DENVER - A drug that Duke University Medical Center researchers have successfully used to help some people quit smoking may also help curb cocaine cravings, according to studies conducted in rats.

The drug mecamylamine, used in combination with nicotine to help reduce the urge to smoke cigarettes, has now been shown in animal studies to reduce their self-administration of cocaine.

Rats that were trained to press a lever in order to get cocaine no longer pressed it with the same frequency after they were given mecamylamine, said Edward Levin, lead author of the study. Results were prepared for presentation Saturday by Tonya Mead and Amir Rezvani at the International Behavioral Neuroscience Society meeting.

When injected with mecamylamine, the mice infused cocaine 11 times per hour, versus 19 times per hour when they received a placebo injection of saline -- a reduction of more than 40 percent.

"It's always very exciting when a drug used for one addiction has implications for a broader range of addictive drugs," said Levin, whose study was funded by the National Institutes of Health.

Mecamylamine is an older medication originally used to treat high blood pressure. Researchers now know it blocks some of nicotine's ability, and potentially that of other drugs, to generate feelings of pleasure in the brain.

Levin said it works by occupying specific sites, called "nicotinic receptors," on nerve cells where nicotine would normally act. When mecamylamine blocks these receptors, nicotine can no longer exert its full action, that of stimulating the release of dopamine.

Dopamine is the primary brain chemical involved in generating pleasure. Drugs like nicotine, alcohol and cocaine all increase available amounts of dopamine and thereby increase the pleasure sensation, said Jed Rose, chief of the Nicotine Research Program at Duke and study co-author. Eventually, the brain may prefer the drug over natura
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Contact: Renee Twombly
Twomb001@mc.duke.edu
919-684-4148
Duke University Medical Center
7-Apr-2000