title: GluN1 and GluN2A NMDA Receptor Subunits Increase in the Hippocampus during Memory Consolidation in the Rat.
abstract: It is widely accepted that NMDA receptors (NMDAR) are required for learning and memory formation, and for synaptic plasticity induction. We have previously shown that hippocampal GluN1 and GluN2A NMDAR subunits significantly increased following habituation of rats to an open field (OF), while GluN2B remained unchanged. Similar results were obtained after CA1-long-term potentiation (LTP) induction in rat hippocampal slices. Other studies have also shown NMDAR up regulation at earlier and later time points after LTP induction or learning acquisition. In this work, we have studied NMDAR subunits levels in the hippocampus and prefrontal cortex (PFC) after OF habituation and after object recognition (OR), to find out whether rising of NMDAR subunits is a general and structure-specific feature during memory formation. In 1, 2 and 3 month old rats there was an increase in hippocampal GluN1 and GluN2A, but not in GluN2B levels 70 min after OF habituation. This rise overlaps with early phase of memory consolidation, suggesting a putative relationship between them. The increases fell down to control levels 90 min after training. Similar results were obtained in the hippocampus of adult rats 70 min after OR training, without changes in PFC. Following OF test or OR discrimination phase, NMDAR subunits remained unchanged. Hence, rising of hippocampal GluN1 and GluN2A appears to be a general feature after novel "spatial/discrimination" memory acquisition. To start investigating the dynamics and possible mechanisms of these changes, we have studied hippocampal neuron cultures stimulated by KCl to induce plasticity. GluN1 and GluN2A increased both in dendrites and neuronal bodies, reaching a maximum 75 min later and returning to control levels at 90 min. Translation and/or transcription and mobilization differentially contribute to this rise in subunits in bodies and dendrites. Our results showed that the NMDAR subunits increase follows a similar time course bothin vitroandin vivo. These changes happen in the hippocampus where a spatial representation of the environment is being formed making possible short term and long term memories (STM and LTM); appear to be structure-specific; are preserved along life; and could be related to synaptic tagging and/or to memory consolidation of new spatial/discrimination information.
authors.affiliation: Laboratorio de Neuroplasticidad y Neurotoxinas, Instituto de Biología Celular y Neurociencia, Universidad de Buenos Aires (UBA)-CONICET Buenos Aires, Argentina.
authors.forename: Magali C
authors.initials: MC
authors.lastname: Cercato
authors.affiliation: Laboratorio de Neuroplasticidad y Neurotoxinas, Instituto de Biología Celular y Neurociencia, Universidad de Buenos Aires (UBA)-CONICET Buenos Aires, Argentina.
authors.forename: Cecilia A
authors.initials: CA
authors.lastname: Vázquez
authors.affiliation: Laboratorio de Neuroplasticidad y Neurotoxinas, Instituto de Biología Celular y Neurociencia, Universidad de Buenos Aires (UBA)-CONICET Buenos Aires, Argentina.
authors.forename: Edgar
authors.initials: E
authors.lastname: Kornisiuk
authors.affiliation: Laboratorio de Neuroplasticidad y Neurotoxinas, Instituto de Biología Celular y Neurociencia, Universidad de Buenos Aires (UBA)-CONICET Buenos Aires, Argentina.
authors.forename: Alejandra I
authors.initials: AI
authors.lastname: Aguirre
authors.affiliation: Laboratorio de Neuroplasticidad y Neurotoxinas, Instituto de Biología Celular y Neurociencia, Universidad de Buenos Aires (UBA)-CONICET Buenos Aires, Argentina.
authors.forename: Natalia
authors.initials: N
authors.lastname: Colettis
authors.affiliation: Laboratorio de Neuroplasticidad y Neurotoxinas, Instituto de Biología Celular y Neurociencia, Universidad de Buenos Aires (UBA)-CONICET Buenos Aires, Argentina.
authors.forename: Marina
authors.initials: M
authors.lastname: Snitcofsky
authors.affiliation: Laboratorio de Neuroplasticidad y Neurotoxinas, Instituto de Biología Celular y Neurociencia, Universidad de Buenos Aires (UBA)-CONICETBuenos Aires, Argentina; Ciclo Básico Común-Universidad de Buenos AiresBuenos Aires, Argentina.
authors.forename: Diana A
authors.initials: DA
authors.lastname: Jerusalinsky
authors.affiliation: Laboratorio de Neuroplasticidad y Neurotoxinas, Instituto de Biología Celular y Neurociencia, Universidad de Buenos Aires (UBA)-CONICETBuenos Aires, Argentina; 1UA de Biología Celular, Histología, Embriología y Genética, Departamento de Histología, Facultad de Medicina, Universidad de Buenos AiresBuenos Aires, Argentina.
authors.forename: María V
authors.initials: MV
authors.lastname: Baez
keywords: GluN1; GluN2A; LTM; NMDAR; hippocampus; synaptic plasticity