We describe here a novel effect of activity on the subcellular distribution of NMDA receptors in hippocampal neurons in culture. In spontaneously active neurons, NMDA receptors were clustered at a few synaptic and nonsynaptic sites. Chronic blockade of NMDA receptor activity induced a 380% increase in the number of NMDA receptor clusters and a shift to a more synaptic distribution. This effect was reversible. The distributions of the presynaptic marker synaptophysin, the AMPA-type glutamate receptor subunit GluR1, and the putative NMDA receptor clustering protein PSD-95 were not affected by blockade. Regulation of the synaptic localization of NMDA receptors by activity may define a novel mechanism by which input controls a neuron's ability to modify its synapses.
Rao, A., & Craig, A. M. (1997). Activity regulates the synaptic localization of the NMDA receptor in hippocampal neurons. Neuron, 19(4), 801–812. https://doi.org/10.1016/S0896-6273(00)80962-9