The changes of the histamine H3 and dopamine D1 or D2 receptor binding sites induced by quinolinic acid treatment were studied in order to discriminate the comparative distribution. This treatment resulted in similar decreases in histamine H3 and dopamine D1 receptor binding sites in the striatum and ipsilateral substantia nigra. Dopamine D2 receptor binding sites were relatively well conserved, whereas H3 receptors decreased considerably. These results suggest that histamine H3 and dopamine D1 receptor binding sites are localized on the striatonigral projection neurones which are together sensitive to quinolinic acid, and that the distributional compartment of dopamine D2 receptor binding sites is quite different from those of histamine H3 and dopamine D1 receptors.