C-fibers to MS pain upon testing the overall hypothesis that EAE produces a persistent hyperexcitability of A and/or C-nociceptors (Aim 1,2) that is associated with increased activity of dorsal horn (DH) neurons (Aim 3) that then drives NP. Aim 1 uses neuronal ablation strategies to identify which subpopulations of primary afferent neurons contribute to NP in EAE. I will use simple conventional neuronal ablation strategies (neonatal capsaicin, intrathecal capsaicin, intrathecal IB4-saporin, intraplantar flagellin/QX-314), followed by a more labor-intensive but powerful conditional knockout approach to eliminate the activity of increasingly precise PAN subsets. I predict that the proposed interventions will reduce key indicators of EAE-induced pain: mechanical and cold hypersensitivity (reflexive pain) and conditioned place aversion (affective pain). Aim 2 uses chemogenetics and optogenetics to test the hypothesis that either Mrgprd- or TrkC-expressing PANs are necessary for NP in EAE. I predict that CreER selective manipulations to inhibit either the MrgprD+ subset of IB4 neurons or the TrkC+ subset of myelinated neurons (decision driven by the results of Aim 1a-b) will reduce EAE mechanical and cold hypersensitivity. Aim 3 will test the hypothesis that EAE sensitizes the somatosensory stimulus-induced activation of spinal interneurons and projection neurons. Our laboratory reported that EAE increases the activity of dorsal horn neurons as measured by the expression of pERK. I propose to extend these studies with a more powerful measure of neuronal activity using spinal cord slice Fura-2 calcium imaging, and by assessing the activity not only of interneurons, but also of projection neurons. The Pittsburgh Center for Pain Research will provide guidance, support, and learning opportunities that will promote the development of my scientific and investigative career aspirations.