During 1999–2001, investigators at the Uniformed Services University of Health Sciences, F. Edward Hebert School of Medicine, Bethesda, Md., developed an animal model to study the behavioral and biological effects of nicotine on adolescents and young adults.
The investigators sought to discover whether adolescent animals differ from adults in their sensitivity to nicotine, which they suspected might help explain why young people are vulnerable to tobacco use and nicotine addiction.
The investigators conducted a series of experiments with 83 male and female rats; 42 were adolescents (30 days old) and 41 were adults (60 days old). The rats received nicotine or a saline solution via a small pump implanted underneath their skin.
- Nicotine did not reduce weight or appetite in adolescent female rats, but did so in adult rats and adolescent males. The findings run counter to the popular wisdom of many teen girls, who cite appetite and weight control as a reason for beginning to smoke, the investigators note.
- Adolescent male rats were more sensitive than adult rats or adolescent female rats to nicotine's activity-enhancing effects.
- In the presence of other animals, adolescent male rats were more sensitive to nicotine's activity-enhancing and aggression-reducing effects than were adult rats or adolescent females.
- Nicotine appears to enhance anxiety-related behavior in adult male rats, but decreases it in adolescent males.