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Journal of Neurochemistry
Article . 2005 . Peer-reviewed
License: Wiley Online Library User Agreement
Data sources: Crossref
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Evidence for low GluR2 AMPA receptor subunit expression at synapses in the rat basolateral amygdala

Authors: Divina S, Gryder; Dora C, Castaneda; Michael A, Rogawski;

Evidence for low GluR2 AMPA receptor subunit expression at synapses in the rat basolateral amygdala

Abstract

AbstractFast excitatory synaptic responses in basolateral amygdala (BLA) neurons are mainly mediated by ionotropic glutamate receptors of the α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA) subtype. AMPA receptors containing an edited GluR2 subunit are calcium impermeable, whereas those that lack this subunit are calcium permeable and also inwardly rectifying. Here, we sought to determine the extent to which synapses in the rat BLA have AMPA receptors with GluR2 subunits. We assessed GluR2 protein expression in the BLA by immunocytochemistry with a GluR2 subunit‐specific antiserum at the light and electron microscopic level; for comparison, a parallel examination was carried out in the hippocampus. We also recorded from amygdala brain slices to examine the voltage‐dependent properties of AMPA receptor‐ mediated evoked synaptic currents in BLA principal neurons. At the light microscopic level, GluR2 immunoreactivity was localized to the perikarya and proximal dendrites of BLA neurons; dense labeling was also present over the pyramidal cell layer of hippocampal subfields CA1 and CA3. In electron micrographs from the BLA, most of the synapses were asymmetrical with pronounced postsynaptic densities (PSD). They contained clear, spherical vesicles apposed to the PSD and were predominantly onto spines (86%), indicating that they are mainly with BLA principal neurons. Only 11% of morphological synapses in the BLA were onto postsynaptic elements that showed GluR2 immunoreactivity, in contrast to hippocampal subfields CA1 and CA3 in which 76% and 71% of postsynaptic elements were labeled (p < 0.001). Synaptic staining in the BLA and hippocampus, when it occurred, was exclusively postsynaptic, and particularly heavy over the PSD. In whole‐cell voltage clamp recordings, 72% of BLA principal neurons exhibited AMPA receptor‐mediated synaptic currents evoked by external capsule stimulation that were inwardly rectifying. Although BLA principal neurons express perikaryal and proximal dendritic GluR2 immunoreactivity, few synapses onto these neurons express GluR2, and a preponderance of principal neurons have inwardly rectifying AMPA‐mediated synaptic currents, suggesting that targeting of GluR2 to synapses is restricted. Many BLA synaptic AMPA receptors are likely to be calcium permeable and could play roles in synaptic plasticity, epileptogenesis and excitoxicity.

Keywords

Male, Patch-Clamp Techniques, Pyramidal Cells, Presynaptic Terminals, Synaptic Membranes, Excitatory Postsynaptic Potentials, Glutamic Acid, Dendrites, Amygdala, Hippocampus, Immunohistochemistry, Rats, Rats, Sprague-Dawley, Protein Subunits, Organ Culture Techniques, Microscopy, Electron, Transmission, Synapses, Animals, Calcium Signaling, Receptors, AMPA

  • BIP!
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    This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
    14
    popularity
    This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
    Top 10%
    influence
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    impulse
    This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
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citations
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
14
Top 10%
Average
Average
bronze