How are the various dopamine receptors involved in the pathophysiology and treatment of schizophrenia?
At the moment there are five different dopamine receptors. Nobody knows quite what the roles of the first, third, fourth, and fifth receptors are. However, there are strong clues, both clinical and basic. D1 is cooperative with D2 even though signs and symptoms of the psychosis primarily come from D2. The exact mechanism and clinical benefit of D1 is unclear; however, it appears that D1 is cooperative and helpful to D2 but not involved directly in the psychotic process. In the case of Parkinson’s disease, patients are alleviated by L-dopa because it stimulates both D1 and D2, and provides a smoother alleviation of the Parkinson’s disease akinesia. The patients can walk better and move better if both D1 and D2 are stimulated. It is unclear what role D3 has in the brain and body. The clinical trials on a compound called BP-897, a D3 blocker, at 10 mg/day, did not alleviate the signs and symptoms of psychosis.3 Therefore, although it is unlikely that D3 is an antipsychotic, this research
