Study: Cocaine Scrambles Genes' Behavior in the Brain's Pleasure Center

By Andrew Moseman | January 11, 2010 2:01 pm

cocaineAddiction researchers constantly wade through the ways that drugs like cocaine change your brain, and a new study in Science has pointed to a new epigenetic factor. Cocaine, the researchers say, can scramble the way genes turn on and off in a key brain region associated with pleasure and reward.

Ian Maze said his team gave one group of mice repeated doses of cocaine and other group repeated doses of saline with just one blast of cocaine at the end to study the differences. The team paid particular attention to a protein called G9a, whose behavior in the nucleus accumbens region of the brain seems to be altered by cocaine use. The role of the protein appears to be to shut down genes that shouldn’t be on. One-time use of cocaine increases levels of G9a. But repeated use works the other way, suppressing the protein and reducing its overall control of gene activation [TIME]. The researchers found that the overactive genes caused brain cells in the region to grow more connections to each other. The growth of such neural connections can reflect learning. But in the case of addiction, that may involve learning to connect a place or a person with the desire for more drugs [TIME].

G9a changes in the cocaine-addicted mice were persistent, too. Maze showed that even after a week of abstinence, mice given a new dose of cocaine still had elevated levels of gene activation in the nucleus accumbens, meaning G9a levels were still low…. Maze also showed that when he intervened and raised G9a levels, the mice were less attracted to cocaine [TIME].

Though this was just a rodent study, National Institute on Drug Abuse director Nora Volkow said it could be a crucial piece of the cocaine addiction puzzle. “One of the questions we’ve had all along is, after discontinuing a drug, why do you continue to be addicted? This is one of the mechanisms that probably is responsible for these long-lasting modifications to the way people who are addicted to drugs perceive the world and react to it,” she said [Reuters]. Much more research is necessary, but the research could point the way to the development of addiction medications down the road.

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Image: iStockphoto

CATEGORIZED UNDER: Health & Medicine

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