Is the NMDA Receptor of the CA1 Region Participated in the Amnesic Effect of Harmane?

ABSTRACT

Aims: In the present study, we investigated the influence of NMDA receptor agonist (N-methyl-d-aspartate) and antagonist (D-AP7) on amnesia induced by a β-carboline alkaloid, harmane. Methodology: Animals implanted with bilateral cannulae at the CA1 regions of the dorsal hippocampus and microinjected with glutamatergic drugs. One-trial step-down was used to assess memory acquisition and then, the hole-board method to assess exploratory behaviors in adult male NMRI mice. Results: The results revealed that pre-training intra-CA1 administration of NMDA (0.5 ng/mouse) and D-AP7 (0.25 and 0.5 ng/mouse) improved and impaired memory acquisition, respectively. Also, pre-training intra-peritoneal (i.p.) administration of harmane (12 mg/kg) decreased memory acquisition. Furthermore, pre-training intra-CA1 injection of sub-threshold dose of NMDA (0.02 ng/mouse) reversed, while non-significant dose of D-AP7 (0.125 ng/mouse) did not change impairment of memory acquisition induced by harmane (12 mg/kg, i.p.). Conclusion: In addition, all above doses of drugs did not alter locomotor activity. These results suggest that the CA1 NMDA receptors are involved in harmane-induced amnesia.