A gene found to be key to schizophrenia medication will trigger ``an avalanche of research'' that could improve treatment for psychosis, Parkinson's disease and other brain ailments, a scientist says. Scientists worldwide ``have really been poised to take advantage of this development,'' which could provide insights into the body's potential role in mental illness, said Kenneth L. Davis, chairman of the psychiatry department at the Mount Sinai School of Medicine in New York. The results could include improved treatments for diseases that include psychosis, which is a loss of touch with reality seen in schizophrenia and sometimes in depression, manic-depression and other disorders, he said. It also could lead to better treatment of Parkinson's disease, which is often characterized by tremors and rigidity, Huntington's disease, which hinders movement and intellectual abilities, and Tourette syndrome, which includes jerky movements and vocal mannerisms, Davis and other researchers said. Davis was responding to a report in today's issue of the British journal Nature. In the article, researchers said they had isolated the gene that acts as a blueprint for a protein called the D-2 dopamine receptor, which is made by brain cells. The receptor, which sits on the surface of the cells, is where anti-psychosis drugs exert their effects on the brain. Normally, the receptor's role is to respond when adjacent brain cells secrete a substance called dopamine, allowing brain cells to communicate. The defining of one receptor in the past has led to discovery of a related family of them, Davis said. If a family of dopamine receptors is found, scientists may be able to design drugs that affect only the receptors linked to disease and avoid side effects of current medications, he said. Side effects of current anti-psychosis medications, for example, include tardive dyskinesia, a syndrome of involuntary movements of the mouth, tongue, limbs or trunk. In the study, researchers said they identified the receptor gene in rats, defined its chemical makeup and made functioning copies of it. Since then, they also have isolated and partially defined the human receptor gene, Olivier Civelli said in a telephone interview. The researcher reports the work in Nature with James Bunzow and others at the Oregon Health Sciences University in Portland, and with researchers at the Veterans Administration Medical Center in Portland and the Oregon Regional Primate Center in Beaverton. Other scientists called the discovery an important boost for research into the dopamine receptor. Davis predicted ``an avalanche of research'' by investigators. ``We've all been waiting for it,'' he said. ``This is an important and essentially fundamental step'' in helping scientists understand how anti-psychotic drugs work, ``and thereby indirectly understand what may be the biological mechanism underlying psychotic disorders.'' Scientists also may be able to learn about the mechanisms that turn the receptor gene on and off, which may shed light on schizophrenia, he said. In addition, focusing on the receptor gene may help scientists study the inheritance of a tendency toward schizophrenia and perhaps other diseases, said Arnold Friedhoff, psychiatry professor at the New York University Medical Center. That in turn could lead to better matching of patients to proper medications, he said. He said other follow-up studies could help scientists understand the overall dopamine communication network among brain cells, which is ``undoubtedly going to provide extremely important new insights into its role ... in regulating mental processes.'' Since it is the target of drugs that ease psychosis caused by a wide range of conditions, it ``must have a regulatory role in keeping things on track,'' he said. ``The more we understand about its function, the more likely it is we'll be able to not only treat mental illness, but in the long run prevent it,'' Friedhoff said.
