Absence of detectable striatal dopamine D4 receptors in drug-treated schizophrenia.

The difference between saturable binding of [3H]emonapride (to D2, D3 and D4 receptors) and [125I]epidepride (to D2 and D3 receptors) was used to determine dopamine D4 receptors in putamen taken post-mortem from antipsychotic-treated schizophrenic subjects and matched controls. Despite an overall increase in D2/D3 receptor density in schizophrenia, reflecting prior antipsychotic drug treatment, striatal D4 receptors were not significantly detectable in either controls or schizophrenic subjects.