By manipulating receptors in the brains of rats, the researchers were able to control whether the first exposure to nicotine was enjoyable or repulsive. The study appears in the Aug. 6 issue of the Journal of Neuroscience.
"During the early phase of tobacco exposure, many individuals find nicotine highly unpleasant and aversive, whereas others may become rapidly dependent on nicotine and find it highly rewarding," said Steven Laviolette, a professor of anatomy and cell biology at the University of Western Ontario.
"We wanted to explore that difference," he added in a release.
The team 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 explain why some are more likely to become addicted to nicotine.
"Importantly, our findings may explain an individual's vulnerability to nicotine addiction, and may point to new pharmacological treatments for the prevention of it, and the treatment of nicotine withdrawal," said Laviolette.
For example, the researchers were able to reduce withdrawal symptoms in the rats studied.
The research was funded by the Canadian Institutes of Health Research and the Canadian Psychiatric Research Foundation.
Canada is considered to be among those countries at the forefront of anti-smoking legislation.
Smoking has been banned from most offices for some time, but the bans have now extended to bars, restaurants and other public places. Some cities have banned indoor smoking outright, shutting down separate smoking rooms altogether.