NEUROLEPTICS DIFFERENTIALLY MODULATE CENTRAL DOPAMINE D-1-RECEPTOR BINDING

THE effect of the classical neuroleptic, fluphenazine, on dopamine D-1 -receptor binding was examined in different regions of the basal gangl ia. Whereas exposure to fluphenazine for 18 months reduced [I-125]SCH- 23982 binding to D-1-receptors in the caudate putamen, nucleus accumbe ns and olfactory tubercle, binding in the entopeduncular nucleus was e nhanced after fluphenazine treatment. Competition studies indicated th at the region-dependent changes in [I-125]SCH-23982 binding after flup henazine exposure were not due to differences in the affinity of fluph enazine or other dopamine ligands for D-1-binding sites. These data su ggest that in addition to modulating striatal function, classical neur oleptics may also alter neurotransmission in the basal ganglia by enha ncing dopamine receptor binding in the entopeduncular nucleus.