Chemical Senses Advance Access originally published online on January 8, 2008
Chemical Senses 2008 33(2):201-210; doi:10.1093/chemse/bjm079
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Sensory Deafferentation Transsynaptically Alters Neuronal GluR1 Expression in the External Plexiform Layer of the Adult Mouse Main Olfactory Bulb
1 Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932, USA 2 Department of Anatomy and Neurobiology and Program in Neuroscience, University of Maryland, Baltimore, MD 21201, USA 3 Department of Gene Technology and Developmental Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
Correspondence to be sent to: Kathryn Hamilton, Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932, USA. e-mail: khamil{at}lsuhsc.edu
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Abstract |
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Altered distribution of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor subunit GluR1 has been linked to stimulation-dependent changes in synaptic efficacy, including long-term potentiation and depression. The main olfactory bulb (OB) remains plastic throughout life; how GluR1 may be involved in this plasticity is unknown. We have previously shown that neonatal naris occlusion reduces numbers of interneuron cell bodies that are immunoreactive for GluR1 in the external plexiform layer (EPL) of the adult mouse OB. Here, we show that immunoreactivity of mouse EPL interneurons for GluR1 is also dramatically reduced following olfactory deafferentation in adulthood. We further show that expression of glutamic acid decarboxylase (GAD) 65, 1 of 2 GAD isoforms expressed by adult gamma-aminobutyric acidergic interneurons, is reduced, but to a much smaller extent, and that in double-labeled cells, immunoreactivity for the Ca2+-binding protein parvalbumin (PV) is also reduced. In addition, GluR1 expression is reduced in presumptive tufted cells and interneurons that are negative for GAD65 and PV. Consistent with previous reports, sensory deafferentation resulted in little neuronal degeneration in the adult EPL, indicating that these differences were not likely due to death of EPL neurons. Together, these results suggest that olfactory input regulates expression of the GluR1 AMPA receptor subunit by tufted cells that may in turn regulate GluR1 expression by interneurons within the OB EPL.
Key words: AMPA receptor, confocal microscopy, immunohistochemistry, olfaction, optical disector, plasticity
Accepted 1 November 2007