Effects of dopaminergic drugs on innate pheromone-mediated reward in female mice: a new case of dopamine-independent "liking."

Abstract

Male sexual pheromones are innately rewarding to adult female mice, but the role of dopamine in this natural reward is unknown. The authors have tackled this issue by assessing the effects of intraperitoneal injections of dopamine D1 (SCH 23390, 0.02- 0.05 mg/kg) and D2 (sulpiride, 20.00 mg/kg) antagonists, a dopamine releasing agent (amphetamine, 0.50 -2.00 mg/kg), and D1 (SKF 38393, 10.00 -20.00 mg/kg) and D2 (quinpirole, 0.20 -1.00 mg/kg) agonists on the chemoinvestigation displayed by female mice in male- versus female-soiled bedding 2-choice tests. Dopamine antagonists and quinpirole failed to affect the unconditioned preference displayed by females towards male chemosignals, whereas both amphetamine and SKF 38393 abolished it. Finally, D1 and D2 antagonists did not block the induction of operant place conditioning by male chemosignals. As the female mice were tested in their first encounter with male sexual pheromones, their behavior can only be influenced by the "liking" component of reward. Therefore, the results suggest that dopamine mediates neither the hedonic properties of male sexual pheromones nor the acquisition of conditioned place preference. However, dopamine acting on D1 receptors might inhibit female mice attraction towards male chemosignals.