Pubdate: Thu, 03 Apr 2003 Source: Times-Picayune, The (LA) Copyright: 2003 The Times-Picayune Contact: http://www.nola.com/t-p/ Details: http://www.mapinc.org/media/848 Author: Newhouse News Service MID-BRAIN MAY CONTAIN ADDICTION LINK Addiction to alcohol may be driven in part by a previously unknown brain signaling pathway discovered by researchers at Oregon Health & Science University. Researchers said the system of brain cells and signaling molecules appears to act separately from the better-known dopamine reward system, which has been the focus of addiction research for years. "It seems to be an independent system," said study co-author Andrey Ryabinin, an assistant professor of behavioral neuroscience at OHSU. The study was published recently in the Journal of Neuroscience. The findings point the way to unexplored territory for seeking new alcoholism treatments using drugs that block or modify the signaling pathway to reduce addictive cravings. Ryabinin and colleagues made use of a peculiar family of laboratory mice, known for a strong lust for alcohol. After allowing the mice a final drinking binge, the researchers dissected their brains to study how the pattern of gene expression might differ from other mice -- an inbred strain with little taste for alcohol. The experiments led researchers to a cluster of brain cells, called the Edinger-Westphal nucleus, in the midbrain. The structure exists in human brains, where its best-known job is the subconscious control of the eyes' pupil size. But in the drink-loving mice, the cluster of brain cells kicks into high gear after alcohol consumption. These brain cells produce a compound called urocortin, originally discovered in 1995. What it does remains uncertain. Scientists at the Salk Institute for Biological Studies gained a broad patent on urocortin in 2001, claiming uses in controlling blood pressure, decreasing inflammation, improving memory and elevating mood. In the mouse experiments, Ryabinin and collaborators at Indiana University found that urocortin signaling may be crucial to the animals' alcohol seeking. Mice that consume large quantities of alcohol have high levels of urocortin in their brains. Teetotalers have low urocortin levels. The association held true in other strains of mice, and in the offspring of imbibers mated to teetotalers. "That is very compelling evidence, I think, to suggest that this may actually be a neurochemical pathway involved in alcohol consumption," said Todd Thiele, an assistant professor of psychology at the University of North Carolina, who was not involved in the study. But Thiele said much additional work needs to be done to nail down that conclusion. He would like to see the findings repeated in other reliable animal models of addiction, such as rats. - --- MAP posted-by: Beth