Effect of Ebselen on Noise Induced Cochlear Damage

Park, Yong Ho; Lee, Yong Won; Park, Seok Won; Koo, Bon Seok; Kim, Yong Min; Rha, Ki Sang; Park, Chan Il

Abstract

BACKGROUND AND OBJECTIVES
With the advancement of modern civilization and mechanical development of society, the prevalence of noiseinduced hearing loss is increasing. There were some suggestions that noise-induced hearing loss may be reduced or prevented with antioxidant treatment. The purpose of this study is to evaluate the effect of ebselen as a free radical scavenger or antioxidant in noise-induced cochlear damage. MATERIALS AND METHOD: Thirty male Sprague Dawley rats (250-300 g) with normal auditory brainstem response (ABR) thresholds were exposed for 6 h to 115 dB SPL broad band noise. 10 mg/kg ebselen were injected intraperitoneally at 12 h before and 1h before noise exposure. After noise exposure, auditory brainstem response threshold shifts were evaluated. A study for iNOS and nitrotyrosine expressions in the cochlea was examined by immunohistochemical staining. RESULTS: After the noise exposure, auditory brainstem responses indicated that ebselen treatment reduced threshold shifts significantly. The expression of iNOS and nitrotyrosine were observed in hair cells, supporting cells of the organ of Corti, stria vascularis and spiral ganglion. The expression of iNOS and nitrotyrosine were lower in the ebselen treated group than in the non-treated group. CONCLUSION: Ebselen protects cochlea from noise by playing a role as a scavenger of reactive free radicals.