Cocaine Spurs Long-Term Change in Brain Chemistry

Study in mice finds drug alters gene activity, points to new methods for treatment

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THURSDAY, May 14 (HealthDay News) Many remember those fried-egg "this is your brain on drugs" public service announcements. Now, a new study offers insight into how addictive drugs such as cocaine "cook" the brain.

"The study's findings enable us to glimpse for the first time exactly how cocaine modifies the activity of genes in regions of the brain that that mediate reward," explained Nora Volkow, the director of the U.S. National Institute on Drug Abuse, the organization that supported the study. "These genes represent promising new targets for the development of medications to treat cocaine addiction," she said.

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Scientists led by Dr. Eric Nestler, of New York's Mount Sinai School of Medicine, used a new molecular analysis technique to watch changes in the gene activity of mice that were injected with cocaine. The changes involve a shift in proteins called histones and transcription factors, which bind to DNA and regulate how the genetic information in a DNA strand is read to make a complementary sequence of RNA. A cell uses the information in the RNA to make final protein products.

Using these genetic markers, scientists mapped the effects of drug use in a critical part of the brain's "reward circuitry."

The process showed, for the first time, that a family of genes called the sirtuins are activated by chronic cocaine use and fuel addiction-related behaviors in lab animals.

The research was published May 14 in the journal Neuron.

"This analysis provides fundamentally new information about the range of genes that are altered by cocaine in this brain region," Nestler said. "We showed that blocking the activity of the sirtuins reduced both cocaine's rewarding effects and the motivation to self-administer the drug."

In other words, scientists may someday be able to take away the desire for cocaine as well as the pleasure a person gets from using it, the researchers said.

More information

The U.S. National Institute on Drug Abuse has more on cocaine.

-- Dennis Thompson