Numbers, Densities, and Colocalization of AMPA- and NMDA-Type Glutamate Receptors at Individual Synapses in the Superficial Spinal Dorsal Horn of Rats

Ionotropic glutamate receptors play important roles in spinal processing of nociceptive sensory signals and induction of central sensitization in chronic pain. Here we applied highly sensitive freeze-fracture replica labeling to laminae I-II of the spinal dorsal horn of rats and investigated the num...

Full description

Saved in:
Bibliographic Details
Published in:The Journal of neuroscience 2008-09, Vol.28 (39), p.9692-9701
Main Authors: Antal, Miklos, Fukazawa, Yugo, Eordogh, Maria, Muszil, Dora, Molnar, Elek, Itakura, Makoto, Takahashi, Masami, Shigemoto, Ryuichi
Format: Article
Language:English
Subjects:
Animals
Dendrites - physiology
Dendrites - ultrastructure
Freeze Fracturing - methods
Male
Posterior Horn Cells - cytology
Posterior Horn Cells - metabolism
Rats
Rats, Wistar
Receptors, AMPA - metabolism
Receptors, N-Methyl-D-Aspartate - metabolism
Spinal Cord - cytology
Synapses - metabolism
Synapses - ultrastructure
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Ionotropic glutamate receptors play important roles in spinal processing of nociceptive sensory signals and induction of central sensitization in chronic pain. Here we applied highly sensitive freeze-fracture replica labeling to laminae I-II of the spinal dorsal horn of rats and investigated the numbers, densities, and colocalization of AMPA- and NMDA-type glutamate receptors at individual postsynaptic membrane specializations with a high resolution. All glutamatergic postsynaptic membranes in laminae I-II expressed AMPA receptors, and most of them (96%) were also immunoreactive for the NR1 subunit of NMDA receptors. The numbers of gold particles for AMPA and NMDA receptors at individual postsynaptic membranes showed a linear correlation with the size of postsynaptic membrane specializations and varied in the range of 8-214 and 5-232 with median values of 37 and 28, whereas their densities varied in the range of 325-3365/microm(2) and 102-2263/microm(2) with median values of 1115/microm(2) and 777/microm(2), respectively. Virtually all (99%) glutamatergic postsynaptic membranes expressed GluR2, and most of them (87%) were also immunoreactive for GluR1. The numbers of gold particles for pan-AMPA, NR1, and GluR2 subunits showed a linear correlation with the size of postsynaptic surface areas. Concerning GluR1, there may be two populations of synapses with high and low GluR1 densities. In synapses larger than 0.1 microm(2), GluR1 subunits were recovered in very low numbers. Differential expression of GluR1 and GluR2 subunits suggests regulation of AMPA receptor subunit composition by presynaptic mechanism.
ISSN:0270-6474
1529-2401
DOI:10.1523/JNEUROSCI.1551-08.2008