By Emma Patten-Hitt

ATLANTA, Mar 09 (Reuters Health) - A recovering cocaine addict can be tempted to use the drug again at the sight or smell of an environment where they once used cocaine. Now researchers have tested a drug in rats that appears to block this "reward pathway" responsible for the craving--and which may help prevent cocaine addicts from relapsing.

"Triggers activate the brain's reward pathway, which often cause relapse to drug-seeking behavior," study author Dr. Madina R. Gerasimov, from the Brookhaven National Laboratory in Upton, New York, told Reuters Health. "In this study, we demonstrated that we can effectively prevent the reward pathway in the brain from responding to an environmental 'trigger,'" she said.

Gerasimov's team tested the drug called gamma-vinyl GABA (GVG) in rats trained to associate a specific environment with cocaine. In the absence of cocaine, the environmental cue stimulated the brain's reward pathway, increasing amounts of the brain chemical dopamine. But when animals were given GVG before being exposed to the environmental cue, no activation of the reward pathway occurred.

According to the researchers, GVG blocks the activity of a receptor found in brain cells and stops the production of dopamine, which is responsible for stimulating the reward pathway that leads to the craving. The findings are published in the March 7th issue of the European Journal of Pharmacology.

Gerasimov noted that researchers have previously demonstrated that GVG effectively blocks the effects of a variety of addictive drugs and decreases cocaine self-administration behavior in rats.

The drug GVG is marketed under the trade name vigabatrin (Sabril), but is currently not approved for use in the US, although it is used for the treatment of epilepsy in children in more than 65 other countries.

"It is novel and exciting to prove that this drug counteracts the measurable changes in the reward pathway presumably underlying relapse," Gerasimov said. "We hope that this important information concerning the mechanism of action of GVG will help to speed up the process of bringing this drug to the market," she told Reuters Health.

"For recovering addicts, this means treatment with GVG may lead to easier recoveries without some of the pitfalls that environmental triggers present," she added.

Related MEDLINEplus Pages:

• Cocaine Abuse