Otoprotective Effects of alpha-lipoic Acid on A/J Mice With Age-related Hearing Loss.

OBJECTIVE: A/J mice are a mouse model of age-related hearing loss (AHL) with progressive degeneration of outer hair cells (OHCs), spiral ganglion neurons (SGNs), and stria vascularis. This study was carried out to observe the otoprotective effects of alpha-lipoic acid on A/J mice. METHODS: A/J mouse pups at postnatal day 7 were randomly distributed into the untreated group, the dimethyl sulfoxide (DMSO) group, and the alpha-lipoic acid + DMSO group. alpha-lipoic acid was given to the mice intraperitoneally at a dosage of 50 mug/g body weight every other day. Time course auditory-evoked brainstem response (ABR) thresholds were tested. OHC loss was counted and the densities of SGNs and the width of stria vascularis were measured at 4 and 8 weeks of age. RESULTS: Measurement of the ABR thresholds revealed that hearing loss in A/J mice was attenuated by alpha-lipoic acid at age from 3 to 8 weeks. Moreover, preservation effects of OHCs, SGNs, and stria vascularis by alpha-lipoic acid were observed in the cochleae of A/J mice at 4 and 8 weeks of age. CONCLUSION: Hearing loss in A/J mice can be attenuated by alpha-lipoic acid. The otoprotective effects of alpha-lipoic acid on A/J mice may be obtained by preserving OHCs, SGNs, and stria vascularis in the cochleae. The oxidative damage related to gene mutations may be a potential target for AHL prevention and therapy.