DISTRIBUTION OF D-1-DOPAMINE AND D-2-DOPAMINE RECEPTORS, AND DOPAMINE AND ITS METABOLITES IN THE HUMAN BRAIN

Densities and distribution of D-1-dopamine and D-2-dopamine receptors were investigated in vitro using [H-3]SCH 23390 and [H-3]raclopride in receptor binding assays and autoradiography on human post mortem whole hemisphere slices to serve as anatomical correlates to PET studies using [C-11]SCH 23390 and [C-11]raclopride. In addition, the levels of dopamine and its metabolites were determined by HPLC in various brain regions. Both dopamine receptor subtypes, as well as dopamine, HVA and DOPAC, were primarily found in the basal ganglia. Very high densities of D-1-dopamine receptors were found particularly in the medial caudate nucleus, whereas D-2-dopamine receptors were evenly distributed throughout the caudate. The densities of D-1- and D-2-dopamine receptors were similar in the caudate nucleus and the putamen, whereas there were 4 to 7 times higher densities of the D-1- than of the D-2-dopamine receptors in several limbic and neocortical regions. The receptor distribution in the autoradiographic study was consistent with that demonstrated in the living human brain using [C-11]SCH 23390 and [C-11]raclopride.