Pulsed Radiofrequency Application Reduced Mechanical Hypersensitivity and Microglial Expression in Neuropathic Pain Model
Article first published online: 30 JUL 2012
Wiley Periodicals, Inc.
Volume 13, Issue 9, pages 1227–1234, September 2012
How to Cite
Park, H.-W., Ahn, S.-H., Son, J.-Y., Kim, S.-J., Hwang, S.-J., Cho, Y.-W. and Lee, D.-G. (2012), Pulsed Radiofrequency Application Reduced Mechanical Hypersensitivity and Microglial Expression in Neuropathic Pain Model. Pain Medicine, 13: 1227–1234. doi: 10.1111/j.1526-4637.2012.01453.x
- Issue published online: 13 SEP 2012
- Article first published online: 30 JUL 2012
- Pulsed Radiofrequency;
- Neuropathic Pain;
- Mechanical Hypersensitivity;
- Spinal Nerve Ligation
Objective. Pulsed radiofrequency (PRF) procedure has been used in clinical practice for the treatment of chronic neuropathic pain conditions without neuronal damage. The purpose of this study was to investigate the changes in pain response and glial expression after the application of PRF on a dorsal root ganglion (DRG) in a neuropathic pain model.
Design. A neuropathic pain model (14 female Sprague-Dawley [SD] rats; 200–250 g) was made by a unilateral L5 spinal nerve ligation (SNL) and transection on the distal side of the ligation. The development of mechanical and cold hypersensitivity on the hindpaw was established postoperative day 9 (POD 9). The rats were then randomly assigned to the PRF (+) and the PRF (−) groups. Furthermore, PRF (2 bursts/s, duration = 20 milliseconds, output voltage = 45 V) was applied on the ipsilateral DRG for 180 seconds, with a maximum temperature of 42°C, at POD 10. Pain behaviors were tested throughout the 12 days after PRF. We also examined the changes of the spinal glial expression by immunohistochemistry.
Results. Significant reduction of mechanical hypersensitivity in the PRF (+) group was observed from day 1 after a single PRF procedure and was maintained throughout the following 12 days. Immunoreactivity for OX42 in the ipsilateral dorsal horn also decreased compared with that of the PRF (−) group. However, cold hypersensitivity and glial fibrillary acidic protein (GFAP) immunoreactivity in the dorsal horn was not affected by a PRF procedure.
Conclusions. Our result demonstrated that the mechanical hypersensitivity, induced by L5 SNL, was attenuated by a PRF procedure on the ipsilateral DRG. This analgesic effect may be associated with an attenuation of the microglial activation in the dorsal horn.