Protection Against Gentamicin Ototoxicity by the Administration of Dexamethasone on the Cochlear Round Window Membrane / 听力学及言语疾病杂志

ABSTRACT

Objective To investigate the protective effects of round window membrane administration of dex-amethasone(Dex) on ototoxicity induced by gentamicin(GM) .Methods Sixty guinea pigs with normal hearing were randomly divided into four groups ,①GM grouptreated with gentamicin by 120 mg · kg -1 · d-1 for 10 days;②GM -S-Dex grouptreated as the GM group and dexamethasone by intraperitoneal injection 2 .5 mg · kg -1 · d-1 for 10 days;③GM -T -Dex grouptreated as the GM group and dexamethasone by round window administration on right ear ;④NS -T -Dex grouptreated with sodium chloride by 120 mg · kg -1 · d-1 for 10 days and with dex-amethasone topically as GM -T -Dex group .The auditory brainstem response (ABR) was respectively measured before the treatment and on day 1 ,day 10 after the treatment .After the treatment ,animals were killed instantly and the middle ear mucosa and the Corti's organ were observed with SEM .Results There was no change of ABR threshold in NS -T -Dex group on day 10 after the treatment ,whereas ABR thresholds in the other groups were elevated and GM group was the most significant .The massive outer hair cells loss was observed in GM group while the loss in GM -T -Dex group and GM -S-Dex group was trivial .The middle ear mucosa was normal and no inflammation was found in any of the groups .Conclusion The results indicated that round window administration of dexamethasone had protective effects aganist the gentamicin -induced hearing loss .