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.
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MAP posted-by: Beth