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83rd Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

16.05. - 20.05.2012, Mainz

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Influence of dexamethason on nitric oxide (NO)-production in the guinea pig cochlea and hearing threshold shift after intratympanic application

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  • corresponding author presenting/speaker Kai Helling - University Medical Center of the Johannes Gutenberg - University Mainz, Mainz, Germany
  • Ilka Fischer - University Medical Center of the Johannes Gutenberg - University Mainz, Mainz, Germany
  • Jürgen Brieger - University Medical Center of the Johannes Gutenberg - University Mainz, Mainz, Germany
  • Wolf-Jürgen Mann - University Medical Center of the Johannes Gutenberg - University Mainz, Mainz, Germany
  • author Ulf-Rüdiger Heinrich - University Medical Center of the Johannes Gutenberg - University Mainz, Mainz, Germany

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. 83rd Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. Mainz, 16.-20.05.2012. Düsseldorf: German Medical Science GMS Publishing House; 2012. Doc12hno36

doi: 10.3205/12hno36, urn:nbn:de:0183-12hno362

Published: July 23, 2012

© 2012 Helling et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.

Outline

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Introduction:A cytoprotective effect of dexamethason might be based, for example, on the reduction of nitric oxide (NO)-concentration within the cochlea. The aim of the present study was to identify the interaction between the NO-production and changes in the hearing threshold after intratympanic application of dexamethason.

Methods: A volume of 0.1 mL dexamethason (8 mg) was injected into both middle ears of male guinea pigs (n = 24). Nine dexamethason-treated animals and nine saline-treated animals were exposed to 90dB for 1h. Twelve animals served as controls and five other animals were only exposed to noise. The hearing threshold was recorded for all animals. After preparation, the NO-production was determined by chemiluminescence in organ cultures of the organ of Corti and the lateral wall.

Results: In unexposed animals, the intratympanic application of dexamethason did not influence the NO-production or the hearing threshold over time. A noise exposure for 1h by 90dB resulted in a hearing loss and was attended by a triple NO-increase in the lateral wall and a twofold increase in the organ of Corti. When dexamethason or saline was given 14 h prior to noise exposure, the NO-production was reduced while the hearing threshold remained nearly unchanged. Seven days after noise exposure, the hearing threshold had recovered, independent of the increased NO-concentration in the lateral wall.

Conclusion: Despite published data in earlier studies demonstrating a correlation between hearing loss and increased NO-concentration, this study presents evidence for an additional time-delayed process in inner ear physiology.