Pubdate: Wed, 15 Sep 1999 Source: Reuters Copyright: 1999 Reuters Limited. Author: Clar Ni Chonghaile SCIENCE SLOTS PIECE IN COCAINE ADDICTION PUZZLE LONDON (Reuters) - U.S. scientists have come a little closer to understanding cocaine addiction, throwing a lifeline to addicts who fear that even if they do kick the habit a relapse is inevitable. Researchers at the Yale University School of Medicine found that repeated use of cocaine triggered the production of a new gene in the brain and that the gene, delta-FosB, stayed in the brain long after cocaine use had stopped. ``A cocaine addict is addicted because of the many changes the drug produces in the brain. Some of these changes persist even after years of abstinence,'' Eric Nestler, professor of psychiatry and neurobiology at Yale, told Reuters. ``Our findings help us understand addiction, so that eventually we can better treat it,'' said Nestler, whose research was published in Wednesday's science journal Nature. Nestler and his team found that chronic users of cocaine had high levels of delta-FosB in one area of the brain. ``What we showed is that when delta-FosB builds up in this particular nerve cell type, then there is an increased sensitivity to cocaine,'' Nestler told Reuters. ``However good cocaine felt before, it feels better now.'' With infrequent users of cocaine, delta-FosB is only produced in small amounts. With addicts, it accumulates to a greater extent and becomes a potent biological factor. Addiction to cocaine, or other drugs, is believed to be partly caused by biological changes. ``There has been the sense that there is perhaps some kind of switching of the brain. We think delta-FosB may be one part of the switch,'' Nestler said. He admits research into cocaine addiction is at a very primitive stage but says understanding the part played by delta-FosB could point the way to improved treatment. Understanding the role of delta-FosB in turning a casual user of cocaine into a chronic addict is a step on the way to understanding the biological processes of addiction. Delta-FosB is also produced in the brain by repeated exposure to substances such as heroin, nicotine, alcohol and PCP or angel dust. Nestler and his team used genetically engineered mice and found the animal's responsiveness to cocaine rose dramatically when the delta-FosB gene was turned on in brain regions important for the formation of addiction. But the role of delta-FosB is just one piece in the puzzle that is cocaine addiction. ``We know of other genes that do the same thing in different parts of the brain,'' Nestler said. Nestler said one day it might be possible to neutralize the more persistent neurobiological changes associated with drug addiction. - --- MAP posted-by: Don Beck