| Peripheral Analgesic Effect of Ketamine in Rat Formalin Test. |
|
Young Woo Cho, Sun Ok Song, Dong Kuk Ahn, Jae Yong Lee |
1Department of Anesthesiology and Pain Medicine, Yeungnam University, Daegu, Korea. sosong@med.yu.ac.kr
2Department of Anesthesiology and Pain Medicine, College of Medicine, University of Ulsan, Ulsan, Korea.
3Department of Oral Physiology and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, Korea. |
|
|
|
|
|
| Abstract |
BACKGROUND
This study was performed to compare the analgesic effects of the systemic versus local administration of ketamine and observe the effects of an NMDA receptor agonist on its peripheral analgesia using the rat formalin test.
METHODS
Rats undergoing peripheral analgesia were divided into three groups; the administration of a subcutaneous (s.c.) injection of 0.1 ml of normal saline (Control), and intraperitoneal (i.p.) (Keta/IP) and s.c. (Keta/LO) injections of 2.5 mg/0.1 ml of ketamine administered 5 min before a s.c. injection of 50 ul of 5% formalin. All s.c.
injections were performed at the same site: the right hind paw of the rat. To observe the effects of an NMDA receptor agonist, five groups were compared. In addition to the control and Keta/LO groups described above, following three groups with 1-Aminocyclopropanecarboxylic acid (ACPC), an NMDA receptor agonist, in addition to the Keta/LO group; local infiltration with 0.1 mM/0.1 ml ACPC 10 min before or after the administration of ketamine, and an i.p. injection 10 min before the administration of ketamine followed by a s.c. injection of formalin 5 min later. The pain behavior was compared according to the number of flinches during phase 2.
RESULTS
All the ketamine groups showed fewer flinches compared to the control (P < 0.01). The Keta/Lo group showed fewer flinches than that of the Keta/IP group (P < 0.01).
The analgesic effect of locally administered ketamine was reversed by pretreatment with either s.c. or i.p. ACPC, but not by post-treatment.
CONCLUSIONS
These data suggest that locally administered ketamine has a potent peripheral analgesic effect, but the administration of ACPC prior to ketamine decreases the analgesic effect of ketamine. |
| Key Words:
formalin test; ketamine; NMDA agonist; peripheral analgesia |
|
PDF Links
Full text via DOI
Download Citation
