HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 576/1/63    most recent jphysiol.2006.116467v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bonsacquet, J. Articles by Chabbert, C. Search for Related Content PubMed PubMed Citation Articles by Bonsacquet, J. Articles by Chabbert, C. Related Collections Neuroscience

¹ INSERM U583, Institut des Neurosciences de Montpellier, Groupe d'Etude des Désordres Vestibulaires, Hôpital Saint Eloi, BP74 103, 34091 Montpellier Cedex 5, France
² Institut de Génomique Fonctionnelle, Département de Pharmacologie Moléculaire, CNRS UMR5203, 141 Rue de la Cardonille, 34094 Montpellier Cedex 5, France

Glutamate is thought to be the main neurotransmitter at the synapse between the type I vestibular hair cell and its cognate calyx afferent. The present study was designed to identify the type of glutamate receptors involved in neurotransmission at this unusual synapse. Immunocytochemistry showed that AMPA GluR2, NMDA NR1 and NR2A/B subunits of the glutamate receptors were confined to the synaptic contact. We then examined the electrical activity at calyx terminals using direct electrophysiological recordings from intact dendritic terminals in explanted turtle posterior crista. We found that sodium-based action potentials support a background discharge that could be modulated by the mechanical stimulation of the hair bundle of the sensory cells. These activities were prevented by blocking both the mechano-electrical transduction channels and L-type voltage-gated Ca²⁺ channels involved in synaptic transmission. Although pharmacological analysis revealed that NMDA receptors could operate, our results show that AMPA receptors are mainly involved in synaptic neurotransmission. We conclude that although both AMPA and NMDA glutamate receptor subunits are present at the calyx synapse, only AMPA receptors appear to be involved in the synaptic transmission between the type I vestibular hair cell and the calyx afferent.

(Received 4 July 2006; accepted after revision 31 July 2006; first published online 3 August 2006)
Corresponding authors J. Bonsacquet & C. Chabbert: INSERM U583, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, BP74 103, 80 Rue Fliche, 34091 Montpellier Cedex 5 France. Email: jbonsacquet{at}univ-montp2.frcchabbert{at}univ-montp2.fr

This article has been cited by other articles:

				J. C. Holt, S. Chatlani, A. Lysakowski, and J. M. Goldberg Quantal and Nonquantal Transmission in Calyx-Bearing Fibers of the Turtle Posterior Crista J Neurophysiol, September 1, 2007; 98(3): 1083 - 1101. [Abstract] [Full Text] [PDF]

				A. Brugeaud, C. Travo, D. Dememes, M. Lenoir, J. Llorens, J.-L. Puel, and C. Chabbert Control of Hair Cell Excitability by Vestibular Primary Sensory Neurons J. Neurosci., March 28, 2007; 27(13): 3503 - 3511. [Abstract] [Full Text] [PDF]