Role of the biogenic amines in the reversal of cycloheximide-induced amnesia.

Amnesia was induced by pretraining injections of cycloheximide (CYC) in a food motivated discrimination reversal task. Magnitude of amnesia varied as a function of the amount of training on both the initial discrimination and the reversal and also as a function of the length of intertrial interval used on both the reversal and the test. Memory spontaneously recovered 48 hr. following reversal training. Recovery from amnesia was induced by pretesting injections of d-amphetamine and 2 monoamine oxidase inhibitors, pargyline and catron. This enhanced performance was a true recovery of the memory and not a result of enhanced learning or increased arousal. Depletion of catecholamines by alpha-methyl-para-tyrosine, a tyrosine hydroxylase inhibitor, and diethyldithiocarbamate, a dopamine beta hydroxylase inhbitor, resulted in an amnesia quantitatively and qualitatively similar to amnesia induced by CYC. These data support the hypothesis that CYC-induced amnesia is mediated via central catecholamines.