Chronic continuous nicotine exposure during periadolescence does not increase ethanol intake during adulthood in rats.
BACKGROUND
Nicotine has been considered as the gateway drug, because many teenagers experience cigarette smoking before seeking out other drugs. By using an animal model system, we assessed the effects of chronic continuous nicotine exposure during periadolescence on ethanol intake during young adulthood.


METHODS
Periadolescent Sprague-Dawley rats (35 days old) were used at the beginning of this study. These animals received subcutaneous implantation of nicotine pellets (15 or 25 mg in 21-day time-release pellets) or placebo pellets (0 mg of nicotine) on postnatal day 35. Beginning on postnatal day 53, the animals received various concentrations of ethanol solution during their active period (5:00 PM to 9:00 AM) starting with 2% (v/v, 4 days), then 5% (5 days), 8% (6 days), and 10% (6 days). Between 9:00 AM and 5:00 PM of the same day, the ethanol solution was replaced by regular tap water. The amounts of ethanol solution and regular water were measured daily.


RESULTS
The analyses showed that ethanol intake (grams per kilogram of body weight) in the nicotine 15 and 25 mg groups did not differ from that in the nicotine 0 mg group, and no sex difference was found in ethanol intake. However, ethanol intake was increased as a function of the treatment days.


CONCLUSIONS
The results showed that chronic continuous nicotine exposure during adolescence did not increase ethanol intake in rats during young adulthood.