EFFECTS OF CAFFEINE AND PD-116,600 ON THE DIFFERENTIAL-REINFORCEMENT-OF-LOW RATE 72-S (DRL 72-S) SCHEDULE OF REINFORCEMENT

Caffeine and PD 116,600 were found to decrease the reinforcement rate and increase the response rate in rats performing under a differential -reinforcement-of-low rate 72-s (DRL 72-s) schedule of reinforcement. In contrast, antidepressant drugs previously have been found to increa se the reinforcement and decrease the response rate. Caffeine has been found to test similar to antidepressant drugs on at least one other b ehavioral screen, but caffeine does not possess clinical antidepressan t properties. These results provide further support for the DRL 72-s s chedule as a behavioral screen for antidepressant drugs.