Antinociceptive effect of intrathecal ginsenosides through alpha-2 adrenoceptors in the formalin test of rats.
Br J Anaesth
; 106(3): 371-9, 2011 Mar.
Article
in En
| MEDLINE
| ID: mdl-21169610
ABSTRACT
BACKGROUND:
We defined the nature of the pharmacological interaction after intrathecal co-administration of ginsenosides with clonidine, and clarified the contribution of the α-2 adrenoceptors on the effect of ginsenosides.METHODS:
Pain was evoked by injection of a formalin solution (5%, 50 µl) into the hindpaw of male Sprague-Dawley rats. Isobolographic analysis was performed to characterize the drug interaction between ginsenosides and clonidine. The antagonism of ginsenosides-mediated antinociception was determined with α-2A (BRL 44408), α-2B (ARC 239), and α-2C (JP 1302) adrenoceptor antagonists. The expression of α-2 adrenoceptor subtypes was examined by reverse transcriptase-polymerase chain reaction.RESULTS:
Intrathecal ginsenosides (n=29) and clonidine (n=31) displayed an antinociceptive effect. The ED(50) values (95% confidence intervals) of ginsenosides and clonidine for phases 1 and 2 were 109.5 (63-190.3) and 110.9 (57.1-215.5), and 11.8 (3.7-37.1) and 4.9 (3.1-6.7) µg, respectively. With an isobolographic study (n=48), the ED(50) values (95% confidence intervals) of ginsenosides in the combination of ginsenosides and clonidine for phases 1 and 2 were 58.2 (38.9-87.3) and 57.2 (46.5-70.3) µg, respectively. Intrathecal BRL 44408 (n=6), ARC 239 (n=5), and JP 1302 (n=5) reversed the antinociception of ginsenosides in both phases (P<0.01, <0.001). The injection of formalin increased the expression of α-2C adrenoceptor in the spinal cord (P<0.05).CONCLUSIONS:
Intrathecal ginsenosides additively interacted with clonidine in the formalin test. Furthermore, α-2A, -B, and -C adrenoceptors contributed to the antinociception of intrathecal ginsenosides.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Pain
/
Clonidine
/
Receptors, Adrenergic, alpha-2
/
Analgesics, Non-Narcotic
/
Ginsenosides
Limits:
Animals
Language:
En
Journal:
Br J Anaesth
Year:
2011
Document type:
Article