Dopamine uptake sites and dopamine receptors in Parkinson's disease and schizophrenia.

Dopamine uptake sites, labelled by 3 nM [3H]GBR 12935, were reduced by 28-34% in post-mortem Parkinson's diseased striata (n = 22) compared to control striata (n = 28). There was no significant difference between post-mortem striata from schizophrenics (n = 16) and controls. Both dopamine D1 and D2 receptors are consistently elevated in Parkinson's diseased striata from patients who have not been medicated with L-dopa pre-mortem. Both these receptors are down-regulated by L-dopa pre-mortem. In schizophrenia, however, while the density of D1 receptors is similar to control, the D2 receptors are consistently elevated.