Korean J Pain.  2013 Jul;26(3):255-264. 10.3344/kjp.2013.26.3.255.

The Effects of Pre-emptive Administration of Ketamine and norBNI on Pain Behavior, c-Fos, and Prodynorphin Protein Expression in the Rat Spinal Cord after Formalin-induced Pain Is Modulated by the DREAM Protein

• Long I
• Suppian R
• Ismail Z

• KMID: 2074026
• DOI: http://doi.org/10.3344/kjp.2013.26.3.255

Abstract

BACKGROUND
We investigated the effects of pre-emptive administration of ketamine and norBNI on pain behavior and the expression of DREAM, c-Fos, and prodynorphin proteins on the ipsilateral side of the rat spinal cord at 2 and 4 hours after formalin injection.
METHODS
Eighty-four male Sprague Dawley rats were divided into 4 major groups consisting of control rats (C) (n = 12), rats given only formalin injections (F) (n = 24), and rats treated with pre-emptive administration of either ketamine (K+F) (n = 24) or norBNI (N+F) (n = 24). The non-control groups were further divided into subgroups consisting of rats that were sacrificed at 2 and 4 hours (n = 12 for each group) after formalin injection. Pain behavior was recorded for 1 hour. After 2 and 4 hours, the rats were sacrificed and the spinal cords (L4-L5 sections) were removed for immunohistochemistry and Western blot analysis.
RESULTS
The pain behavior response was reduced in the K+F group compared to the other groups during the second phase of the formalin pain response. We detected an increase in the nuclear DREAM protein level in the K+F group at 2 and 4 hours and a transient decrease in the N+F group at 2 hours; however, it increased at 4 hours after injection. Fos-like immunoreactivity (FLI) and Prodynorphin-like immunoreactivity (PLI) neurons decreased in the K+F group but increased in the N+F group at 2 hours after injection. While FLI decreased, PLI increased in all groups at 4 hours after injection.
CONCLUSIONS
We suggest that NMDA and kappa opioid receptors can modulate DREAM protein expression, which can affect pain behavior and protein transcriptional processes at 2 hours and bring about either harmful or protective effects at 4 hours after formalin injection.

Keyword

DREAM protein; formalin test; kappa opioid receptor; NMDA receptor; rat spinal cord

MeSH Terms

Animals
Blotting, Western
Enkephalins
Formaldehyde
Humans
Immunohistochemistry
Ketamine
Male
N-Methylaspartate
Neurons
Pain Measurement
Protein Precursors
Proteins
Rats
Rats, Sprague-Dawley
Receptors, Opioid, kappa
Spinal Cord
Enkephalins
Formaldehyde
Ketamine
N-Methylaspartate
Protein Precursors
Proteins
Receptors, Opioid, kappa