AMPA-receptor activation is involved in the antiamnesic effect of DM 232 (unifiram) and DM 235 (sunifiram)
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DM 232 and DM 235 are novel antiamnesic compounds structurally related to ampakines. The involvement of AMPA receptors in the mechanism of action of DM 232 and DM 235 was, therefore, investigated in vivo and in vitro. Both compounds (0.1 mg/kg−1 i.p.) were able to reverse the amnesia induced by the AMPA receptor antagonist NBQX (30 mg/kg−1 i.p.) in the mouse passive avoidance test. At the effective doses, the investigated compounds did not impair motor coordination, as revealed by the rota rod test, nor modify spontaneous motility and inspection activity, as revealed by the hole board test. DM 232 and DM 235 reversed the antagonism induced by kynurenic acid of the NMDA-mediated release of [3H]NA in the kynurenate test performed in rat hippocampal slices. This effect was abolished by NBQX. DM 232 increases, in a concentration dependent manner, excitatory synaptic transmission in the rat hippocampus in vitro. These results suggest that DM 232 and DM 235 act as cognition enhancers through the activation of the AMPA-mediated neurotransmission system.