Dopamine D3 receptor: basic and clinical aspects.

The recently discovered dopamine D3 receptor can be considered as a D2-like receptor: it is encoded by a gene comprising several introns; it is both an autoreceptor and a postsynaptic receptor, well recognized by antipsychotics. It differs, however, from the D2 receptor by a much more discrete expression, mostly in few limbic brain areas, e.g. shell of nucleus accumbens, islands of Calleja, and a considerably higher affinity for dopamine. Two association studies preliminarily suggest that the homozygotes for a D3 receptor gene polymorphism display twofold higher risk of schizophrenia, whereas several linkage studies led to inconclusive results.