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

Access to novel objects, similar to drugs of abuse, can enhance a place pre ference in rats. In the present experiments, the dopamine D-1 receptor anta gonist SCH-23390 blocked an increase in place preference conditioned by acc ess to novel objects at doses that did not interfere with object interactio n (0.01 and 0.03 mg/kg) or produce a place aversion in controls. However, e ticlopride, a D-2/D-3 dopamine receptor antagonist, only blocked the condit ioned increase in place preference at a dose (0.3 mg/kg) that impaired obje ct interaction. In contrast, neither SCH-23390 nor eticlopride blocked pref erence for the novel object in an object recognition task at doses that did not interfere with object interaction. These experiments provide further e vidence that the neural processes controlling learned associations between novel stimuli and the environment overlap with drugs of abuse. (C) 1999 Els evier Science B.V. All rights reserved.