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Sensory discrimination between innocuous and noxious cold by TRPM8-expressing DRG neurons of rats.
- Source :
-
Molecular Pain . 2012, Vol. 8 Issue 1, p79-88. 10p. 6 Diagrams, 1 Chart. - Publication Year :
- 2012
-
Abstract
- The TRPM8 channel is a principal cold transducer that is expressed on some primary afferents of the somatic and cranial sensory systems. However, it is uncertain whether TRPM8-expressing afferent neurons have the ability to convey innocuous and noxious cold stimuli with sensory discrimination between the two sub-modalities. Using rat dorsal root ganglion (DRG) neurons and the patch-clamp recording technique, we characterized membrane and action potential properties of TRPM8-expressing DRG neurons at 24°C and 10°C. TRPM8-expressing neurons could be classified into TTX-sensitive (TTXs/TRPM8) and TTX-resistant (TTXr/TRPM8) subtypes based on the sensitivity to tetrodotoxin (TTX) block of their action potentials. These two subtypes of cold-sensing cells displayed different membrane and action potential properties. Voltage-activated inward Na+ currents were highly susceptible to cooling temperature and abolished by ~95% at 10°C in TTXs/TRPM8 DRG neurons, but remained substantially large at 10°C in TTXr/TRPM8 cells. In both TTXs/TRPM8 and TTXr/TRPM8 cells, voltage-activated outward K+ currents were substantially inhibited at 10°C, and the cooling-sensitive outward currents resembled A-type K+ currents. TTXs/TRPM8 neurons and TTXr/TRPM8 neurons were shown to fire action potentials at innocuous and noxious cold temperatures respectively, demonstrating sensory discrimination between innocuous and noxious cold by the two subpopulations of cold-sensing DRG neurons. The effects of cooling temperatures on voltage-gated Na+ channels and A-type K+ currents are likely to be contributing factors to sensory discrimination of cold by TTXs/TRPM8 and TTXr/TRPM8 afferent neurons. [ABSTRACT FROM AUTHOR]
- Subjects :
- *NEURONS
*COLD (Temperature)
*LABORATORY rats
*LABORATORY animals
*ELECTROPHYSIOLOGY
Subjects
Details
- Language :
- English
- ISSN :
- 17448069
- Volume :
- 8
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Molecular Pain
- Publication Type :
- Academic Journal
- Accession number :
- 84188071
- Full Text :
- https://doi.org/10.1186/1744-8069-8-79