Loss of dopamine uptake sites and dopamine D-2 receptors in striatonigral degeneration

To explore the mechanisms underlying L-dopa response, we studied, by postmo rtem autoradiography, selective makers of dopamine presynaptic terminals, [ H-3]WIN 35428, and dopamine D-2 receptors, [H-3]nemonapride, in the putamen of four Parkinson's disease (PD) and one striatonigral degeneration (SND) neuropathologically confirmed brains as compared with six matched control b rains. Dopamine uptake transporter was dramatically decreased (>90%) both i n PD and SND striatum. Dopamine D-2 receptors were preserved in PD, but cle arly reduced (> 6%) in the SND putamen. These data confirm that L-dopa resp onse is closely associated with the preservation of striatal dopamine D-2 r eceptors, (C) 2000 Elsevier Science B.V. All rights reserved.