Neuroleptic drugs and their action on different neuronal pathways.

The occurrence of tardive dyskinesia has been related to treatment with most typical neuroleptic drugs. It has been hypothesized that risk of the disorder may be less with some atypical antipsychotic agents. Other contributing risk factors may include an underlying vulnerability of the nervous system. Understanding of these features of tardive dyskinesia should be enhanced through more information on functional differences between dopamine receptors and on how different types of antipsychotic drugs affect such receptors. In our animal studies, we have found evidence that dopamine D-1 and D-2 receptors are functionally linked to different behavioral phenomena in the rat, that they are differently affected by dopamine agonist and antagonist drugs, and that they may be selectively localized to different postsynaptic neuronal systems. We suggest that the development of antipsychotic drugs with a low risk of inducing tardive dyskinesia or of novel treatments for this condition may arise from improved understanding of the functions of various dopamine receptors in the brain.