Synaptic coexistence of AMPA and NMDA receptors in the rat hippocampus: A postembedding immunogold study

Yong He, William G M Janssen, John Morrison

Research output: Contribution to journalArticlepeer-review

62 Scopus citations


Synaptic distributions of N-methyl-D-aspartate (NMDA) and α-amino-3- hydroxy-5-methylisoxazolepropionic acid (AMPA) receptor subunits, NMDAR1 and GluR2, respectively, were examined by electron microscopy with the high spatial resolution of postembedding immunogold localization. We provide direct evidence for colocalization at individual axodendritic asymmetric synapses within the CA1 subfield of rat hippocampus. AMPA/NMDA receptor colocalization was found both in γ-aminobutyric acid (GABA)ergic dendrites and non-GABAergic dendritic shafts, as well as dendritic spines. Some asymmetric synapses were found to contain only NMDAR1 or GluR2; however, most immunopositive synapses contained both subunits. Many NMDAR1 and/or GluR2 immunopositive profiles received GABAergic innervation at an adjacent synapse, providing a substrate for GABAergic modulation of both GluR classes. These data suggest that excitatory neuronal transmission in CA1 neurons may generally involve activation of both NMDA and AMPA receptor subunits at a single synapse, however, they also offer ultrastructural evidence for NMDAR1- only synapses that might represent silent synapses.

Original languageEnglish (US)
Pages (from-to)444-449
Number of pages6
JournalJournal of Neuroscience Research
Issue number4
StatePublished - Nov 15 1998
Externally publishedYes


  • Electron microscopy
  • Excitatory amino acids
  • GABA
  • GluR2
  • NMDAR1

ASJC Scopus subject areas

  • Neuroscience(all)


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