Acute versus chronic NMDA receptor blockade and synaptic AMPA receptor delivery

Anatomical and electrophysiological experiments1,2,3,4,5,6 show that central excitatory synapses initially display NMDA (N-methyl-d-aspartate) receptors (NMDARs) and subsequently mature by acquiring AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptors (AMPARs). NMDAR activation can lead to rapid synaptic delivery of AMPARs ('AMPAfication')7,8, but the view that AMPAfication during development requires NMDAR activation has been challenged by studies showing that chronic removal of NMDAR function (either genetically9,10 or pharmacologically11,12,13,14) has no apparent effect on acquisition of AMPAR-mediated synaptic transmission. Here we show that NMDARs are crucial in the developmental acquisition of AMPAR-mediated synaptic transmission, and that chronic disabling of NMDAR function triggers compensatory mechanisms for NMDAR-independent AMPAfication.