Influence of para-chlorophenylalanine on the memory-facilitating effect of central stimulants

In experiments with albino rats, trained and tested for memory after 24 hours in a multiunit semiautomated maze, it was found that the following drugs: para-chlorophenylalanine (pCPA) in a dose of 300 mg/kg i. p. 24 hours before training caffeine--5 mg/kg i. p. 5 min before training or 20 mg/kg i. p. immediately after training, strychnine--1 mg/kg i. p. 5 min before or immediately after training and amphetamine--1 mg/kg i. p. 15 min before and immediately after training, facilitate learning and/or the memory of the experimental animals. Combined application of pCPA and the central stimulants studied (in the doses and schedules indicated) potentiates the learning- and memory-facilitating effect of the stimulants. It is assumed that the lowered cerebral serotonin activity is essential for the manifestation of the memory effects of the central stimulants and for the optimum course of the processes responsible for the formation and storage of the memory traces.