Piperoxane reduces the effects of clonidine on aggression in mice and on noradrenaline dependent hypermotility in rats

Aggression in isolated male mice and hypermotility in rats produced by the noradrenaline releaser H 77/77 were studied after the s.c. administration of the alpha-adrenergic agonist clonidine and the alpha-antagonist piperoxane. Clonidine 0.005--0.5 mg/kg inhibited both behaviours while piperoxane showed a weak and short-lasting antiaggressive effect and no H 77/77 antagonism. Inactive doses of piperoxane reduced the inhibitory effects of clonidine. The results indicate that isolation-induced aggression in mice and H 77/77-induced hypermotility in rats are behavioural signs related to the availability of noradrenaline at the receptor.