Expression of GluN1 and GluN2A subunits of NMDA receptor increases after KCl depolarization of cultured neurons from rat hippocampus.

AGUIRRE AI; CERCATO MC; BAEZ MV; JERUSALINSKY DA

Huerta Grande

Congreso; XXVII Reunión Anual Sociedad Argentina de Investigación en Neurociencias.; 2012

Sociedad Argentina de Investigación en Neurociencias

NMDA receptors (NMDAR) are tetramers containing two GluN1 and two variable regulatory subunits which determine some functional properties. In rat hippocampus major regulatory subunits are GluN2A and GluN2B. Our recent results show that in rat hippocampus, GluN1 and GluN2A, though not GluN2B levels, are significantly higher at 70 min, but not at 30 min following a 5 min open field session (Snitcofsky et al.). Similar changes took place after LTP induction in hippocampal slices (Cercato et al.). To investigate where are these changes expressed, primary cultures of rat hippocampal neurons were stimulated with pulses of KCl to induce LTP-like plasticity (Wu et al., 2001); the subunits were assessed by immunocytochemistry 0, 30 and 70 min after KCl . LTP-induced increase of NMDAR puncta, as reported by Barria and Malinow in hippocampal slices (2002), was verified in dendritic spines 30 min after KCl stimulation, while total immunofluorescence did not change. This could be due to transport along the membrane from extrasynaptic sites and/or delivery from subsynaptic pools. However, 70 minutes after KCl stimulation an increase in total immunofluorescence, as well as in the number of spines expressing GluN1 and GluN2A, was evidenced. No changes were observed for GluN2B. These results are in agreement with those we obtained from electrophysiological and behavioral assays, strongly supporting the possibility that these changes are actually expressed in NMDAR at the synapses.