Cigarette Smoke Exposure Greatly Increases Alcohol Consumption in Adolescent C57BL/6 Mice
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Reprint requests: William R. Proctor, PhD, Department of Psychiatry, University of Colorado School of Medicine, Mail Stop 8344, 12800 E. 19th Ave., Room 8101, Aurora, CO 80045; Tel.: 303-724-4151; Fax: 303-724-4425; E-mail: email@example.com
Alcohol and tobacco are often used together, and alcoholism is much more common among smokers compared with nonsmokers. Studies in humans suggest that nicotine (an active ingredient in cigarette smoke) can increase the consumption of alcohol. Research on rats and mice demonstrated mixed results; some studies report that nicotine increases alcohol consumption, while others show a decrease in drinking. Because cigarette smoke includes many other chemicals, these also may play a significant role in alcohol consumption. For example, 2 of these other constituents, monoamine oxidase inhibitors and acetaldehyde, increase alcohol tolerance and/or alcohol consumption in rodents. This study was designed to investigate how cigarette smoke from tobacco may modify self-administration of alcohol in adolescent C57BL/6 mice, a critical time when adolescent humans begin abusing drugs.
C57BL/6 male mice (4 to 5 weeks old) were acclimated for 3 weeks to consume a 10% (w/v) alcohol solution during a 2-hour daily access in the dark. Subsequently, half the animals were exposed to cigarette smoke for 6 h/d for 16 days. The remaining animals (control) were placed in a smoke-free adjacent chamber. Immediately following the 6-hour period in the chambers, the control and smoke-exposed mice were given access to the 10% alcohol solution for 2 hours.
Animals exposed to cigarette smoke for 6 h/d consumed approximately 3- to 5-fold more alcohol than the mice in the control group throughout the 16-day study. The mice in the smoke group had a blood alcohol concentration that was nearly 4-fold that of the control mice.
Cigarette smoke increases alcohol consumption several fold higher than reported studies using nicotine treatment alone in adolescent rodents. Thus, this model should be useful to determine the roles of other bioactive components in cigarette smoke that may be important in the high co-abuse of smoking and alcohol consumption.