[Effects of L-malate, an inhibitor of glutamate decarboxylase, on learning and memory in mice].

Oral administration of L-malate 600 mg.kg-1 for 5 days before training can significantly promote memory acquisition, consolidation and retrieval, respectively, on anisodine-, chloramphenicol-, and ethanol-induced memory impairment in mice. Ketamine (8.5 mg.kg-1, i.p.), a selective NMDA receptor antagonist, was found to inhibit the anti-amnesic activity of L-malate. The glutamate (Glu) and GABA content in mice brain was measured by high-performance liquid chromatography with fluorescence detection. The content of GABA was shown to be decreased from 2.3 +/- 0.5 mumol.g-1 to 1.3 +/- 0.5 mumol.g-1 (P < 0.01), so the Glu/GABA ratio was increased significantly. These results suggest that the decrease of cerebral GABA level and the increase of Glu/GABA ratio is favorable to learning and memory.