Relationship between facilitatory effect of piracetam on memory and glutamate receptors

By Y-maze method, repeated administrations of sodium glutamate 400 mg.kg-1.d-1 ip for 5 d before training remarkably reduced the number of trials from 45.3 +/- 15.5 of the control to 20.0 +/- 6.9 in mouse of anisodine-induced memory impairment. Ketamine (10 mg.kg-1, ip), a selective NMDA receptor antagonist, inhibited the anti-amnesic activity of piracetam. The number of memory errors was raised from 1.9 +/- 1.5 to 2.6 +/- 2.1 in mouse step-down test. Piracetam 500 mg.kg-1.d-1 ip for 3 d caused a decrease in mouse brain glutamate content and glutamate/GABA rate from 7.07 +/- 0.83 mumol.g-1 to 5.69 +/- 0.60 mumol.g-1 and 4.98 +/- 0.63 to 4.52 +/- 0.81, respectively. These results suggest that facilitatory effect of piracetam on memory may be mediated by glutamate receptor.