Dopamine antagonism in a novel-object recognition and a novel-object place conditioning preparation with rats

Access to novel objects, similar to drugs of abuse, can enhance a place preference in rats. In the present experiments, the dopamine D₁ receptor antagonist SCH-23390 blocked an increase in place preference conditioned by access to novel objects at doses that did not interfere with object interaction (0.01 and 0.03 mg/kg) or produce a place aversion in controls. However, eticlopride, a D₂/D₃ dopamine receptor antagonist, only blocked the conditioned increase in place preference at a dose (0.3 mg/kg) that impaired object interaction. In contrast, neither SCH-23390 nor eticlopride blocked preference for the novel object in an object recognition task at doses that did not interfere with object interaction. These experiments provide further evidence that the neural processes controlling learned associations between novel stimuli and the environment overlap with drugs of abuse.