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.