Electrophysiological evaluation of the effects of grape seed oil and dexamethasone on the cochlea of the rats exposed to acoustic trauma

The aim of this study is to search whether using grape seed oil orally is more effective than intraperitoneal dexamethasone application after acoustic trauma, by distortion product otoacoustic emissions (DPOAE) test. Twenty-four female Sprague-Dawley rats (mean age 12 months, and mean weight 250 g) were included in this study. Autoscopic examinations and DPOAE tests of rats were performed under general anesthesia and their hearing thresholds were measured. Then acoustic trauma was created by exposing to the white noise (103 dB SPL intensity) in free field for 12 hours. After acoustic trauma rats were divided three groups. The first group was given grape seed oil by gavage (150 mg per kg/ day) at second hours after trauma, and for following 21 days. The second group was administered dexamethasone (125 µg per kg/ day) intraperitoneally for 14 days. The third group was selected as controls and given no medication. During the study one rat from each second and third groups were ex.DPOAE measurements of the rats were made total of four times ( before acoustic trauma, 1st, 7th and 21st day, respectively.) When the groups were compared to each other, it was not detected any statistically significant difference among the DPOAE values measured before acoustic trauma and at 1st day (p>0.05). According to the measurements made on 7th and 21st days, the values of the first (given grape seed oil) and control groups were detected significantly lower than the values of 1st day (p<0,05). In the measurements made after acoustic trauma, no significant change was observed in the dexamethasone group (p>0,05). DPOAE values of the dexamethasone group measured on 7th and 21st days were found significantly higher than the values of the first and control groups (p<0,05). In conclusion, our findings suggest that grape seed oil has not protective effect on cochlear damage after acoustic trauma even at these given doses and duration but dexamethasone may have a protective effect partially.