Abstract: In step-down test,diazepam(1 mg·kg^-1 po,1h before training)was shown tosignificantly impair memory acquisition in mice.But piracetam(200 mg·kg^-1 ip,1 h beforetraining)was found to improve the diazepam-induced impairments of learning.By photocell cagemethod,piracetam showed no significant inhibitory effect on the diazepam-induced spontaneous motoractivity in mice.In Y-maze test,Glutamic acid(0.1 μg,icv,3 min before training)significantlyimproved learning in normal mice and the amnesic effect of G ABA and diazepam were completelyantagonized by Glutamic acid and piracetam(200 mg·kg^-1 ip,1h before training). These resultSsuggest that increasing GABA-ergic neuronal transmission is unfavorable to learning and memory,butincreasing Glu-ergic transmission is contrary to the former.It seemed that the presence of Glu/GABAsystem in the brain could regulate learning and memory.