Vaccine stops nicotine from reaching the brain, may prevent addiction

Posted: June 28, 2012 at 8:13 am

(CBS News) Trying to quit smoking? It's tough - studies suggest 70 to 80 percent of people who try to quit smoke within six months.

That's because nicotine is so addictive, says Dr. Ronald G. Crystal, chairman and professor of Genetic Medicine at Weill Cornell Medical College in New York City. Crystal's team has announced they've successfully tested a new vaccine that may treat nicotine addiction.

Crystal told HealthPop that many stop-smoking campaigns try to attack the source of smoking, cigarettes, but what his team wanted to do was find a way to block the sensation nicotine provides in the brain that makes smoking so addictive.

"Smoking is a terrible problem in society," Crystal told HealthPop. "It's enormously costly to our society, not only the pain and suffering, but the amount of health care costs. In that sense, it's important for us to develop strategies that in fact will be effective."

His team's vaccine is described in the June 27 issue of Science Translational Medicine. How does it work?

Much like vaccines for diseases that create antibodies to fight infection, the vaccine creates antibodies against nicotine. However, previous attempts at similar vaccines have failed because within a few weeks the antibodies are gone, which won't exactly help people stay smoke-free.

Crystal's team developed a vaccine that contains a virus consisting of a genetic sequence they engineered from a nicotine antibody, and injected it into the liver of mice. The injection genetically modifies the liver to churn out nicotine antibodies, along with other cells it typically makes, thus providing a nicotine antibody "factory" in the body. That suggests the effect won't diminish over time like that of other antibodies. The antibodies then work by targeting the nicotine cells within seconds of exposure and preventing them from reaching receptors in the brain that provide the "chill out" feeling, as Crystal called it.

"The antibodies are little Pac-men that like nicotine and just gobble it up," Crystal said.

When mice are given nicotine, they experience reduced blood pressure and heart activity and appear "chilled out," which suggests the nicotine reached their brains. But mice tested with the new vaccine appeared just as active as they were before, as measured by infrared beams in their cages.

"It's like giving them water - nothing happens," Crystal said. However he added that there was a caveat to his study: "Mice aren't small humans."

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Vaccine stops nicotine from reaching the brain, may prevent addiction

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