Antimycin A-induced mitochondrial dysfunction activates vagal sensory neurons via ROS-dependent activation of TRPA1 and ROS-independent activation of TRPV1

Brain Res. 2019 Jul 15;1715:94-105. doi: 10.1016/j.brainres.2019.03.029. Epub 2019 Mar 23.

Abstract

Inflammation causes activation of nociceptive sensory nerves, resulting in debilitating sensations and reflexes. Inflammation also induces mitochondrial dysfunction through multiple mechanisms. Sensory nerve terminals are densely packed with mitochondria, suggesting that mitochondrial signaling may play a role in inflammation-induced nociception. We have previously shown that agents that induce mitochondrial dysfunction, such as antimycin A, activate a subset of nociceptive vagal sensory nerves that express transient receptor potential (TRP) channels ankyrin 1 (A1) and vanilloid 1 (V1). However, the mechanisms underlying these responses are incompletely understood. Here, we studied the contribution of TRPA1, TRPV1 and reactive oxygen species (ROS) to antimycin A-induced vagal sensory nerve activation in dissociated neurons and at the sensory terminals of bronchopulmonary C-fibers. Nociceptive neurons were defined chemically and genetically. Antimycin A-evoked activation of vagal nociceptors in a Fura2 Ca2+ assay correlated with TRPV1 responses compared to TRPA1 responses. Nociceptor activation was dependent on both TRP channels, with TRPV1 predominating in a majority of responding nociceptors and TRPA1 predominating only in nociceptors with the greatest responses. Surprisingly, both TRPA1 and TRPV1 were activated by H2O2 when expressed in HEK293. Nevertheless, targeting ROS had no effect of antimycin A-evoked TRPV1 activation in either HEK293 or vagal neurons. In contrast, targeting ROS inhibited antimycin A-evoked TRPA1 activation in HEK293, vagal neurons and bronchopulmonary C-fibers, and a ROS-insensitive TRPA1 mutant was completely insensitive to antimycin A. We therefore conclude that mitochondrial dysfunction activates vagal nociceptors by ROS-dependent (TRPA1) and ROS-independent (TRPV1) mechanisms.

Keywords: Antimycin A; C-fiber; Mitochondria; Nociceptor; Reactive oxygen species; TRPA1; TRPV1; Vagal.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Action Potentials / drug effects
  • Animals
  • Antimycin A / pharmacology*
  • Calcium / metabolism
  • Female
  • HEK293 Cells
  • Humans
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mitochondria / drug effects
  • Mitochondria / metabolism*
  • Nociceptors / metabolism
  • Reactive Oxygen Species / metabolism*
  • Sensory Receptor Cells / drug effects
  • Sensory Receptor Cells / metabolism
  • TRPA1 Cation Channel / metabolism*
  • TRPV Cation Channels / metabolism*
  • Transient Receptor Potential Channels / metabolism
  • Vagus Nerve / cytology
  • Vagus Nerve / drug effects
  • Vagus Nerve / metabolism*

Substances

  • Reactive Oxygen Species
  • TRPA1 Cation Channel
  • TRPA1 protein, human
  • TRPV Cation Channels
  • TRPV1 protein, human
  • TRPV1 protein, mouse
  • Transient Receptor Potential Channels
  • Trpa1 protein, mouse
  • Antimycin A
  • Calcium