Pubdate: Sat, 06 Mar 1999 Source: Arizona Republic (AZ) Contact: http://www.azcentral.com/news/ Forum: http://www.azcentral.com/pni-bin/WebX?azc Copyright: 1999, The Arizona Republic. DOPAMINE NOT SECRET TO ADDICTION, STUDY SAYS Dopamine may not be the brain's "feel-good" chemical after all, a study found, suggesting that scientists trying to unlock the secrets of drug addiction may have been off target for the past two decades. The naturally produced brain chemical, rather than being the key player in the pleasure process, is only a messenger and one of several factors, according to the study, published Thursday in the journal Nature. "It certainly says the picture is much more complicated than being just dopamine alone, and it will lead to the search for other chemical substances in the brain," said the study's author, chemist R. Mark Wightman of the University of North Carolina-Chapel Hill. Dopamine, discovered in 1957, came into prominence in the early 1960s when scientists discovered that several antipsychotic drugs targeted it. In the late 1970s, researchers found that cocaine, heroin and other addictive drugs increase levels of dopamine in the body. Since then, some scientists have tried to develop a medication that would cure cocaine addiction by blocking dopamine. The latest study is another in a series that cast doubt on that approach. Dopamine appears to be related to "novelty, predictability or some other aspect of the reward process, rather than to hedonism itself," the researchers reported. What chemical or process is ultimately responsible for the pleasure is "not really clear right now." - --- MAP posted-by: Rich O'Grady