Neural and Chemical Basis of Pathological Pain

病理性疼痛的神经和化学基础

• 批准号: 8628191
• 负责人: Jun-Ming Zhang
• 金额: $ 39.09万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-12-15 至 2018-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8628191
• 关键词: Acute; Affect; Afferent Neurons; Animals; Attention; Back; Back Pain; Behavior; Behavior assessment; Behavioral; Cells; Chemicals; Chronic; Data; Development; Electrophysiology (science); Frequencies; Ganglia; Generations; Goals; Healthcare; Human; Hypersensitivity; In Vitro; Inflammation; Inflammation Mediators; Inflammation Process; Inflammatory; Injection of therapeutic agent; Interleukin-8; Intervertebral disc structure; Laboratories; Link; Low Back Pain; Mechanics; Mediating; Methods; Microscopy; Modeling; Molecular; Morbidity - disease rate; Motor; Mus; Neurons; Pain; Patients; Pattern; Pharmaceutical Preparations; Play; Pre-Clinical Model; Process; Productivity; Property; Protein Isoforms; Rattus; Research; Role; Sensory; Sensory Ganglia; Small Interfering RNA; Societies; Sodium; Sodium Channel; Spinal Ganglia; Syndrome; Techniques; Testing; United States; Wages; Work; analog; base; behavior measurement; chemokine; chemotherapy; chronic pain; cost; cytokine; human subject; in vivo; interest; knock-down; neuronal excitability; neuropeptide Y; new therapeutic target; novel; oxaliplatin; pain behavior; painful neuropathy; pre-clinical; public health relevance; receptor; relating to nervous system; therapeutic target

DESCRIPTION (provided by applicant): Low back pain is a common problem with high morbidity costs to society, and many patients receive little relief from current therapies. Abnormal spontaneous activity of sensory neurons plays a key role in establishing the chronic pain state in a preclinical model relevant to low back pain, in which pain behaviors are induced by locally inflaming the lumbar dorsal root ganglion (DRG). This activity depends on a particular sodium channel isoform, Nav1.6, which can mediate persistent and resurgent sodium currents that in turn can underlie high- frequency/bursting activity. To date this channel has been largely ignored as a therapeutic target; however, knocking down this channel in the DRG in vivo with small interfering RNA can completely block development of pain behaviors induced by local DRG inflammation, without affecting behavior in the normal animal or motor function. Molecules involved in the inflammation process, such as cytokines/chemokines, have direct effects on sensory neuron excitability and pain. However, the underlying mechanisms are largely unexplored. We hypothesize that local inflammation of the DRG increases expression/release of inflammatory cytokines and enhances high-frequency/bursting discharges by regulating Nav1.6 in a subset of sensory neurons and leads to pain and hypersensitivity. The hypothesis will be tested in 3 Specific Aims: 1) Characterize functional and properties and anatomical distributions of Nav1.6 sodium channel in normal and inflamed sensory ganglia, testing the hypothesis that this channel plays a crucial role in abnormal spontaneous activity by mediating persistent and resurgent currents. Immunostaining methods will be used to test the hypothesis that bursting cells in inflamed ganglia are enriched in Nav1.6+ neurons and in molecules previously linked to pain, such as neuropeptide Y and CGRP. 2) Determine how pro-inflammatory cytokines regulate functional properties of Nav1.6 and Nav1.6-mediated spontaneous activity. We hypothesize that GRO/KC, a chemokine that is up- regulated in several pain models and in human patients with wide-spread pain syndromes, acts to increase spontaneous activity by regulating Nav1.6. 3) Assess the role of Nav1.6 in pathological pain. We will use novel behavioral assessment methods combined with local siRNA knockdown, and selective pharmacological block to determine whether this channel plays a role in the development and persistence of pain after DRG inflammation. Additionally, it will be tested in another back pain model and in a model of neuropathic pain. These aims will be carried out using combined electrophysiological, behavioral, microscopy, and molecular methods. In particular, our laboratory's newly established techniques of manipulating the sensory ganglia in vivo with drugs or small interfering RNAs, in a highly localized fashion, combined with behavioral measurements and electrophysiology, provide a powerful integrated approach to understanding chronic pain mechanisms. Because inflammatory processes play a role in many types of chronic pain, the findings will be relevant not only to understanding low back pain, but other types of pain as well.

描述（由申请人提供）：腰痛是一个常见问题，给社会带来很高的发病成本，并且许多患者从当前的治疗中几乎没有得到缓解。感觉神经元的异常自发活动在与腰痛相关的临床前模型中建立慢性疼痛状态中起着关键作用，在该模型中，疼痛行为是通过腰椎背根神经节（DRG）局部发炎引起的。这种活性取决于特定的钠通道同种型 Nav1.6，它可以介导持续和复活的钠电流，而钠电流反过来又可以成为高频/突发活性的基础。迄今为止，该通道作为治疗靶点在很大程度上被忽视了。然而，用小干扰RNA在体内敲除DRG中的这个通道可以完全阻止局部DRG炎症引起的疼痛行为的发展，而不影响正常动物的行为或运动功能。参与炎症过程的分子，例如细胞因子/趋化因子，对感觉神经元的兴奋性和疼痛有直接影响。然而，其根本机制在很大程度上尚未被探索。我们假设 DRG 的局部炎症增加炎症细胞因子的表达/释放，并通过调节感觉神经元子集中的 Nav1.6 增强高频/爆发性放电，并导致疼痛和过敏。该假设将在 3 个具体目标中得到检验：1) 描述正常和发炎感觉神经节中 Nav1.6 钠通道的功能和特性以及解剖分布，检验该通道通过介导持久性和炎症性反应在异常自发活动中发挥关键作用的假设。复苏的电流。免疫染色方法将用于检验以下假设：发炎神经节中的破裂细胞富含 Nav1.6+ 神经元以及先前与疼痛相关的分子，例如神经肽 Y 和 CGRP。 2) 确定促炎细胞因子如何调节 Nav1.6 的功能特性和 Nav1.6 介导的自发活动。我们假设 GRO/KC（一种在多种疼痛模型和患有广泛疼痛综合征的人类患者中上调的趋化因子）通过调节 Nav1.6 来增加自发活动。 3)评估Nav1.6在病理性疼痛中的作用。我们将使用新颖的行为评估方法结合局部 siRNA 敲低和选择性药理学阻断来确定该通道是否在 DRG 炎症后疼痛的发生和持续中发挥作用。此外，还将在另一个背痛模型和神经性疼痛模型中对其进行测试。这些目标将通过结合电生理学、行为学、显微镜学和分子方法来实现。特别是，我们实验室新建立的用药物或小干扰RNA在体内操纵感觉神经节的技术，以高度局部化的方式，结合行为测量和电生理学，为理解慢性疼痛机制提供了一种强大的综合方法。由于炎症过程在多种类型的慢性疼痛中发挥作用，因此这些发现不仅有助于理解腰痛，而且还有助于理解其他类型的疼痛。