The role of NMDA receptors of the medial septum and dorsal hippocampus on memory acquisition

The glutamatergic neurons in the medial septal/diagonal band of broca (MS/DB) affect the hippocampal functions by modulating the septo-hippocampal neurons. Our study investigated the possible role of NMDA receptors of the medial septum nucleus (MS) and dorsal hippocampus (CA1) on memory acquisition in male Wistar rats. Animals were bilaterally implanted with chronic cannulae in the MS and CA1. Rats were trained in a step-through type inhibitory avoidance task, and tested 24 h after training to measure step-through latency as memory retrieval. Our results indicated that pre-training intra-MS or intra-CA1 infusions of NMDA (0.125 mu g/rat) and D-AP7 (0.012 mu g/rat) increased and decreased memory acquisition, respectively when compared to saline control group. Also, pre-training intra-CA1 and intra-MS injection of an effect dose of D-AP7 (0.012 mu g/rat) along with an effect dose of NMDA (0.125 mu g/rat) impaired memory acquisition. Interestingly, pre-training intra-CA1/MS infusion of D-AP7 (0.012 mu g/rat) diminished memory response produced by pre-training injection of NMDA (0.125 mu g/rat) in the MS/CA1, respectively (cross injection or bilateral injection). Also, all above doses of drugs did not alter locomotor activity. These results suggest that the glutamatergic pathway between the MS and CA1 regions is involved in memory acquisition process. (C) 2016 Published by Elsevier Inc.