Distribution of AMPA-type glutamate receptor subunits in the chick visual system.
Several glutamate receptor (GluR) subunits have been characterized during the past few years. In the present study, subunit-specific antisera were used to determine the distribution of the AMPA-type glutamate receptor subunits GluR1-4 in retinorecipient areas of the chick brain. Six white leghorn chicks (Gallus gallus, 7-15 days old, unknown sex) were deeply anesthesized and perfused with 4% buffered paraformaldehyde and brain sections were stained using immunoperoxidase techniques. The AMPA-type glutamate receptor subunits GLuR1, GluR2/3 and GluR4 were present in several retinorecipient areas, with varying degrees of colocalization. For example perikarya in layers 2, 3, and 5 of the optic tectum contained GluR1, whereas GluR2/3 subunits appeared mainly in neurons of layer 13. The GluR4 subunit was only detected in a few cells of the tectal layer 13. GluR1 and GluR2/3 were observed in neurons of the nucleus geniculatus lateralis, whereas GluR4 was only present in its neuropil. Somata in the accessory optic nucleus appeared to contain GluR2/3 and GluR4, whereas GluR1 was the dominant subunit in the neuropil of this nucleus. These results suggest that different subpopulations of visual neurons might express different combinations of AMPA-type GluR subunits, which in turn might generate different synaptic responses to glutamate derived from retinal ganglion cell axons.
Pires
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RS
Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Brasil. raquel@bmb.icb1.usp.br
Britto
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LR
D000818:Animals; D002645:Chickens; D018091:Receptors, AMPA / Q000502:physiology*; D017470:Receptors, Glutamate / Q000502:physiology*; D014795:Visual Pathways / Q000033:anatomy & histology / Q000502:physiology*
D018091:Receptors, AMPA; D017470:Receptors, Glutamate