CHANGES IN GLUN1 AND GLUN2A NDMAR SUBUNITS EXPRESSION AFTER HABITUATION TO AN OPEN FIELD.

MAGALI CERCATO; CECILIA VÁZQUEZ; EDGAR KORNISIUK; ALEJANDRA AGUIRRE; MARINA SNITCOFSKY; MARÍA VERÓNICA BÁEZ; DIANA JERUSALINSKY

Congreso; IBRO - 9th World Congress International Brain Research Organization; 2015

NMDA receptors (NMDAR) play a critical role in synaptic plasticity, are required for memory encoding and ?storage?, participate in plasticity during central nervous system (CNS) development, like synaptogenesis and synapse maturation, and also in neurodegenerative disorders like Alzheimer and Parkinson disease (Paoletti et al., 2013). NMDAR are heterotetramers composed by 2 GluN1 obligatory subunits and 2 regulatory subunits, being GluN2A and GluN2B the major regulatory subunits in CNS regions involved in cognitive functions. We have previously shown that about 1 hour after memory acquisition of a hippocampus depending task (open field [OF] habituation) or after the effective induction of LTP in fresh hippocampal slices, GluN1 and GluN2A expression transiently increased in the hippocampus (Baez et al., 2013).In this work we analyze NMDAR subunits levels in Wistar rats after 5 minutes exploration of an unique OF, in central structures other than the hippocampus, at different ages (30, 60 and 90 days old). There was an increase in GluN1 and GluN2A levels in the hippocampus about 1 hour after the OF session, though not in the cerebral cortex or the amygdala; that increase was reversible since the levels were not significant different from controls 24 h later in all ages assessed. We then analyzed two other groups of rats (30 and 90 days old) that were exposed to a second OF session (test). Both groups, rats tested in a 2nd OF session 24 h or up to 2 month after the 1st session, showed habituation to the OF. GluN1 and GluN2A levels increased only in the prefrontal cortex 60 minutes after the test, either 24 hs or 2 months later. Our results suggest that the transient increase and rebalance of specific NMDAR subunits in structures involved in memory processing could be part of the memory tracing.