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trkA is expressed in nociceptive neurons and influences electrophysiological properties via Nav1.8 expression in rapidly conducting nociceptors.
- Source :
-
The Journal of neuroscience : the official journal of the Society for Neuroscience [J Neurosci] 2005 May 11; Vol. 25 (19), pp. 4868-78. - Publication Year :
- 2005
-
Abstract
- To test the hypothesis that trkA (the high-affinity NGF receptor) is selectively expressed in nociceptive dorsal root ganglion (DRG) neurons, we examined the intensity of trkA immunoreactivity in single dye-injected rat DRG neurons, the sensory receptor properties of which were identified in vivo with mechanical and thermal stimuli. We provide the first evidence in single identified neurons that strong trkA expression in DRGs is restricted to nociceptive neurons, probably accounting for the profound influence of NGF on these neurons. Furthermore, we demonstrate that trkA expression is as high in rapidly conducting (Aalpha/beta) as in more slowly conducting (Adelta and C) nociceptors. All Aalpha/beta low-threshold mechanoreceptors (LTMs) are trkA negative, although weak but detectable trkA is present in some C and Adelta LTMs. NGF can influence electrophysiological properties of DRG neurons, probably by binding to trkA. We found positive correlations for single identified Aalpha/beta (but not C or Adelta) nociceptors between trkA immunocytochemical intensity and electrophysiological properties typical of nociceptors, namely long action potential and afterhyperpolarization durations and large action potential amplitudes. Furthermore, for Aalpha/beta (notCorAdelta) nociceptors, trkA intensity is inversely correlated with conduction velocity. Similar relationships, again only in Aalpha/beta nociceptors, between electrophysiological properties and trkA expression exist for sodium channel Nav1.8 but not Nav1.9 immunoreactivities. These findings suggest that in Aalpha/beta nociceptors, influences of NGF on expression levels of Nav1.8 are related to, and perhaps limited by, expression levels of trkA. This view is supported by a positive correlation between immuno-intensities of trkA and Nav1.8 in A-fiber, but not C-fiber, nociceptors.
- Subjects :
- Action Potentials drug effects
Animals
Cell Count methods
Cell Size
Diagnostic Imaging methods
Female
Immunohistochemistry methods
In Vitro Techniques
Isoquinolines
NAV1.8 Voltage-Gated Sodium Channel
NAV1.9 Voltage-Gated Sodium Channel
Nerve Fibers, Myelinated physiology
Nerve Fibers, Unmyelinated physiology
Neural Conduction physiology
Neural Conduction radiation effects
Neurons classification
Neurons drug effects
Neuropeptides physiology
Organometallic Compounds
Organophosphorus Compounds
Rats
Rats, Wistar
Sodium Channel Blockers pharmacology
Sodium Channels physiology
Statistics, Nonparametric
Tetrodotoxin pharmacology
Action Potentials physiology
Ganglia, Spinal cytology
Nerve Tissue Proteins metabolism
Neurons physiology
Nociceptors physiology
Receptor, trkA metabolism
Sodium Channels metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1529-2401
- Volume :
- 25
- Issue :
- 19
- Database :
- MEDLINE
- Journal :
- The Journal of neuroscience : the official journal of the Society for Neuroscience
- Publication Type :
- Academic Journal
- Accession number :
- 15888662
- Full Text :
- https://doi.org/10.1523/JNEUROSCI.0249-05.2005