Distribution of NMDA and AMPA receptor subunits at thalamo-amygdaloid dendritic spines

Jason J. Radley, Claudia R. Farb, Yong He, William G M Janssen, Sarina M. Rodrigues, Luke R. Johnson, Patrick R. Hof, Joseph E. LeDoux, John Morrison

Research output: Contribution to journalArticle

47 Scopus citations

Abstract

Synapses onto dendritic spines in the lateral amygdala formed by afferents from the auditory thalamus represent a site of plasticity in Pavlovian fear conditioning. Previous work has demonstrated that thalamic afferents synapse onto LA spines expressing glutamate receptor (GluR) subunits, but the GluR subunit distribution at the synapse and within the cytoplasm has not been characterized. Therefore, we performed a quantitative analysis for α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor subunits GluR2 and GluR3 and N-methyl-d-aspartate (NMDA) receptor subunits NR1 and NR2B by combining anterograde labeling of thalamo-amygdaloid afferents with postembedding immunoelectron microscopy for the GluRs in adult rats. A high percentage of thalamo-amygdaloid spines was immunoreactive for GluR2 (80%), GluR3 (83%), and NR1 (83%), while a smaller proportion of spines expressed NR2B (59%). To compare across the various subunits, the cytoplasmic to synaptic ratios of GluRs were measured within thalamo-amygdaloid spines. Analyses revealed that the cytoplasmic pool of GluR2 receptors was twice as large compared to the GluR3, NR1, and NR2B subunits. Our data also show that in the adult brain, the NR2B subunit is expressed in the majority of in thalamo-amygdaloid spines and that within these spines, the various GluRs are differentially distributed between synaptic and non-synaptic sites. The prevalence of the NR2B subunit in thalamo-amygdaloid spines provides morphological evidence supporting its role in the fear conditioning circuit while the differential distribution of the GluR subtypes may reflect distinct roles for their involvement in this circuitry and synaptic plasticity.

Original languageEnglish (US)
Pages (from-to)87-94
Number of pages8
JournalBrain Research
Volume1134
Issue number1
DOIs
StatePublished - Feb 23 2007
Externally publishedYes

Keywords

  • Electron microscopy
  • Excitatory amino acid
  • GluR2
  • GluR3
  • Immunogold
  • Immunohistochemistry
  • NR1
  • NR2B
  • Postembedding
  • Tracing

ASJC Scopus subject areas

  • Neuroscience(all)
  • Clinical Neurology
  • Developmental Biology
  • Molecular Biology

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    Radley, J. J., Farb, C. R., He, Y., Janssen, W. G. M., Rodrigues, S. M., Johnson, L. R., Hof, P. R., LeDoux, J. E., & Morrison, J. (2007). Distribution of NMDA and AMPA receptor subunits at thalamo-amygdaloid dendritic spines. Brain Research, 1134(1), 87-94. https://doi.org/10.1016/j.brainres.2006.11.045