Synergistic effect of combined antioxidants on noise-induced acoustic trauma in adult guinea pigs. Audiological and histological study

Abstract

Introduction: Cochlear noise injury is considered one of the most debilitating diseases worldwide. Numerous drug trials have been made for complete protection from this acoustic trauma, unfortunately with little success. Recently, drug combination has showed promising effects in treating this trauma; however, this has to be further documented by in-depth researches. Aim of the work: To estimate the effect of combination of the antioxidants; vitamins A, C and E, plus magnesium (A, C, E+ Mg) in either protection or treatment of noise-induced cochlear injury in adult guinea pigs. Materials and methods: Twenty five guinea pigs were used in this study and were divided equally into five groups. Group I served as a control group. Group II administered the drug combination for 5 successive days. Group III exposed once to 120 dBSPL octave band noise for 5 successive hours. Group IV pre-treated with vitamins A, C, E+ Mg for 5 successive days prior to noise exposure. Group V first exposed to same noise injury, and then same drug combination was administered for 5 successive days, starting one day after noise exposure. Results: Noise exposure resulted in profound cochlear damage. Prophylactic administration of the drug combination showed partial protection of the cochlea as detected audiologically and histologically. In contrast, significant improvement of both function and structure of the cochlea was revealed with post-treatment 1 day after noise- induced cochlear damage. Conclusion: Delayed treatment by this combination of drugs (vitamins A, C, E+ Mg) proved to be effective even if started one day after noise exposure. However, drug combination used as prophylactic treatment was not as effective.