Evaluation of the Effect of Betahistine on Noise-Induced Hearing Loss Using Distortion Product Otoacoustic Emission and Scanning Electron Microscopy.

OBJECTIVE To evaluate the protective effect of betahistine on noise-induced hearing loss (NIHL) using scanning electron microscopy (SEM) and distortion product otoacoustic emission (DPOAE). MATERIALS AND METHODS A total of 8 adult albino guinea pigs were used in this study (study group: n=4 and control group: n=4). DPOAE measurements of both groups were performed before the procedure. Two hours before noise exposure, 0.9% NaCl solution was injected perorally to the control group and betahistine was administered through a peroral catheter to the study group. Both groups were then exposed to 105-dB sound pressure level (SPL) 4-kHz frequency-based narrow-band noise for 2 h per day for 5 days. DPOAE measurements were performed again on the 6th day and cochleae were dissected and examined by SEM on the 7(th) day. RESULTS Regarding the results of DPOAE, NIHL was observed in both groups on the 6th day (p<0.05). Loss, flattening, and fusion, which are findings of permanent hearing loss, were determined in the stereocilia of the inner and outer hair cells by SEM. These findings were evaluated as signs of permanent increase in the threshold. When DPOAE measurements and SEM results were evaluated in the study group, no significant difference was observed in NIHL compared with the control group (p>0.05). CONCLUSION In our study, it was observed that simultaneous administration of betahistine during noise had no protective effect on permanent increase in the threshold. However, further studies on noise and long-term use of betahistine can be performed.