The effect of baclofen and AP-7 on selected behavior in rats.

Synaptic plasticity, cognitive performance, learning, and memory appear to be determined by the balance between GABAergic inhibitory and glutaminergic excitatory amino acids (EAA). To evaluate this role of amino acids the effects of baclofen (0.5 mg/kg IP), GABA-B receptor agonist and AP-7 (5 nmol ICV)-NMDA (N-methyl-D-aspartate) receptor antagonist on the processes of retrieval, consolidation of conditioned reflexes, object recognition, and locomotor activity were tested in rats. Neither AP-7 nor baclofen alone changed locomotor activity, but coadministration of AP-7 and baclofen significantly decreased this activity in the open-field test. Neither AP-7 nor baclofen influenced retrieval or consolidation in the passive avoidance situation when administered alone. Significantly prolonged retrieval and consolidation were observed when AP-7 and baclofen were given together. We did not find differences in effects of either AP-7 or baclofen on object recognition, regardless whether administered alone or in combination.