Ionic mechanisms of TNFalpha-induced sensitization

描述（由申请人提供）：本研究的主要目的是确定肿瘤坏死因子-？- (TNF??)诱导过敏。肿瘤坏死因子?已被确定为一种促伤害、促炎症细胞因子和抗tnf ？药物目前用于治疗疼痛的炎症条件，部分原因可能是由于伤害性信号的调节。TNF的作用机制？调节伤害感觉的机制尚不清楚。最近的研究表明TNF？抗河豚毒素Na+通道亚基Nav1.8的调控。该通道主要存在于检测疼痛刺激的感觉神经元（主要传入伤害感受器）中，并且能够改变背根神经节（DRG）神经元的兴奋性，这一机制可能是行为超敏反应的基础。因此，本提案旨在研究Nav1.8在TNF？-诱导的行为超敏反应，以确定TNF？调节DRG兴奋性，并确定在此过程中Nav1.8的必要性。为此，拟进行的实验将检验Nav1.8在TNF？通过对Nav1.8-/-和野生型同窝小鼠足底注射TNF -后的超敏行为评估，在体内诱导机械和热超敏反应。此外，由于兴奋性增加是维持超敏反应的一种机制，TNF？在体外研究DRG兴奋性的调节。这些实验将测量TNF？并研究p38 MAPK在这一过程中的作用。最后，提出的实验将测试Nav1.8在TNF？通过电生理评估Nav1.8-/-和野生型DRG神经元的各种膜和AP特性来诱导DRG兴奋性的调节。根据美国国立卫生研究院的使命，这些研究是通过了解这些疾病背后的生物机制来确定治疗疼痛疾病的新潜在目标的长期目标的一部分。这些实验可以提高对疼痛的治疗，这是一种影响数百万人的昂贵和虚弱的疾病。？？？？

DESCRIPTION (provided by applicant): The main objective of this study is to identify the mechanism(s) by which tumor necrosis factor-?- (TNF??) induces hypersensitivity. TNF? has been identified as a pro-nociceptive, pro-inflammatory cytokine, and anti-TNF? agents are currently used to treat painful inflammatory conditions which may, in part, be due to modulation of nociceptive signaling. The mechanism by which TNF? modulates nociception remains unknown. Recent work has demonstrated TNF? modulation of the tetrodotoxin-resistant Na+ channel a subunit, Nav1.8. This channel is primarily found in sensory neurons that detect painful stimuli, the primary afferent nociceptors, and is capable of altering excitability of dorsal root ganglia (DRG) neurons, a mechanism that could underlie behavioral hypersensitivity. Therefore, this proposal aims to examine the role of Nav1.8 in TNF? -induced behavioral hypersensitivity, to determine whether TNF? modulates DRG excitability, and to identify the necessity of Nav1.8 in this process. To this end, the proposed experiments will test the necessity of Nav1.8 in TNF? -induced mechanical and thermal hypersensitivity in vivo by behavioral assessment of hypersensitivity in Nav1.8-/- and wild-type littermate mice after intraplantar injection of TNF?. Further, because increased excitability is a mechanism by which hypersensitivity can be maintained, TNF? modulation of DRG excitability in vitro will be examined. These experiments will measure TNF? -induced alterations in excitability and examine the role of p38 MAPK in this process. Finally, the proposed experiments will then test the necessity of Nav1.8 in TNF? -induced modulation of DRG excitability by electrophysiological assessment of various membrane and AP properties in Nav1.8-/- and wild type DRG neurons. In accordance with the mission of the NIH, these studies are part of the long-term objective of identifying new potential targets for the treatment of painful conditions by understanding the biological mechanisms that underlie these conditions. These experiments can lead to enhancements in the treatment of pain, which is a costly and debilitating condition affecting millions of people.????