Immunocytochemical Localization of a High-affinity Glutamate-Aspartate Transporter, GLAST, in the Rat and Guinea-pig Cochlea

Glutamate transporters play an important role in the reuptake of glutamate after its release from glutamatergic synapses. Four such transporters have so far been cloned from the rat brain. One, the glutamate‐aspartate transporter GLAST, has been detected in the mammalian cochlea, in which the princi...

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Bibliographic Details
Published in:The European journal of neuroscience 1997-09, Vol.9 (9), p.1961-1969
Main Authors: Furness, David N., Lehre, Knut P.
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Amino Acid Transport System X-AG
Animals
ATP-Binding Cassette Transporters - analysis
Biological Transport
Guinea Pigs
hair cells
Immunoblotting
Immunohistochemistry
Microscopy, Immunoelectron
Molecular Sequence Data
neurotransmitters
organ of Corti
Organ of Corti - chemistry
Rats
Rats, Wistar
spiral ganglion
Spiral Ganglion - chemistry
Subcellular Fractions - chemistry
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Summary:Glutamate transporters play an important role in the reuptake of glutamate after its release from glutamatergic synapses. Four such transporters have so far been cloned from the rat brain. One, the glutamate‐aspartate transporter GLAST, has been detected in the mammalian cochlea, in which the principal afferent synapse of the auditory nerve, between the inner hair cells and neurites of type I spiral ganglion neurons, has been suggested to be glutamatergic. The distribution of GLAST was therefore investigated to provide clues to the handling of glutamate in the cochlea. This was studied using light and electron microscopic immunocytochemistry in rats and guinea pigs with antibodies raised against synthetic peptides based on the sequence for GLAST. Significant immunoreactivity was found in the myelin sheath formed by satellite cells surrounding the type I spiral ganglion neurons, and along the plasma membranes of supporting cells around the inner hair cells; other cells in both locations were only weakly labelled, if at all. The absence of substantial numbers of synapses in the spiral ganglion suggests that GLAST is unlikely to be associated with the uptake of synaptic glutamate after release in this region. lmmunoreactivity associated with the inner hair cells is consistent with the utilization of glutamate at the afferent synapse.
ISSN:0953-816X
1460-9568
DOI:10.1111/j.1460-9568.1997.tb00763.x