Activity and Responsivity in Rats after Magnesium Pemoline Injections

Rats injected intraperitoneally with magnesium pemoline avoided a buzzing sound (conditioned stimulus) associated with an electric shock to the feet (unconditioned stimulus) more frequently than controls. Drug-injected rats did not avoid the foot shock more frequently than controls, although the experimental rats did have shorter response latencies in the active avoidance task. In subsequent experiments which measured activity changes and response to the buzzing sound alone, it was found that magnesium pemoline caused a lesser decrease in activity level and a more sustained responsivity to the buzzer's sound than did control injections of tragacanth. This may account for the latency differences observed in the avoidance task.