GluR1-immunopositive interneurons in rat neocortex.
Recent in vitro studies suggest that inhibitory interneurons in cortex may express the GluR1 glutamate receptor subunit in the absence of GluR2, leading to calcium-permeable alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) channels. We performed a study of rat somatic sensory cortex to confirm and extend these observations, using quantitative immunocytochemistry for multiple antigens. A morphologically distinct subpopulation of nonpyramidal neurons in neocortex was intensely immunoreactive for GluR1. Electron microscopic analysis of these cells revealed somatic staining for GluR1, mainly in the rough endoplasmic reticulum. Dendritic staining was concentrated at the synaptic active zone and in the adjacent subsynaptic cytoplasm. Double immunostaining revealed that the large majority of intensely GluR1-positive cells contained gamma-aminobutyric acid or its synthetic enzyme, glutamic acid decarboxylase, but little or no GluR2. Thus, AMPA receptors on a subpopulation of inhibitory interneurons in cortex are likely to be calcium permeable. This calcium permeability is likely to influence functional properties of these neurons; it may underlie the high levels of calcium-binding proteins they contain; and may render them liable to excitotoxic injury
Kharazia
V N
VN
Department of Cell Biology and Anatomy, University of North Carolina, Chapel Hill 27599, USA. kharazia@med.unc.edu
Wenthold
R J
RJ
Weinberg
R J
RJ
D000818:Animals; D002540:Cerebral Cortex / Q000737:chemistry / Q000166:cytology*; D005968:Glutamate Decarboxylase / Q000032:analysis; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D007395:Interneurons / Q000737:chemistry* / Q000201:enzymology / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D051381:Rats; D017207:Rats, Sprague-Dawley / Q000033:anatomy & histology*; D018091:Receptors, AMPA / Q000032:analysis*; D013194:Staining and Labeling; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D005968:Glutamate Decarboxylase; D018091:Receptors, AMPA; D005680:gamma-Aminobutyric Acid