The Effect of Intrathecal Morphine, Clonidine and MK801 on the Formalin Test in the Rats.
10.4097/kjae.1997.32.3.354
- Author:
Jae Youn KWON
1
;
Chul Hong KIM
;
Hae Kyu KIM
;
Seong Wan BAIK
;
Inn Se KIM
;
Kyoo Sub CHUNG
Author Information
1. Department of Anesthesiology, Pusan National University Hospital, Pusan, Korea.
- Publication Type:Original Article
- Keywords:
Analgesics;
clonidine;
MK801;
morphine;
Anesthetic technique;
intrathecal;
Animals;
rats;
Pain;
formalin test;
flinching;
wind-up
- MeSH:
Analgesics;
Anesthesia;
Animals;
Catheters;
Chronic Pain;
Clonidine*;
Dizocilpine Maleate*;
Formaldehyde*;
Hyperalgesia;
Morphine*;
Pain Measurement*;
Rats*
- From:Korean Journal of Anesthesiology
1997;32(3):354-359
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
BACKGROUND: There has been much interest in the involvement of wind-up in the hyperalgesia and allodynia of chronic pain syndrome. To investigate the behavioral parallels of this wind-up phenomenon, we evaluated the effects of intrathecal morphine, clonidine and MK801 on the formalin test in the rats. METHOD: All experimental animals were divided randomly into six groups. In group 1(n=7), normal saline 50 l was administered through the intrathecal catheter(PE10, 8 cm in length). In group 2(n=7), morphine 10 g was administered through the catheter. In group 3(n=7), group 4(n=7), group 5(n=7) and group 6(n=7), clonidine 10 g, clonidine 20 g, MK801 1 g, MK801 10 g was administered in same manner, respectively. Thirty min after recoverying from anesthesia, 50 l 5% formalin was injected in the hind paw. To quantify the formalin response, we counted the number of spontaneous flinching for 60 min. RESULT: Intrathecal morphine(group 2) decreased the number of paw flinches in both phases 1 and 2 readily compared to control(p<0.05). In the clonidine(group 3 and 4), both groups decreased the number of flinching in both phases 1 and 2, but there was no significant difference between two groups. In group 5, intrathecal MK-801 decreased the number of paw flinches in phase 2. In group 6, intrathecal MK-801 decreased the number of paw flinches in both phases 1 and 2. CONCLUSION: This study suggest that wind-up is readily blocked by pretreatment of morphine, clonidine and MK801.
