Chronic Compression of Mouse Dorsal Root Ganglion Alters Voltage-Gated Sodium and Potassium Currents in Medium-Sized Dorsal Root Ganglion Neurons

J Neurophysiol. 2011 Dec;106(6):3067-72. doi: 10.1152/jn.00752.2011. Epub 2011 Sep 14.

Abstract

Chronic compression (CCD) of the dorsal root ganglion (DRG) is a model of human radicular pain produced by intraforaminal stenosis and other disorders affecting the DRG, spinal nerve, or root. Previously, we examined electrophysiological changes in small-diameter lumbar level 3 (L3) and L4 DRG neurons treated with CCD; the present study extends these observations to medium-sized DRG neurons, which mediate additional sensory modalities, both nociceptive and non-nociceptive. Whole-cell patch-clamp recordings were obtained from medium-sized somata in the intact DRG in vitro. Compared with neurons from unoperated control animals, CCD neurons exhibited a decrease in the current threshold for action potential generation. In the CCD group, current densities of TTX-resistant and TTX-sensitive Na(+) current were increased, whereas the density of delayed rectifier voltage-dependent K(+) current was decreased. No change was observed in the transient or "A" current after CCD. We conclude that CCD in the mouse produces hyperexcitability in medium-sized DRG neurons, and the hyperexcitability is associated with an increased density of Na(+) current and a decreased density of delayed rectifier voltage-dependent K(+) current.

Publication types

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

MeSH terms

  • Analysis of Variance
  • Animals
  • Biophysics
  • Disease Models, Animal
  • Electric Stimulation
  • Functional Laterality
  • Ganglia, Spinal / pathology*
  • In Vitro Techniques
  • Ion Channel Gating / drug effects
  • Ion Channel Gating / physiology*
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Mice
  • Neurons / classification
  • Neurons / drug effects
  • Neurons / metabolism*
  • Patch-Clamp Techniques
  • Potassium Channel Blockers / pharmacology
  • Potassium Channels, Voltage-Gated / metabolism*
  • Radiculopathy / pathology*
  • Sodium Channel Blockers / pharmacology
  • Sodium Channels / metabolism*
  • Tetraethylammonium / pharmacology
  • Tetrodotoxin / pharmacology

Substances

  • Potassium Channel Blockers
  • Potassium Channels, Voltage-Gated
  • Sodium Channel Blockers
  • Sodium Channels
  • Tetrodotoxin
  • Tetraethylammonium