Antagonism of clonidine antinociception by buspirone and 1-(2-pyrimidinyl)-piperazine.
The effects of pretreatment with buspirone and its major metabolite 1-(2-pyrimidinyl)-piperazine (1-PP) on antinociception produced by clonidine were investigated in mice. Buspirone and 1-PP dose dependently attenuated the antinociceptive action of s.c. administered clonidine in the writhing and tail-flick assays. In both assays, 1-PP was more potent than buspirone in antagonizing clonidine-induced antinociception. After s.c. pretreatment with buspirone (8 mg/kg) and 1-PP (4 mg/kg), the antinociceptive ED50 values of s.c. clonidine were significantly increased. The antagonistic effects of buspirone and 1-PP on clonidine-induced antinociception may be due to their alpha 2-adrenoceptor antagonist activity.
Department of Pharmacology, Hunan Institute of Pharmaceutical Industry, Changsha, People's Republic of China.
B J
BJ
Cao
W P
WP
Li
D000700:Analgesics / Q000037:antagonists & inhibitors*; D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D002065:Buspirone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D003000:Clonidine / Q000037:antagonists & inhibitors*; D008297:Male; D051379:Mice
D000700:Analgesics; D014151:Anti-Anxiety Agents; C037921:1-(2-pyrimidinyl)piperazine; D003000:Clonidine; D002065:Buspirone