Nicotine's Brain Actions Linked to Reward Pathways

Nicotine's action in the brain explains why smokers report the first cigarette of the day is the most pleasurable.

Neuroscientists at Baylor College of Medicine studied how the brain reacts to nicotine and reported results in the November 27 issue of the journal Nature.

Dopamine release is related to aspects of reward, Dr. Dani says, so it shapes behaviors by giving a reward or feeling of pleasure in response to external stimuli. Receptors in the midbrain neurons, called nicotinic acetylcholine receptors, respond to nicotine as it enters the body after smoking a cigarette.

"We found that as the nicotine first arrives, the neurons burst with activity," Dr. Dani says. "That burst of activity in the neurons causes dopamine release that contributes to the sensation of pleasure."

The first cigarette of the day gives smokers their first exposure to nicotine in eight to 10 hours, so the neurons experience an extreme burst of activity.

Dr. Dani's group also found that over time some nicotinic receptors stop responding and turn off, or desensitize, even though nicotine is still present. These receptors will not respond again until nicotine is removed and the receptors have time to recover.

- From Baylor College of Medicine

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Courtesy of Texas Medical Center News

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©2006 Texas Medical Center

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