Differential effects of pair housing on voluntary nicotine consumption: a comparison between male and female adolescent rats

Rationale Tobacco smoking occurs in a wide array of social circumstances. Social support for quitting is generally used to stop smoking, while peer interactions may be a crucial factor in triggering tobacco use among adolescents. Objectives To determine the role of social factors on nicotine dependence, we compared single- and pair-housed rats subjected to voluntary oral nicotine consumption tests. Methods Six-week-old adolescent rats were subjected to experimental procedures and assigned to one of the following groups: a male single group, a male pair group with a sibling, a female single group, and a female pair group with a sibling. To measure voluntary nicotine intake, we adopted a two-bottle free-choice paradigm for each two days using 25 mu g/ml and 100 mu g/ml nicotine solution. Results There were no differences in change in body weight or food intake between the two groups of either sex. Pair-housed female rats showed a reduction in nicotine consumption and preference for both low- and high-dose nicotine solution, while pair-housed male rats showed only reduced consumption and preference for high-dose nicotine solution, but not low-dose solution, as compared to single-housed male rats. Conclusions Nicotine consumption is sex-dependently controlled by the social circumstances of rats. This study broadens our perspectives on the role of social interactions as a therapeutic strategy to treat nicotine addiction-related behaviors depending on sex.