Korean J Anesthesiol.  2015 Apr;68(2):170-174. 10.4097/kjae.2015.68.2.170.

Expression of the spinal 5-HT7 receptor and p-ERK pathway in the carrageenan inflammatory pain of rats

Affiliations
  • 1Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School and Hospital, Gwangju, Korea. jichoi@jnu.ac.kr

Abstract

BACKGROUND
Although the inhibitory role of the 5-hydroxytrypatmine receptor 7(5-HT7R) on nociceptive processing is generally recognized, an excitatory effect associated with a reduced 5-HT7R expression has also been observed in the nerve injury model. In the carrageenan model, no significant effect is produced by the 5-HT7R activation, but the change in 5-HT7R expression has not been examined. Lesioning of the spinal serotonergic pathway enhances allodynia in the carrageenan model, but it also relieves several other pain states, including in the formalin model. While lesioning suppresses the activation of the extracellular signal-regulated kinase (ERK) of the spinal cord in the formalin model, its role in the carrageenan model has not been reported.
METHODS
Following intraplantar injections of carrageenan, the spinal 5-HT7R expression was examined using Western blotting in male Sprague-Dawley rats. The effect of serotonergic pathway lesioning with intrathecal 5,7-dihydroxytryptamine (5,7-DHT) on the expression of the phospho-ERK was measured.
RESULTS
The expression of the 5-HT7R in the carrageenan model was not significantly different from that of naive animals. The expression of the spinal p-ERK in the carrageenan model was significantly increased, but returned to the level of a naive rat 1 hour after the carrageenan injection. However, it remained significantly higher 1 hour after the injection in the animals treated with 5,7-DHT than in the naive and control rats.
CONCLUSIONS
The expression of the spinal 5-HT7R is not altered by peripheral inflammation with carrageenan, suggesting that the lack of antinociceptive effect of the 5-HT7R activation is partly attributable to the absence of changes in the expression of the 5-HT7R in the spinal cord. The extended increase of the spinal p-ERK might be related to the enhanced pain behavior in the animals with lesions of the spinal serotonergic pathway in the carrageenan model.

Keyword

5-HT7 receptor; Carrageenan; Extracellular signal-regulated kinase; Spinal cord

MeSH Terms

5,7-Dihydroxytryptamine
Animals
Blotting, Western
Carrageenan*
Formaldehyde
Humans
Hyperalgesia
Inflammation
Male
Phosphotransferases
Rats*
Rats, Sprague-Dawley
Spinal Cord
5,7-Dihydroxytryptamine
Carrageenan
Formaldehyde
Phosphotransferases
Full Text Links
  • KJAE
Actions
Cited
CITED
export Copy
Close
Share
  • Twitter
  • Facebook
Similar articles
Copyright © 2024 by Korean Association of Medical Journal Editors. All rights reserved.     E-mail: koreamed@kamje.or.kr