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AMPA glutamate receptor subunit 2 in normal and visually deprived macaque visual cortex
Margaret T T Wong-Riley1, Paulette Jacobs
1Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee 53226, USA. MWR@MCW.edu
Visual Neuroscience
|January 1, 2003
Summary
This study reveals that the GluR2 subunit of AMPA receptors has a distinct laminar distribution in the macaque visual cortex. Visual input regulates GluR2 levels in specific cortical layers, impacting synaptic transmission.
Area of Science:
- Neuroscience
- Visual Cortex Research
- Synaptic Transmission
Background:
- Glutamate receptors, particularly AMPA receptors, are crucial for excitatory synaptic transmission in the central nervous system.
- The GluR2 subunit of AMPA receptors is significant for controlling calcium (Ca2+) permeability.
- Previous research often studied GluR2 in conjunction with other AMPA subunits.
Purpose of the Study:
- To investigate the distinct laminar distribution of the GluR2 subunit in the normal macaque visual cortex.
- To examine the correlation between GluR2 distribution and cytochrome oxidase (CO) patterns.
- To assess the impact of monocular deprivation on GluR2 distribution.
Main Methods:
- Immunohistochemistry for GluR2 and cytochrome oxidase (CO) in normal and monocularly deprived macaque visual cortex.
- In situ hybridization using a GluR2 cDNA fragment.
- Monocular impulse blockade using tetrodotoxin (TTX).
Main Results:
- In normal adult cortex, GluR2 immunoreactivity (ir) showed a patchy distribution in layers II/III and VI, distinct from CO-rich layers IVC and IVA.
- Fetal GluR2 labeling exhibited a unique honeycomb pattern in layer IVA.
- Monocular impulse blockade induced alternating rows of strong and weak GluR2-ir, correlating with ocular dominance columns.
Conclusions:
- Cortical layers exhibit differential glutamate influence, with low GluR2 in major geniculate-recipient layers (IVC, IVA) potentially favoring Ca2+-permeable receptors.
- GluR2 is more critical in supragranular and infragranular layers for processing visual information.
- Visual input and neuronal activity regulate GluR2 maintenance in output layers, as shown by monocular deprivation effects.