Spinal Cord-Mediated Acute Neurogenic Inflammation

描述(申请人提供)：神经源性炎症导致许多临床相关状态，包括关节炎、炎症性肠病、慢性支气管炎、偏头痛和间质性膀胱炎。已知这种类型的炎症是由感觉神经末梢释放的炎性物质引起的，由此可能引起疼痛，甚至加剧。为了探讨其作用机制，我们用辣椒素(CAP)皮内注射建立了神经源性炎症的急性模型。本研究的长期目标是阐明神经源性炎症是如何通过激活瞬时受体电位香草酸-1(TRPVO)受体，然后通过触发中枢介导的逆行活动而维持的，背根反射(DRR)加剧炎症性疼痛，以及交感-感觉相互作用如何调节神经源性炎症。揭示这些机制将导致抗炎疗法的改进。本方案的总体假设是，通过皮内注射CAP或组织损伤激活TRPV-I受体可引发神经源性炎症，然后通过触发DRRs维持和发展这种炎症。交感-感觉相互作用通过激活蛋白激酶C(PKC)等信号转导通路来调节TRPVi受体的功能活性，从而调节神经源性炎症。具体目的1是确定注射CAP后的神经源性炎症是否涉及触发DRRs，从而导致初级传入伤害性感受器释放降钙素基因相关肽和/或P物质，以及这一过程是否会反过来增强CAP诱导的初级传入伤害性感受器的敏化，以及分析这一过程是否由TRPN/！感受器。具体目的2是检查是否激活了Px/！初级传入伤害性感受器上的受体通过激活背角回路中的GABA能中间神经元，在增强DRRS中起重要作用。具体目的3是确定当神经源性炎症发生和发展时，初级传入神经元中是否发生了PKC的磷酸化，以及PKC的磷酸化是否上调了TRPN/T受体。具体目的4是研究去甲肾上腺素和5‘-三磷酸腺苷的释放对神经源性炎症的交感神经效应是否通过PKC级联调节TRPNA受体的功能来实现。将使用的实验方法包括电生理记录和参与伤害性信号转导的蛋白质的药物调节，血流量和足爪厚度的测量以反映CAP诱导的神经源性炎症，以及免疫组织化学和Western blotting研究CAP注射前后磷酸化受体和PKC表达的变化。

DESCRIPTION (provided by applicant): Neurogenic inflammation contributes to many clinically relevant states, including arthritis, inflammatory bowel disease, chronic bronchitis, migraine and interstitial cystitis. Such a type of inflammation has been known to be initiated by release of inflammatory substances from sensory nerve terminals by which painful sensation may be caused and even exacerbated. In order to investigate its mechanisms, we have experimentally established an acute model of neurogenic inflammation by using an intradermal capsaicin (CAP) injection. The long-term goal of the proposed studies is to elucidate how neurogenic inflammation is initiated by activation of transient receptor potential vanilloid-1 (TRPVO receptors, then maintained by triggering the centrally mediated antidromic activity, dorsal root reflexes (DRRs) to exacerbate inflammatory pain, and how sympathetic-sensory interactions modulate the neurogenic inflammation. Uncovering these mechanisms will lead to improvements in anti-inflammatory therapies. The overall hypothesis of the present proposal is that activation of TRPV-i receptors either by intradermal injection of CAP or tissue injury initiates neurogenic inflammation that will then be maintained and develops by triggering DRRs. Sympathetic-sensory interactions modulate the neurogenic inflammation by regulating the functional activity of TRPVi receptors via activating signal transduction cascades, such as protein kinase C (PKC). Specific Aim 1 is to determine if neurogenic inflammation following CAP injection involves triggering DRRs that cause the release of calcitonin gene-related peptide and/or substance P from primary afferent nociceptors and if this process would in turn enhance the CAP-induced sensitization of primary afferent nociceptors, as well as analyze if this process is initiated by activation of TRPN/! receptors. Specific Aim 2 is to examine if activation of the PX/! receptors in primary afferent nociceptors plays an important role in enhancing DRRs by activating GABAergic interneurons in dorsal horn circuits. Specific Aim 3 is to determine if phosphorylation of PKC takes place in the primary afferent neurons when neurogenic inflammation is initiated and develops, and if TRPN/T receptors are up-regulated by the phosphorylation of PKC. Specific Aim 4 is to examine if sympathetic effects on neurogenic inflammation by release of norepinephrine and adenosine 5'-triphosphate are done by modulating the function of TRPNA, receptors via the PKC cascade. The experimental approaches that will be used include electrophysiological recordings and pharmacological modulation of proteins involved in nociceptive signal transduction, blood flow and paw-thickness measurements to reflect neurogenic inflammation induced by CAP injection, and immunohistochemical and Western blotting studies to analyze changes in the expression of phosphorylated receptors and PKC before and after CAP injection.