The effects of salicylate on noise-induced hearing loss in the guinea pig

OBJECTIVE: To investigate the effects of salicylate on noise-induced hearing loss (NIHL) in guinea pigs. METHODS: The animals were allocated into four groups (salicylate + noise, saline + noise, noise only and salicylate only) and were exposed to a 4 kHz octave band noise at 105 dB SPL for 2 hours for 5 consecutive days. Dynamic changes of ABR thresholds evoked by clicks were monitored. After physiological examination, the cochleae were processed for the morphological examination by light microscopy. RESULTS: Mean thresholds of ABRs in the experimental group obtained on 5th day of the noise exposure was positively lower than the control groups (P < 0.05). The similar trends of ABR changes were found during other exposure days and after exposure, but the differences were not statistically significant. In the experimental group, there were 37.00 +/- 8.89 hair cell loses as assessed by nucleus staining, and 3.20 +/- 1.07 hair cells with nuclear deformation. The noise group had 74.11 +/- 10.28 hair cell loses and 10.43 +/- 9.71 hair cells with nuclear deformation, whereas the saline group had 63.60 +/- 7.97 hair cell loses and 20.80 +/- 15.48 hair cells with nuclear deformation. The difference between two groups was significant (P < 0.05). CONCLUSION: The results suggest that administration of salicylate facilitates the recovery of cochlear hearing and reduces damage to hair cells after noise exposure.