Studies comparing adolescent and adult rats have added to the evidence that the adolescent brain is particularly vulnerable to nicotine addiction. Dr. Edward D. Levin and colleagues at the Duke University Medical Center allowed male rats not previously exposed to nicotine to self-administer the drug for 4 weeks. During the first 2 weeks, the 13 adolescent rats took more than three times as much nicotine as the 13 adults. Nicotine consumption decreased as the adolescents matured, and it reached adultlike levels by the end of week 4.
In a prior study with female rats, the researchers found that adolescents self-administered twice as much nicotine as adults. Unlike the male rats in the current study, however, as the adolescent female rats matured, they continued to self-administer more nicotine than adults. Taken together, the team's results suggest that adolescent male rats may initially be more sensitive than females to nicotine, but females may experience a more persistent vulnerability.
Neurotoxicology and Teratology 29(4):458-465, 2007. [Abstract]