Nicotine Differentially Modulates Emotional-Locomotor Interactions for Adult or Adolescent Rats

Abstract

Previous research has shown that exposure to nicotine and other drugs of abuse stimulate dopaminergic neurons in the mesolimbic circuit. Sustained activation of this circuit by prolonged exposure to drugs promotes locomotor sensitization. However, there are inconsistent reports about nicotine-induced locomotor sensitization when assessed among different developmental stages. We evaluated exploratory behavior on specific areas of the open field as an indicator of behavioral disinhibition and general locomotor activity as an indicator of nicotine-induced locomotor sensitization, to further explore the mechanisms underlying behavioral adaptations to nicotine exposure in animals from different developmental stages. We found that while adolescent and adult rats are equally responsive to nicotine-induced locomotor sensitization, nicotine disrupts inhibition of risk-related behavior only in adolescent rats. Together, our results suggest that chronic daily exposure to nicotine promotes potentiation of its stimulant effects on locomotor activity. In adolescents, this effect is accompanied by a decreased capacity to inhibit risk-related behaviors under the acute effect of the drug.