[Locomotor activity of rats following chronic pretreatment with haloperidol].

The spontaneous locomotor activity, the nocturnal action profile and exploratory behavior following chronic pretreatment with haloperidole was measured (2 mg/kg daily i. p. for 3 weeks). After this treatment all 3 parameters showed significant changes. The mean values of spontaneous activity during the night and the exploratory behavior during the day were strongly enhanced. The nocturnal action profile showed both amplification and a shift of the activity moves. The results give evidence of an increase and alteration of spontaneous motor actions, correlated with a relatively increased activity of the dopaminergic system due to the pretreatment.