By manipulating receptors in the brains of rats, researchers were able to control whether the first exposure to nicotine was enjoyable or repulsive. They experimented on two types of receptors for dopamine, a chemical messenger in the brain’s reward circuitry.
By blocking the receptors, the researchers were able to switch how nicotine was processed — from repulsive to rewarding or positive. The natural variations that occur between people may therefore explain why some are more likely to become addicted to nicotine.
CBC News August 5, 2008
The Journal of Neuroscience, August 6, 2008, 28(32):8025-8033