Dissociation of cycloheximide's effects on activity from its effects on memory

Two doses of cycloheximide (CYC) were used to dissociate the effect of this drug on locomotor activity from its effect on memory. Results indicated significant short-term (30′–40′) and long-term (24 hr) increases in locomotor activity occur at both CYC doses, whereas significant short- and long-term decreases in step-out latencies in a passive-avoidance task occur primarily at the higher CYC dose. Pargyline, a monoamine oxidase inhibitor, significantly increases locomotor activity but does not decrease step-out latencies in the passive-avoidance task. It is concluded that the decreases in step-out latencies shown by CYC-treated animals in the passive avoidance task are the result of an amnesic effect of CYC rather than its effect on locomotor activity.