Dopamine D1 receptor antagonist reduces stimulant-induced conditioned place preferences and dopamine receptor supersensitivity.

ABSTRACT

Repeated administration of stimulants induces conditioned place preference (CPP). Dopamine receptor supersensitivity is developed in stimulant-induced CPP animals; however, dopamine receptor subtypes associated with the development of supersensitivity in CPP animals are largely unknown. The present preclinical study aimed to examine whether dopamine D1 or D2 receptor antagonists exert inhibitory effects on stimulant-induced psychological behaviors. Additionally, the authors aimed to elucidate the role of dopamine receptor supersensitivity on the development of reward-related behavior. Sprague Dawley rats subjected to methamphetamine- and cocaine-induced CPP tests were treated with dopamine D1 (SCH23390) or D2 (sulpiride) receptor antagonists. Following the CPP experiment, rats were challenged with apomorphine (dopamine receptor agonist), and locomotor activity was measured. Methamphetamine- and cocaine-induced CPP was reduced with the administration of SCH23390, but not sulpiride. In addition, the apomorphine challenge evoked an increase in locomotor activity in stimulant-pre-treated rats, reflecting dopamine receptor supersensitivity. SCH23390 pre-treatment inhibited the development of dopamine receptor supersensitivity, while sulpiride demonstrated no inhibitory effects. These results suggest that the dopamine D1 receptor antagonist SCH23390 inhibits the development of dopamine receptor supersensitivity which is associated with the development of CPP.