TY - JOUR
T1 - Synaptic coexistence of AMPA and NMDA receptors in the rat hippocampus
T2 - A postembedding immunogold study
AU - He, Yong
AU - Janssen, William G M
AU - Morrison, John
PY - 1998/11/15
Y1 - 1998/11/15
N2 - 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.
AB - 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.
KW - Electron microscopy
KW - Excitatory amino acids
KW - GABA
KW - GluR2
KW - NMDAR1
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U2 - 10.1002/(SICI)1097-4547(19981115)54:4<444::AID-JNR2>3.0.CO;2-3
DO - 10.1002/(SICI)1097-4547(19981115)54:4<444::AID-JNR2>3.0.CO;2-3
M3 - Article
C2 - 9822155
AN - SCOPUS:0032533749
VL - 54
SP - 444
EP - 449
JO - Journal of Neuroscience Research
JF - Journal of Neuroscience Research
SN - 0360-4012
IS - 4
ER -