Korean J Pain.  2008 Apr;21(1):11-17. 10.3344/kjp.2008.21.1.11.

The Expression of the Ca++ Channel alpha2delta Subunit and TRPM8 in the Dorsal Root Ganglion of Sympathetically Maintained Pain and Sympathetic Independent Pain Rat Models

• Han DW
• Kweon TD
• Kim YA
• Choi JB
• Lee YW

• KMID: 1480640
• DOI: http://doi.org/10.3344/kjp.2008.21.1.11

Abstract

BACKGROUND: Peripheral nerve injury induces up-regulation of the calcium channel alpha2delta (alpha2delta) subunit and TRPM8 in the dorsal root ganglion (DRG) which might contribute to allodynia development. We investigated the expression of the alpha2delta subunit and TRPM8 in the DRG of sympathetically maintained pain (SMP) and sympathetic independent pain (SIP) rat model.
METHODS
For the SMP model, the L5 and L6 spinal nerves were ligated tightly distal to the DRG. For the SIP model, the tibial and sural nerves were transected, while the common peroneal nerve was spared. After a 7 day postoperative period, tactile and cold allodynia were assessed using von Frey filaments and acetone drops, respectively. Expression of the alpha2delta subunit and TRPM8 in the L5 and L6 DRG were subsequently examined by a Western blot.
RESULTS
There were no significant differences between the two models for the thresholds of tactile and cold allodynia. Expression of the alpha2delta subunit in the ipsilateral DRG to the injury was increased as determined on a Western blot as compared to that in the contralateral or sham-operated DRG of the SMP model, but there was no difference in expression seen with the use of the SIP model. There was no difference in the expression of TRPM8 in the ipsilateral DRG to the injury and the contralateral or sham-operated DRG of either model.
CONCLUSIONS
Up-regulation of the alpha2delta subunit in injured DRG may play a role that contributes to tactile allodynia development in SMP, but not TRPM8 to cold allodynia after peripheral nerve injury.

Keyword

alpha2delta subunit; dorsal root ganglion; SIP; SMP; TRPM8

MeSH Terms

Acetone
Animals
Blotting, Western
Calcium Channels
Cold Temperature
Diagnosis-Related Groups
Ganglia, Spinal
Hyperalgesia
Organic Chemicals
Peripheral Nerve Injuries
Peroneal Nerve
Polyenes
Postoperative Period
Rats
Spinal Nerve Roots
Spinal Nerves
Sural Nerve
Up-Regulation
Acetone
Calcium Channels
Organic Chemicals
Polyenes