Transient Ca2+-permeable AMPA receptors in postnatal rat primary auditory neurons

Michel Eybalin, Diego A Caicedo-Vierkant, Nicole Renard, Jérôme Ruel, Jean Luc Puel

Research output: Contribution to journalArticle

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Abstract

Fast excitatory transmission in the nervous system is mostly mediated by α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors whose subunit composition governs physiological characteristics such as ligand affinity and ion conductance properties. Here, we report that AMPA receptors at inner hair cell (IHC) synapses lack the GluR2 subunit and are transiently Ca2+-permeable before hearing onset as evidenced using agonist-induced Co2+ accumulation, Western blots and GluR2 confocal microscopy in the rat cochlea. AMPA (100 μM) induced Co2+ accumulation in primary auditory neurons until postnatal day (PND) 10. This accumulation was concentration-dependent, strengthened by cyclothiazide (50 μM) and blocked by GYKI 52466 (80 μM) and Joro spider toxin (1 μM). It was unaffected by D-AP5 (50 μM), and it could not be elicited by 56 mM K + or 1 mM NMDA + 10 μM glycine. Western blots showed that GluR1 immunoreactivity, present in homogenates of immature cochleas, had disappeared by PND12. GluR2 immunoreactivity was not detected until PND10 and GluR3 and GluR4 immunoreactivities were detected at all the ages examined. Confocal microscopy confirmed that the GluR2 immunofluorescence was not located postsynatically to IHCs before PND10. In conclusion, AMPA receptors on maturing primary auditory neurons differ from those on adult neurons. They are probably composed of GluR1, GluR3 and GluR4 subunits and have a high Ca2+ permeability. The postsynaptic expression of GluR2 subunits may be continuously regulated by the presynaptic activity allowing for variations in the Ca 2+ permeability and physiological properties of the receptor.

Original languageEnglish
Pages (from-to)2981-2989
Number of pages9
JournalEuropean Journal of Neuroscience
Volume20
Issue number11
DOIs
StatePublished - Dec 1 2004

Fingerprint

AMPA Receptors
Cochlea
Neurons
Inner Auditory Hair Cells
Confocal Microscopy
Permeability
Western Blotting
Isoxazoles
alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
N-Methylaspartate
Synapses
Glycine
Nervous System
Hearing
Fluorescent Antibody Technique
Ions
Ligands

Keywords

  • AMPA receptors
  • Cochlea
  • Inner hair cells
  • Maturation of hearing
  • Synaptic maturation

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Transient Ca2+-permeable AMPA receptors in postnatal rat primary auditory neurons. / Eybalin, Michel; Caicedo-Vierkant, Diego A; Renard, Nicole; Ruel, Jérôme; Puel, Jean Luc.

In: European Journal of Neuroscience, Vol. 20, No. 11, 01.12.2004, p. 2981-2989.

Research output: Contribution to journalArticle

Eybalin, Michel ; Caicedo-Vierkant, Diego A ; Renard, Nicole ; Ruel, Jérôme ; Puel, Jean Luc. / Transient Ca2+-permeable AMPA receptors in postnatal rat primary auditory neurons. In: European Journal of Neuroscience. 2004 ; Vol. 20, No. 11. pp. 2981-2989.
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