Auditory and Vestibular Systems

Excitotoxicity and repair of cochlear synapses after noise-trauma induced hearing loss

Puel, Jean-Luc1,2; Ruel, Jérôme1; d'Aldin, Christine Gervais1; Pujol, Rémy1

Author Information

1INSERM–U. 254 et Université Montpellier I, Laboratoire de Neurobiologie de l'Audition, CHU Hôpital St. Charles, 34295 Montpellier cedex 5, France.

2Corresponding Author: Jean-Luc Puel

ACKNOWLEDGEMENTS: The authors wish to thank G. Humbert for efficient technical assistance and J. L. Pasquier for art work. Special thanks to Prof. R. P. Bobbin who initiated part of the physiological experiments. TEM investiga-tions were performed at C.R.I.C. “Centre Régional d'Imagerie Cellulaire de Montpellier” with the technical support of F. Tribillac and P. Paulet.

Website publication 10 June 1998

Received 3 April 1998; accepted 16 April 1998

NeuroReport 9(9):p 2109-2114, June 22, 1998.

Abstract

GUINEA-PIGS were exposed to a traumatic sound inducing up to Θ dB hearing loss. Beside the well described mechanical damage to outer hair cells, a total disruption of inner hair cell (IHC)–auditory nerve synapses was acutely observed within the traumatized area. To test the hypothesis that synaptic damage is due to an excessive release of glutamate by the IHCs, we examined the protective effect of the glutamate antagonist kynurenate on noise-induced hearing loss. The high degree of protection observed with kynurenate attests that dendritic damage is an important component in noise-induced hearing loss. Moreover, we demonstrate that a synaptic repair mechanism occurring within the first few days post-exposure is partly responsible for the recovery of temporary threshold shifts after an acoustic trauma.

© Lippincott-Raven Publishers.

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