Rapid Spine Delivery and Redistribution of AMPA Receptors After Synaptic NMDA Receptor Activation

TLDR

The study aimed to monitor changes in AMPA receptor distribution in living neurons. This was accomplished by tagging the GluR1 subunit with green fluorescent protein. Tetanic stimulation rapidly delivered functional, transiently expressed GluR1‑GFP from intracellular stores into dendritic spines and clusters in a NMDA‑dependent manner, a process that may underlie enhanced AMPA‑mediated transmission during long‑term potentiation and synaptic maturation.

Abstract

To monitor changes in α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor distribution in living neurons, the AMPA receptor subunit GluR1 was tagged with green fluorescent protein (GFP). This protein (GluR1-GFP) was functional and was transiently expressed in hippocampal CA1 neurons. In dendrites visualized with two-photon laser scanning microscopy or electron microscopy, most of the GluR1-GFP was intracellular, mimicking endogenous GluR1 distribution. Tetanic synaptic stimulation induced a rapid delivery of tagged receptors into dendritic spines as well as clusters in dendrites. These postsynaptic trafficking events required synaptic N -methyl- d -aspartate (NMDA) receptor activation and may contribute to the enhanced AMPA receptor–mediated transmission observed during long-term potentiation and activity-dependent synaptic maturation.