The distribution of dopamine D₁ receptors has been determined in post mortem human brain tissues using in vitro receptor autoradiography, with ([³H]N-methyl) SCH 23390 as ligand. The highest densities of dopamine D₁ sites were seen in the nucleus caudates, putamen, globus pallidus pars medialis and substantia nigra. Intermediate densities were associated with the amygdala, mammillary bodies, cerebral cortex and CA1. The remaining part of the hippocampus as well as the diencephalon, brainstem and cerebellum contained low levels of [³H]SCH 23390 binding sites. The distribution of D₁ receptors in the human brain closely resembles that reported for the rat brain. In addition, there was a good correlation between the anatomical localization of D₁ sites and the distribution of dopaminergic nerve terminals in the central nervous system.

The densities of D₁ receptors in the human brain were observed to markedly decrease with age during the first decades of life. However, no further modifications were found beyond the age of 40 years. We did not observe any significant influence of other parameters such as gender and post mortem delay in our samples.