Apomorphine as a discriminative stimulus, and its antagonism by haloperidol

At a non-stereotypogenic dose (0.16 mg/kg, s.c.), apomorphine was shown to produce a discriminative stimulus in rats. The apomorphine-produced stimulus was found to be effectively antagonized by haloperidol. It is suggested that apomorphine's ability to stimulate central dopamine receptors is directly related to its cueing action.