The possible involvement of GABAA systems in the antinarcotic effect of majonoside-R2, a major constituent of Vietnamese ginseng, in mice.
The effect of majonoside-R2 on morphine- and U-50,488H-induced antinociception was examined by the tail-pinch test in mice and compared with that of diazepam. Majonoside-R2 and diazepam inhibited the morphine- and U-50,488H-induced antinociception, and the actions were antagonized by the benzodiazepine receptor antagonist flumazenil and the GABA-gated CI- channel blocker picrotoxin. Diazepam but not majonoside-R2 exhibited a protective activity against convulsion caused by the GABAA antagonists bicuculline and picrotoxin. These results indicate that GABAA systems are involved in the effect of majonoside-R2 on the opioid-induced antinociception and suggest that the mechanisms of action of majonoside-R2 may differ from those of diazepam.
Nguyen
T T
TT
Division of Pharmacology, Research Institute for Wakan-Yaku (Oriental Medicines), Toyama Medical and Pharmaceutical University, Japan.
Matsumoto
K
K
Yamasaki
K
K
Nguyen
M D
MD
Nguyen
T N
TN
Watanabe
H
H
D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000700:Analgesics / Q000037:antagonists & inhibitors; D000701:Analgesics, Opioid / Q000037:antagonists & inhibitors; D000704:Analysis of Variance; D000818:Animals; D003292:Convulsants; D003975:Diazepam / Q000037:antagonists & inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005442:Flumazenil / Q000494:pharmacology; D018757:GABA Modulators / Q000037:antagonists & inhibitors / Q000494:pharmacology; D036145:Ginsenosides; D008297:Male; D051379:Mice; D009020:Morphine / Q000037:antagonists & inhibitors; D010147:Pain Measurement / Q000187:drug effects*; D010852:Picrotoxin; D011759:Pyrrolidines / Q000037:antagonists & inhibitors; D012503:Saponins / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000700:Analgesics; D000701:Analgesics, Opioid; D003292:Convulsants; D003975:Diazepam; D005442:Flumazenil; D018757:GABA Modulators; D036145:Ginsenosides; D009020:Morphine; D010852:Picrotoxin; D011759:Pyrrolidines; D012503:Saponins; C098043:majonoside R2