Dopamine receptors and schizophrenia.

202 Introduction Dopamine systems have long been implicated in schizophrenia and its treatment. There is, however, little evidence for a primary abnormality of dopaminergic innervation in the disease, although subtle neuronal deficits, for which there is substantial evidence in the brain in schizophrenia, could conceivably affect dopaminergic neurotransmission in an indirect manner. However, dopamine receptors have attracted much research interest, primarily since the dopamine D2 receptor subtype has long been considered the common site of action of the classical antipsychotic drugs. In addition, there have been reports of abnormalities in the densities of these D2 and D2-like receptors in the brain in schizophrenia, and it is the possible roles of these subtypes of dopamine receptors in the aetiology and treatment of schizophrenia that will be reviewed here.