Brief exposure to low levels of nicotine, as little as that provided by a single cigarette, can cause lasting changes in the brain's "reward" areas, report two University of Chicago scientists in the August 2000 issue of the journal Neuron. The finding is a major advance in understanding the process of nicotine addiction.

The researchers discovered that nicotine uses a mechanism responsible for learning and memory to enhance the connections between one set of nerve cells that are sensitive to the drug and other nerve cells that register pleasure. They also demonstrate that the first exposure to nicotine can induce an enduring "memory trace," which amplifies the pleasing effects of the drug -- and boosts the desire to repeat the exposure.

By uncovering the precise cellular mechanisms of nicotine's effect, this study suggests new and more precise targets for drugs designed to block this powerful craving.

"This appears to be the crucial first step in the process of addiction," said neurobiologist Daniel McGehee, Ph.D., assistant professor in the department of anesthesia and critical care at the University of Chicago and director of the study. "Now that we know how this happens, we can begin to search for better ways to intervene."

The reinforcing effect of nicotine is the primary reason people cannot quit smoking, despite widespread awareness that smoking causes cancer, heart disease, stroke, emphysema, bronchitis, vascular disease, cataracts, impotence and many other health problems. Nicotine dependence has been esti
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Contact: John Easton
jeaston@uchospitals.edu
773-702-6241
University of Chicago Medical Center
23-Aug-2000