Differential visualization of dopamine D2 and D3 receptors in rat brain.

The mRNA for the dopamine D3 receptor is confined to limbic regions and the D3 receptor may be a target for antipsychotic medications. We used quinpirole and domperidone to try to visualize D3 and dopamine D2 receptors selectively in rat brain, using in vitro autoradiography and digital subtraction. We used 125I-sulpiride, a ligand with high affinity for the D2 receptor in brain and for the D3 and D2 receptors in transfected cells. Our data indicate that the D2 receptor is present in much greater density than the D3 receptor in rat brain, even in limbic regions.