The influence of early postnatal treatment with haloperidol on the effects induced by small and large doses of apomorphine on locomotion of adult rats.

ABSTRACT

Chronic administration of haloperidol (0.5 mg/kg, s.c.) during early postnatal life did not modify the effects produced by a small dose of apomorphine (0.02 mg/kg, s.c.) on the locomotor activity of adult rats; conversely, the reduction of locomotion induced by a large dose of apomorphine (1 mg/kg, s.c.) was much more kared in haloperidol-pretreated rat than in saline-pretreated ones. The differential ontogeny of dopamine auto- and postsynaptic receptors could be partly responsible for the different influence of postnatal treatment with haloperidol on the responsiveness of the adult to small and large doses of apomorphine.