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Expression of NR2 receptor subunit in rat somatic sensory cortex: Synaptic distribution and colocalization with NR1 and PSD‐95
Author(s) -
Valtschanoff Juli G.,
Burette Alain,
Wenthold Robert J.,
Weinberg Richard J.
Publication year - 1999
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(19990809)410:4<599::aid-cne7>3.0.co;2-4
Subject(s) - neuropil , colocalization , biology , postsynaptic potential , postsynaptic density , immunocytochemistry , nmda receptor , neocortex , neuroscience , microbiology and biotechnology , immunolabeling , synaptophysin , glutamate receptor , endoplasmic reticulum , immunoelectron microscopy , receptor , biophysics , central nervous system , biochemistry , endocrinology , immunohistochemistry , immunology
Functional N ‐methyl‐ d ‐aspartate (NMDA) receptors comprise heteromeric combinations of NR1 and NR2 subunits. In the present study, we employed light and electron microscopic immunocytochemistry to study the expression of NR2A and NR2B (NR2A/B) protein in somatic sensory cortex of adult rats. To relate this distribution to that of NR1 and to the NMDA receptor anchoring protein PSD‐95, we documented extensive cellular colocalization of NR2A/B with NR1 at the light microscopic level. In contrast, PSD‐95 exhibited little somatic staining, being restricted mainly to dendrites and neuropil. We employed postembedding immunocytochemistry to study the ultrastructural expression of NR2A/B. Labeling in neuronal perikarya was associated with rough endoplasmic reticulum and Golgi apparatus; in dendrites, gold particles labeled microtubules. The preponderance of labeling was associated with asymmetric synapses. Double immunolabeling revealed that NR2 colocalized in many synapses with NR1 and with PSD‐95. Quantitative measurements revealed that density of gold particles coding for both NR2 and PSD‐95 was highest just inside the postsynaptic membrane. Tangentially along the membrane, gold particles were concentrated at the synaptic specialization. These data provide structural evidence in neocortex for heteromeric NMDA receptors anchored at the postsynaptic membrane. J. Comp. Neurol. 410:599–611, 1999. © 1999 Wiley‐Liss, Inc.