Influence of noise exposure on antioxidant system and TEOAEs in rabbits

Abstract

Noise exposure may cause hearing loss. The precise mechanism leading to cochlear damage in acoustic trauma is not known. Eight rabbits were used in this study. Transient evoked otoacoustic emissions (TEOAEs) were recorded in all animals and blood malondialdehyde (MDA) and glutathione (GSH) levels were determined. All rabbits were then exposed to 100 dB SPL broadband noise for 1 h. TEOAEs were recorded again and blood MDA and GSH levels determined following noise exposure. The reproducibility scores of the TEOAE measurements were found to be significantly lower (P < 0.01), whereas the amplitudes and signal-to-noise values of emissions decreased (P > 0.01) in rabbits exposed to noise. The TEOAE energies were poor at 4 kHz. During this threshold shift, GSH blood levels decreased and MDA levels increased, indicating that there is a close relationship between noise-induced hearing loss and the antioxidant system. These findings indicate that TEOAE recording is an excellent test for detecting effects of noise on hearing.