BACKGROUND AND AIM: The anatomical connections of septum and hippocampus and the influence of cholinergic and glutamatergic projections in these sites have been reported. In the present study, the effect of pre-training intra-dorsal hippocampal (CA1) and intra-medial septal (MS) administration of scopolamine, a nonselective muscarinic acetylcholine antagonist, and NMDA receptor agents and their interactions, on acquisition of memory have been investigated. METHODS: The animals were bilaterally implanted with chronic cannulae in the CA1 regions and in the medial septum. Animals were trained in a step-through type inhibitory avoidance task, and tested 24h after training to measure step-through latency as memory retrieval. RESULTS: Intra-CA1 or intra-MS injections of scopolamine (0.5, 1 and 2 μg/rat) and D-AP7 (a competitive NMDA receptor antagonist; 0.025, 0.05 and 0.1 μg/rat) reduced, while NMDA (0.125 and 0.25 μg/rat) increased memory. Intra-MS injection of a subthreshold dose of NMDA reduced scopolamine induced amnesia in the MS. However, similar injection of NMDA into CA1 did not alter scopolamine response when injected into CA1. Moreover, intra-MS or -CA1 injection of a subthreshold dose of NMDA did not alter scopolamine response in the CA1 or MS respectively. On the other hand, co-administration subthreshold doses of D-AP7 and scopolamine into CA1 and/or MS induced amnesia. CONCLUSIONS: The cholinergic system between septum and CA1 are modulating memory acquisition processes induced by glutamatergic system in the CA1 or septum and co-activation of these systems in these sites can influence learning and memory.
BACKGROUND AND AIM: The anatomical connections of septum and hippocampus and the influence of cholinergic and glutamatergic projections in these sites have been reported. In the present study, the effect of pre-training intra-dorsal hippocampal (CA1) and intra-medial septal (MS) administration of scopolamine, a nonselective muscarinic acetylcholine antagonist, and NMDA receptor agents and their interactions, on acquisition of memory have been investigated. METHODS: The animals were bilaterally implanted with chronic cannulae in the CA1 regions and in the medial septum. Animals were trained in a step-through type inhibitory avoidance task, and tested 24h after training to measure step-through latency as memory retrieval. RESULTS: Intra-CA1 or intra-MS injections of scopolamine (0.5, 1 and 2 μg/rat) and D-AP7 (a competitive NMDA receptor antagonist; 0.025, 0.05 and 0.1 μg/rat) reduced, while NMDA (0.125 and 0.25 μg/rat) increased memory. Intra-MS injection of a subthreshold dose of NMDA reduced scopolamine induced amnesia in the MS. However, similar injection of NMDA into CA1 did not alter scopolamine response when injected into CA1. Moreover, intra-MS or -CA1 injection of a subthreshold dose of NMDA did not alter scopolamine response in the CA1 or MS respectively. On the other hand, co-administration subthreshold doses of D-AP7 and scopolamine into CA1 and/or MS induced amnesia. CONCLUSIONS: The cholinergic system between septum and CA1 are modulating memory acquisition processes induced by glutamatergic system in the CA1 or septum and co-activation of these systems in these sites can influence learning and memory.
Authors: Marta Portero-Tresserra; Paula Cristóbal-Narváez; Margarita Martí-Nicolovius; Gemma Guillazo-Blanch; Anna Vale-Martínez Journal: PLoS One Date: 2013-08-02 Impact factor: 3.240