Update on dopamine receptors.

This paper reviews recent developments in dopamine receptor biology, with an emphasis on our recent understanding of the anatomical locations of where various genes for the dopamine receptors are expressed. At least five genes encoding dopamine receptors have been discovered. These five receptors have distinct pharmacological profiles as well as unique neuroanatomical distributions. While D1 and D2 receptors are widely expressed in many neural systems, the novel D3 and D4 receptors appear to be concentrated within parts of the limbic system, and the D5 receptor has a limited and unusual distribution. The distinct distributions of each of the dopamine receptors in brain facilitates a new understanding of potential neurochemical and neuroanatomical substrates of psychiatric illnesses such as schizophrenia, permits an understanding of observed actions and side effects of psychotropic agents, and provides clues for the rational development of new drugs with effects in the dopaminergic system.