?NMDA receptor subunits expression in the hippocampus after habituation to a new environment?

CERCATO MAGALÍ CECILIA; SNITCOFSKY MARINA; COLETTIS NATALIA; KORNISIUK EDGAR; AGUIRRE ALEJANDRA INÉS; BAEZ MARÍA VERONICA; JERUSALINSKY DIANA

Milan

Congreso; 9th FENS Forum of Neuroscience; 2014

NMDA receptors (NMDAR) play a critical role in synaptic plasticity (as long-term potentiation [LTP] and depression [LTD]), and is required for memory encoding and storage. NMDAR are tetramers composed of 2 (GluN1) obligatory subunits and 2 regulatory subunits (GluN2, GluN3). GluN2A and Glu2NB are the predominant subunits in the hippocampus. We studied GluN1, GluN2A and GluN2B levels in adult rat hippocampus after exploration of an open field (OF). Rats were exposed to an OF for 5 minutes or just for 1 minutes (as control for novelty); they were euthanized at different times (0, 30 or 70 min), and both hippocampi were dissected and homogenized to analyze the subunits by western blot. As control of locomotion and exploratory behavior, rats were twice exposed for 5 min to the OF in two consecutive days and then euthanized 70 minutes. GluN1 and GluN2A levels significantly increased after 70 min of a single 5 min OF session, while GluN2B level did not significantly change. This increase was not observed in rats that explored  only 1 minute the OF or  explored twice the OF for 5 minutes indicating that habituation, rather than just  novelty or exploration, would be related to the change in NMDAR subunits levels. This increase in GluN1 and GluN2A was transient; GluN1 returned to a similar level to that of​​ the group exposed 5 min to the OF and studied immediately (5-0) 180 minutes after the OF; while GluN2A reached that control value 240 minutes following the OF exploration.