Antagonism by sulpiride of three apomorphine-induced effects in rodents.

Three effects of apomorphine (hypothermia and climbing behavior in mice, stereotyped behavior in rats) were studied. Sulpiride antagonized the two effects in mice but stereotyped behavior in rats remained unchanged. Pimozide and haloperidol antagonized the three effects. These results could be explained by the existence of two types of dopaminergic receptors or by the different accessibility to identical dopaminergic receptors located in different CNS areas.