Conditioned aversion after delay place conditioning with amphetamine.

Male, Sprague-Dawley rats received subcutaneous injections of either dextroamphetamine sulfate (AMP; 3.0 mg/kg) or vehicle [VEH (phosphate buffer); 1 ml/kg] immediately before (standard conditioning) or after (delay conditioning) conditioning sessions in a place-conditioning paradigm. AMP was paired for 4 conditioning sessions with one compartment of a three-compartment place-conditioning apparatus; VEH was paired for 4 conditioning sessions with another compartment. Animals were then tested for place preference or aversion by determining the proportion of time spent in each compartment during a 15-minute test session. Standard conditioning with AMP produced a place preference while delay conditioning produced a place aversion. Similar findings had earlier been reported from studies involving conditioned place-preferences and aversions with nicotine. These studies demonstrated that the time of drug administration can be as strong a determinant of place-conditioning effects as the drug itself.