Cochlear histological changes after noise exposure: effects of melatonin and resveratrol in an experimental model

OBJECTIVE: To assess cochlear histological changes and the otoprotective effects of melatonin and resveratrol in Wistar rats exposed to high sound pressure levels. METHODS: This was a prospective, longitudinal, in vivo experimental study with heterogeneous male Wistar rats. The animals were divided into groups and treated with or without 10 mg/day of melatonin or resveratrol administered intraperitoneally for 14 days. They were then exposed to or not exposed to white noise (4 kHz; 100 ± 3 dB) for 8 h daily for 10-days. Histological analyses were performed on the spiral ganglion, spiral limbus, spiral ligament, and stria vascularis on days 15 (D15) and 30 (D30), after euthanasia. The data were analyzed by ANOVA. RESULTS: The animals in the control group had a higher number of cells in the analyzed cochlear structures than the noise-exposed group. Treatment with melatonin or resveratrol prevented the noise-induced reduction in the number of neurons in the spiral ganglion, maintaining cell counts similar to those in the control group. Resveratrol was also effective in preserving the spiral ligament. CONCLUSION: The findings suggest that the preventive administration of antioxidants may be an effective strategy in mitigating noise-induced hearing loss, reinforcing the therapeutic potential of these compounds in preventing hearing impairment. LEVEL OF EVIDENCE: V.