GluN2B SUBUNITS OF THE NMDA RECEPTOR CONTRIBUTE TO THE AMPA RECEPTOR INTERNALIZATION DURING LONG-TERM DEPRESSION IN THE LATERAL AMYGDALA OF JUVENILE RATS

The lateral nucleus of the amygdala (LA) is a critical structure involved in fear conditioning We recently showed that regulated exocytosis and endocytosis of postsynaptic A-ami no 3-hydroxy 5 methylisoxazole-4-propionate subtype of glutamate receptors (AMPARs) are involved in the expression of N methyl D-aspartate subtype glutamate receptors (NMDARs) dependent long term potentiation (LIP) and long term depression (LTD) in coronal slices of the LA However the molecular mechanisms of this effect remain unclear In the present study we investigated the role of distinct NMDAR subtypes in the endocytosis of AMPARs during LTD expression at the synapses of the thalamic inputs to the LA neurons Here we show that the NMDARs antagonist DL 2 amino-5-phosphonovalerate (D APV) blocked the induction of LTD and thus prevented endocytosis of surface AMPARs, indicating that NMDAR activation enhanced the internalization of AMPARs in LTD expression Furthermore, the selective blocking of GluN2B con taming NMDARs completely abolished the NMDAR induced AMPAR endocytosis, whereas preferential inhibition of GluN2A containing NMDARs did not block the NMDAR induced AM PAR endocytosis during LTD expression These results suggest that there exist a preferred NMDAR subtype for AMPAR internalization and activation of GluN2B-containing NMDARs represent the predominate pathway triggered during the early stages of this NMDAR induced endocytosis of AMPARs during LTD in the thalamic inputs to the LA of juvenile rats (C) 2010 IBRO Published by Elsevier Ltd All rights reserved