Study: Cocaine keeps pleasure center 'on'

Jan. 7, 2010 at 8:25 PM   |   Comments

WASHINGTON, Jan. 7 (UPI) -- Chronic cocaine addiction keeps a brain enzyme from shutting off pleasure-circuit genes, thus making the addiction worse, U.S. researchers said Thursday.

The finding could lead to improved treatments for addictions, Mount Sinai School of Medicine researchers said in a study published in the journal Science.

The study, funded by the National Institute on Drug Abuse, part of the U.S. government's National Institutes of Health, found that cocaine is so addictive because it represses gene 9A, which makes an enzyme that plays a critical role in switching genes on and off.

With G9A repressed, or "off," the pleasure circuit remains "on" and cravings for cocaine increase dramatically, the researchers found.

But by reversing the G9A repression, the cocaine cravings noticeably decreased, the researchers said.

"This fundamental discovery advances our understanding of how cocaine addiction works," NIDA Director Nora Volkow said. "Although more research will be required, these findings have identified a key new player in the molecular cascade triggered by repeated cocaine exposure, and thus a potential novel target for the development of addiction medications."

The researchers carried out their study on mice, giving one group of mice repeated doses of cocaine and another group repeated doses of saline with a final dose of cocaine. The researchers wanted to see how the effects of chronic cocaine exposure differed from one-time exposure.

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