Independence of amphetamine reward from locomotor stimulation demonstrated by conditioned place preference.

The conditioned place preference (CPP) paradigm is used widely as a measure of a drug's rewarding properties. The present study examined whether the CPP produced by amphetamine is dependent on the locomotor stimulation that is produced by the drug. An earlier study (Swerdlow and Koob 1984) found that interfering with locomotor stimulation using restraint during the drug treatment blocked CPP. The present study examined whether this effect of restraint was indeed due to restriction of locomotion or was due to restraint maintaining the stimulus novelty of the CPP apparatus. The first experiment showed that novelty of the apparatus itself was a potent factor in the CPP paradigm and was capable of producing a place preference. The second experiment showed that restraint alone could produce a CPP, as would be expected if it maintained stimulus novelty of the apparatus. It also showed that although a CPP to amphetamine could be blocked by restraining the animals during drug treatment, prior habituation to the apparatus to reduce stimulus novelty before treatment negated the effect of restraint on amphetamine CPP. These results indicate that rats can demonstrate a CPP produced by amphetamine even when their activity is restrained. This suggests that the drug's rewarding properties are not dependent on locomotor stimulation.