Cigarette smoke exposure during adolescence but not adulthood induces anxiety-like behavior and locomotor stimulation in rats during withdrawal

Abstract

Adolescence is a critical period for cigarette smoking. Studies have shown that adolescent smokers are more likely to become addicted, are less likely to quit, and are more prone to relapse. In the present study, we examined the affective symptoms experienced by adolescents during withdrawal from cigarette smoke exposure. Towards this goal, adolescent male rats were repeatedly exposed to cigarette smoke, through an automated smoking machine, for 14 days. Then, cigarette smoke exposure was discontinued to induce spontaneous withdrawal. During the withdrawal period, anxiety-like behavior (elevated plus-maze test), locomotor activity (open-field test), and learning and memory (passive-avoidance test) were evaluated. These behavioral evaluations were conducted during the first, third, seventh, and fourteenth day of withdrawal. For comparison, parallel experiments were performed in adult rats. We found that adolescent rats exposed to cigarette smoke experiences increased anxiety-like behavior and locomotor activity during withdrawal relative to control rats. Learning and memory processes were undisturbed. On the other hand, adult rats exposed to cigarette smoke did not show any statistically significant behavioral alteration during withdrawal. These results are consistent with the notion that adolescents are differentially sensitive to the withdrawal effects of cigarette smoking. This sensitivity might be a factor why adolescent smokers have difficulty quitting and are more prone to relapse.