Different roles of dopamine receptor subtypes in footshock stress-induced enhancement of morphine conditioned place preference

Abstract The present study investigated the involvement of dopamine mechanism in the effect of intermittent footshock stress on the morphine-induced place preference. A single intermittent footshock session significantly enhanced the place preference induced by 3.0 mg/kg morphine. This enhancing effect was inhibited by selective D 1 receptor antagonist SCH23390 and selective D 2 receptor antagonist sulpiride pretreatment 20 min before footshock session, suggesting dopamine D 1 and D 2 receptors are required for the development of intermittent footshock stress-induced enhancement of morphine-associated place preference. However, different from D 1 and D 2 receptors this enhancing effect was blocked by stimulation of dopamine D 3 receptor with selective D 3 receptor agonist 7-OH-DPAT pretreatment 20 min before footshock session which suggest dopamine D 3 receptor play a negative mediation effect on the intermittent footshock stress-induced this enhancement. These results indicate that dopamine D 1 , D 2 , and D 3 receptor subtypes play different roles in footshock stress-induced enhancement of morphine conditioned place preference.