Effects of chronic imipramine and haloperidol treatment on apomorphine-induced motility in rats

Locomotor behavior was studied with the use of automated devices in chronic imipramine- and haloperidol-treated Sprague Dawley rats. The biphasic response to apomorphine was only preserved in the control rats. The response to low dose apomorphine challenge was attenuated by chronic imipramine and haloperidol administration. There were no significant changes in motility responses to high dose apomorphine challenges between the control and experimental groups. The results suggest the involvement of postsynaptic Dopamine receptors (D2) in the loss of response to low dose apomorphine.