Characterization of dopamine receptor binding sites in the subthalamic nucleus.

Experiments were undertaken to determine the distribution and binding profile of dopamine (DA) receptors within a key extra-striatal region of the rat basal ganglia, the subthalamic nucleus (STh). Analysis of [125I]NCQ-298 autoradiograms showed that binding sites of the D2-receptor family are abundant in the STh. Competition studies indicated that these sites were specifically of the D2 subtype. However, contrary to previously published data, [125I]SCH-23982 autoradiograms failed to reveal D1 receptor binding in the STh. These data suggest that DA acting at D2 receptors may directly modulate STh neural activity and furthermore that the antagonism of STh D2 receptor binding by neuroleptics may be involved in the expression of extrapyramidal motor disturbances.