Dopamine D1 receptor expression in human basal ganglia and changes in Parkinson's disease

The expression of the human dopamine D-1 receptor was examined by reverse transcription polymerase chain reaction (RT-PCR) and radioligand binding using [H-3]-SCH23390 in post-mortem brain tissue that was obtained from normal subjects and patients dying with Parkinson's disease who were receiving treatment with dopaminergic drugs. D-1 receptor mRNA and specific [H-3]-SCH23390 binding sites were found in both striatal (nucleus accumbens, caudate nucleus and putamen) and extrastriatal (globus pallidus and substantia nigra) brain regions. In parkinsonian brain, D-1 receptor mRNA was increased in the nucleus accumbens, while a decrease was detected in the substantia nigra pars compacta. No change in D-1 mRNA levels was found in the other brain areas examined. An increase in the density of specific [H-3]-SCH23390 binding sites was found in the anterior putamen and a decrease in the external segment of the globus pallidus, no changes were detected elsewhere. This study demonstrates that regulation of D-1 receptor expression in the brain of patients dying with Parkinson's disease that were treated with L-DOPA is confined to small alterations in restricted brain regions. (C) 2001 Elsevier Science B.V. All rights reserved.