Otoprotective Effect Of α-lipoic Acid On A/J Mice With Age-related Hearing Loss

Objective:Age-related hearing loss is one of the most common sensory diseases in the elderly population.Oxidative damage caused by reactive oxygen species plays an important role in the development of hearing loss.Antioxidants may enhance antioxidant defenses and may reduce cochlear cell damage,delay the occurrence of age-related convulsions.This study was to investigate the effect of antioxidant α-Lipoic acid on age-related hearing loss in A/J mice.Methods:The mouse pups at postnatal day 7(P7)were randomly distributed into no treatment,DMSO and α-lipoic acid+DMSO groups.In theα-lipoic acid+DMSO group,mice were intraperitoneally injected with α-lipoic acid,dissolved in DMSO(50μg/μl),at a dosage of 50μg/g body weight every other day.DMSO group received an equal amount of vehicle alone(1 μl of DMSO per gram of body weight).No intervention in the no treatment group.Dynamic detection of hearing changes in mice by auditory brainstem evoked response(ABR),hair cells were stained for F-actin with Alexa Fluor 488-labeled phalloidin.Histological analysis was used to observe changes in stria vascularis and spiral ganglion neurons.Real-time quantitative PCR and Western blotting monitors the expression of related genes.Results:With the increase of age,the ABR threshold of α-lipoic acid group was significantly lower than the no treatment group.Outer hair cells were stained with phalloidin,the results showed that the Outer hair cell loss of mice in the α-lipoic acid treatment group was significantly lower than that in the untreated group.Typical pathology on HE sections showed that compared with the untreated group,the mice in the α-lipoic acid treated group had thicker stria vascularis and a significantly lower rate of spiral ganglion neurons loss.Conclusion:Hearing impairment in A/J mice is attenuated by α-lipoic acid.The effects may be obtained by preserving OHC,SGN and stria vascularis in the cochleae.Antioxidant related pathways is likely involved in the otoprotection.The findings in this study may aid in understanding the mechanism of hearing loss in A/J mice.