The Dopamine D3 Receptor and Its Implication in Neuropsychiatry Disorders and Their Treatments

The pleiotropic actions of dopamine, as well as of drugs used in the treatment of Parkinson’s disease and schizophrenia, have long been assumed to result from interaction with only two dopamine receptors termed D1 and D2. In spite of previous suggestions of additional dopamine receptors, the discovery of the D3 receptor (Sokoloff et al. 1990) was rather unexpected, as were those of the D4 and D5 receptors that followed (Sunahara et al. 1991; Van Tol et al. 1991). From the beginning, attention has been attracted by the restricted distribution of the D3 receptor in the brain, seemingly related to functions of dopamine associated with the limbic brain. Nevertheless, the initial lack of evidence of functional coupling of this receptor, as well as of selective pharmacological tools to investigate its functions, raised questions about its physiological significance.