Korean J Anesthesiol.  2000 May;38(5):894-903. 10.4097/kjae.2000.38.5.894.

The Effects of Transection Injury and Local Infiltration of Phenol at the Sciatic Nerve on c-fos Expression in the Spinal Cords of Rats

• Lim HK
• Chung CK
• Kim TJ
• Shin JK
• Cha YD
• Park DH
• Seung IS
• Han JU

• KMID: 1936305
• DOI: http://doi.org/10.4097/kjae.2000.38.5.894

Abstract

BACKGROUND: Phenol has effects like surgical neurectomy, but may evoke pain after local infiltration in nerves. Transection of peripheral nerves may induce neuropathic pain through increased spontaneous discharge and other mechanisms. Proto-oncogene, c-fos, is an indicator of neuronal activity, and its expression in the spinal cord may be related to pain development, because inhibition of c-fos expression has corresponding effects like analgesia. We evaluated the effects of local infiltration of phenol and transection injury at the sciatic nerve on c-fos expression in the spinal cords of rats.
METHODS
Sixteen male Sprague-Dawley rats were divided into 2 groups; transection of the sciatic nerve was performed for group 1; phenol was infiltrated into the sciatic nerve in group 2. Three hours, 1 week, 2 weeks, and 3 weeks after the experiment, the corresponding spinal cord was stained immunohistochemically for c-fos.
RESULTS
c-fos was expressed from 3 hours to 2 weeks over the laminae of the dorsal horn in each group. Phenol increased the expression of c-fos initially, but decreased 1 week later. Transection injury did not increase it initially, but showed the peak expression at 1 week, and maintained it for 2 weeks. Therefore, it seems that phenol, rather than the transection injury, stimulates c-fos expression early, but decreases later.
CONCLUSIONS
Phenol treatment, caused by chemical block due to protein denaturation and nonspecific inflammation, may induce less neuropathic pain than the transection of a nerve.

Keyword

Spinal cord: c-fos; laminae of dorsal horn; Toxicity: phenol

MeSH Terms

Analgesia
Animals
Horns
Humans
Inflammation
Male
Neuralgia
Neurons
Peripheral Nerves
Phenol*
Protein Denaturation
Proto-Oncogenes
Rats*
Rats, Sprague-Dawley
Sciatic Nerve*
Spinal Cord*
Phenol