Behavioral Reactivity to Social Defeat Stress after Nicotine Exposure during Adolescence in C57/BL6 Male Mice

Nicotine use during adolescence is associated with the development of many debilitating pathologies in adulthood such as anxiety and depression. Adolescence is a time of many social pressures and biological changes occurring within the brain and body. Therefore, studying the effects of nicotine exposure during adolescence on stress and subsequent sensitivity to nicotine itself is of great interest. To examine these questions I designed experiments to assess both short (i.e., 24 hours after treatment) and long-term (i.e., four weeks after treatment) behavioral consequences of nicotine (0.32 mg/kg) exposure during adolescence (i.e., postnatal days 35-49) in C57/BL6 male mice by exposing them to social-defeat stress, social interaction, and subsequent preference for nicotine. Nicotine-treated mice in the short-term condition displayed avoidant behaviors and a preference for the lowest concentration of nicotine (5 mg/l). Interestingly, the nicotine-treated mice in the long-term condition displayed enhanced social avoidance as well, with a similar preference for the low concentration of nicotine. These results indicate that exposure to nicotine during adolescence influences social interaction behavior and increases preference for nicotine, findings that last into adulthood. Future studies using different stressors and a complete nicotine dose-response may reveal further insight into how nicotine affects this age group and its long-lasting consequences. The work presented here increases our understanding of the effects of nicotine exposure during adolescents and the later effects, which may develop over time.