Protein kinase C is partly involved in c-fos protein expression of nocuously-activated neurons but may not in concomitant modulatory action through opioid receptors at the spinal level in rats.
- Author:
Hong NIE
1
;
Hang WANG
;
Rui-Xin ZHANG
;
Wang-Cai GAO
;
Jian-Tian QIAO
Author Information
1. Department of Neurobiology, Shanxi Medical University, Taiyuan, Shanxi 030001, China.
- Publication Type:Journal Article
- MeSH:
Animals;
Formaldehyde;
pharmacology;
Immunohistochemistry;
Male;
Naloxone;
pharmacology;
Narcotic Antagonists;
pharmacology;
Nociceptors;
physiology;
Pain;
metabolism;
physiopathology;
Posterior Horn Cells;
physiology;
Protein Kinase C;
metabolism;
physiology;
Proto-Oncogene Proteins c-fos;
biosynthesis;
physiology;
Random Allocation;
Rats;
Rats, Sprague-Dawley;
Receptors, Opioid, delta;
agonists;
Spinal Cord;
physiology
- From:
Acta Physiologica Sinica
2004;56(4):455-460
- CountryChina
- Language:English
-
Abstract:
The present study was aimed to examine if protein kinase C (PKC) activation is necessarily involved in both the c-fos protein expression in the nocuously-activated c-fos protein-like immunoreactive (Fos-LI) neurons and the concomitant opioid receptor-mediated modulation in the dorsal horn circuitry of the spinal cord. Formalin was injected into a hindpaw of rats 5 min after the rats were pretreated with intrathecal (i.t.) administration of chelerythrine (Chel), an inhibitor of PKC, naloxone (Nal), combined administration of these two (Chel + Nal), or vehicle (n=5 in each group),respectively. By using immunocytochemical techniques, the formalin-induced Fos-LI neurons in the lumbar dorsal horn were calculated 1 h after formalin injection. The results showed that: (1) i.t. Chel significantly reduced the number of Fos-LI neurons in the dorsal horn of the spinal cord on the side ipsilateral to the formalin injection, showing a decrease by 60.3% (P<0.001) as compared to that observed in the i.t.vehicle group; (2) i.t. Nal significantly increased the number of Fos-LI neurons in the ipsilateral dorsal horn, with an increase of 46.0% (P<0.01) as compared to that in the i.t.vehicle group, the highest percentage increase being found in the deeper laminae of the dorsal horn; and (3) i.t. Chel + Nal also exhibited a significant decrease in Fos-LI neurons in the ipsilateral dorsal horn as compared to i.t. Nal group, showing a reduction of 53.2%, a value similar to that in the i.t. Chel group. These results suggest that: (1) PKC plays a role in the c-fos protein expression only in nearly one half of the Fos-LI neurons in the dorsal horn; and (2) PKC is possibly not involved in the concomitant modulation on the nociception mediated by micro- (and also partly delta-) opioid receptors in the spinal cord.
