Amphetamine-induced on- and off-wall rearing in adult laboratory rats

Recently, Bauer reported that amphetamine did not increase rearing behavior in adult rats. This result is at variance with many earlier reports demonstrating that amphetamine does increase rearing behavior. Because Bauer's automated measure only detected rearing when it occurred on the wall of the cage, it is possible that amphetamine only increased rearing behavior that occurred off the wall, which was not measured in his study. Bauer also included non-habituated animals in his study which might account for the discrepant results. The present experiment was performed to determine if, indeed, there was a difference between amphetamine induced on- and off-wall rearing and to determine to what extent habituation affected both types of rearing. The findings demonstrated that both types of rearing increased following d-amphetamine administration for both habituated and non-habituated animals. However, at the highest dose of d-amphetamine studied (4 mg/kg) rearing occurred mainly on the wall. Additionally, rearing behavior was found to increase following amphetamine when measured in the Digiscan Animal Activity Monitoring system which detects, but does not discriminate between, both on- and off-wall rearing.