Neurotrophic factor regulation of regenerated sensory neuron response properties

神经营养因子对再生感觉神经元反应特性的调节

• 批准号: 7559709
• 负责人: Michael P Jankowski
• 金额: $ 5.17万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-01 至 2010-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7559709
• 关键词: Acute; Afferent Neurons; Axotomy; C Fiber; Cutaneous; Denervation; Fellowship; Fiber; Figs - dietary; GDNF gene; Genetic Transcription; Goals; Growth Factor; Heating; Hyperalgesia; In Vitro; Individual; Injection of therapeutic agent; Injury; Ion Channel; Label; Lead; Link; Mechanics; Mediating; Messenger RNA; Modeling; Molecular; Mus; NGFR Protein; Names; Natural regeneration; Nerve; Nerve Crush; Nerve Growth Factor Receptors; Neurons; Neurotrophic Tyrosine Kinase Receptor Type 1; Nociception; Nociceptors; Pain; Pathway interactions; Peripheral; Peripheral nerve injury; Physiological; Play; Posterior Horn Cells; Preparation; Property; Regulation; Reverse Transcriptase Polymerase Chain Reaction; Role; Sensory; Signal Pathway; Signal Transduction; Skin; Small Interfering RNA; Spinal Cord; Spinal Ganglia; Staining method; Stains; TRPV1 gene; Testing; Time; Tissues; Western Blotting; Work; cell type; chronic pain; in vivo; injured; knock-down; nerve injury; nerve supply; neurotrophic factor; overexpression; protein expression; receptive field; receptor; receptor expression; reinnervation; response; response to injury

DESCRIPTION (provided by applicant): Peripheral nerve injury is known to induce a variety of molecular and physiological changes in primary sensory and dorsal horn neurons. Target derived neurotrophic signaling may play an important role in the injury response. The long-term goal of these studies is to determine how changes in the afferent target regions alter the response properties of dorsal root ganglion (DRG) neurons after nerve injury. We first propose to test the hypothesis that nerve crush and regeneration of saphenous afferents induces altered levels and localization of various neurotrophic factors and their receptors in the skin and DRGs, respectively, over time. Our preliminary evidence suggests that peripheral axotomy induces changes in several neurotrophic factor levels, including NGF and artemin, in the skin, and this correlates to increases in receptors like TRPV1 in the DRGs. In turn, this may underlie our recent finding that nerve injury results in changes in the percentage of TRPV1 containing C-fiber neurons that only respond to heat (CH) after regeneration. For example, high levels of NGF regulate the expression of TRPV1 in dissociated/ axotomized DRG neurons in vitro, and overexpression of artemin in the skin enhances TRPV1 mRNA in the DRGs in vivo. Given that TRPV1, NGF receptor trkA and artemin receptor GFRaS immunostaining overlap extensively in the DRG and each have been linked to pain responses, we then propose to test if GFRaS and/or trkA mediated neurotrophic factor signaling regulates the injury induced changes in the CH neurons. We will be able to correlate the known response properties of regenerated sensory neurons to changes in neurotrophic factor signaling immunocytochemically, and using RT-PCR and western blots before and after reinnervation of the skin, and we will be able to functionally test the role of two particular pathways in establishing the changes in electrophysiological response properties of CH neurons after injury using an ex vivo skin-nerve-DRG-spinal cord preparation after in vivo siRNA mediated knockdown of GFRaS and/or trkA. These studies will allow us to further understand the functional implications of excess growth factor signaling in the skin on injured neurons and how these changes relate to nerve injury induced hyperalgesia. This work may also lead us to better ways to treat injury related chronic pain states.

描述（由申请人提供）：已知周围神经损伤可诱导初级感觉和背角神经元发生多种分子和生理变化。靶源性神经营养信号可能在损伤反应中起重要作用。这些研究的长期目标是确定传入靶区域的变化如何改变神经损伤后背根神经节（DRG）神经元的反应特性。我们首先提出测试的假设，神经挤压和隐传入神经的再生诱导不同的神经营养因子及其受体在皮肤和背根神经节的水平和本地化，分别随着时间的推移。我们的初步证据表明，外周神经切断术诱导的变化，在几个神经营养因子的水平，包括神经生长因子和artemin，在皮肤中，这与增加受体，如TRPV 1在背根神经节。反过来，这可能是我们最近发现的基础，即神经损伤导致含有TRPV 1的C纤维神经元的百分比发生变化，这些神经元在再生后仅对热（CH）做出反应。例如，高水平的NGF在体外调节分离的/轴突切断的DRG神经元中TRPV 1的表达，并且artemin在皮肤中的过表达在体内增强DRG中的TRPV 1 mRNA。鉴于TRPV 1，神经生长因子受体trkA和artemin受体GFRaS免疫染色在DRG中广泛重叠，并且每个都与疼痛反应有关，我们建议测试GFRaS和/或trkA介导的神经营养因子信号传导是否调节CH神经元中损伤诱导的变化。我们将能够将再生感觉神经元的已知反应特性与神经营养因子信号传导的变化相关联，并在皮肤神经再支配前后使用RT-PCR和蛋白质印迹，并且我们将能够使用离体皮肤-神经-DRG在功能上测试两个特定通路在建立损伤后CH神经元的电生理响应特性的变化中的作用，体内siRNA介导的GFRaS和/或trkA敲低后的脊髓制备。这些研究将使我们能够进一步了解皮肤中过量生长因子信号对受损神经元的功能影响，以及这些变化如何与神经损伤诱导的痛觉过敏相关。这项工作也可能使我们找到更好的方法来治疗与损伤相关的慢性疼痛状态。