Involvement of nitrergic system of CA1in harmane induced learning and memory deficits.
Harmane (HA) is a β-carboline alkaloid derived from the Peganum harmala plant which induces memory impairment. On the other hand some of the investigations showed that β-carboline alkaloids inhibit NO production. Thus, the aim of the present study was to investigate the role of nitrergic system of the dorsal hippocampus (CA1) in HA-induced amnesia in male adult mice. One-trial step-down passive avoidance and hole-board apparatuses were used for the assessment of memory retrieval and exploratory behaviors respectively. The data indicated that pre-training intraperitoneal (i.p.) administration of HA (12 and 16 mgkg) decreased memory acquisition. Sole pre-training or pre-testing administration of L-NAME, a nitric oxide synthesis inhibitor (5, 10 and 15 μgmice, intra-CA1) did not alter memory retrieval. On the other hand, pre-training (10 and 15 μgmice, intra-CA1) and pre-testing (5, 10 μgmice, intra-CA1) injections of L-NAME restored HA-induced amnesia (16 mgkg, i.p.). Furthermore, neither sole pre-training nor pre-testing administration of l-arginine, a NO precursor (3, 6 and 9 μgmice, intra-CA1), altered memory retrieval. In addition, pre-testing (6 and 9 μgmice, intra-CA1), but not pre-training, injection of l-arginine increased HA-induced amnesia (16 mgkg, i.p.). These results suggest that the nitrergic system of CA1 is involved in HA-induced amnesia.