• Ulf-Rüdiger Heinrich, Sebastian Strieth, Irene Schmidtmann, Roland Stauber, and Kai Helling.
• Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany.
• Laryngoscope. 2016 Jan 1; 126 (1): E29-34.

Objectives/HypothesisDexamethasone is widely used in the treatment of various inner ear diseases. However, knowledge about its direct impact on glucocorticoid receptor (GR) expression is still limited.Study DesignProspective animal study in male guinea pigs.MethodsA therapeutic concentration of dexamethasone (8 mg/mL) or a physiological concentration of NaCl (0.9% solution) were intratympanically injected into the ears of guinea pigs (n = 10 in each case) 14 hours prior to 90 dB noise exposure (1 hour). Eighteen ears were exposed to noise only. Seven untreated ears were used as controls. Auditory brainstem responses were recorded prior to noise exposure or treatment and 2 hours thereafter. The cochleae were removed from the bullae, transferred to fixative, and embedded in paraffin. GR expression was identified immunohistochemically in the cochlea. Local staining intensities were quantified for seven regions by a computer.ResultsDexamethasone application significantly lowered noise-induced hearing loss. Statistically significant alterations in the average GR expression levels were identified exclusively in the spiral ligament. Comparing GR expression at the level of individual ear, numerous highly significant local associations were identified in the other six cochlear regions.ConclusionsThe intratympanic application of dexamethasone is suitable for supporting cochlear homeostasis under stress conditions. The lateral wall, mainly responsible for potassium recycling, seems to be the main target in glucocorticoid therapy.© 2015 The American Laryngological, Rhinological and Otological Society, Inc.

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