ABSTRACT
Objective In this study ,we investigated the apoptosis of hair cell in the cochlea of age -related hearing loss(AHL) generated by ENU mutagenesis ,and to study a pan caspase inhibitor (z-VAD -FMK) which is to protect the cochlea hair cells from hearing loss induced by age-related hearing loss(AHL) .Methods Through z-VAD-FMK intraperitoneal injection and round window membrane (RWM) drug were delivered into the Cdh23 nmf308 nmf/nmf mice 5(postnatal days 2 -32) inner ear .ResuIts The results showed that the nmf308 mice with progressive hair cell loss along a base to apex gradient with age-related hearing loss .The cochlear OHCs reduced from 5% ~10% at 1 month to 100% at 3 month in the basal region .Substantial amounts of TUNEL -positive OHCs nuclei appeared at 1 month age ,and activated caspase-3 labeling demonstrated that most OHCs appeared at 2 months age .These suggested that DNA single strand break was attributed primarily to apoptosis of cochlear le_sions ,whereas in the later stage of lesion ,the expansion led to activation of caspase-3 activity reduced with further progression of nuclear condensation in age-related hearing loss .ConcIusion The addition of a pan caspase inhibitor (z -VAD -FMK ) significantly protected the cochlea against the hair cell loss induced by apoptosis .Our study showed that aspase inhibitor ,Z-VAD-FMK appeared to play a prominent role in age-related hearing loss media_ted hair cell death loss induced by apoptosis .Our study showed that aspase inhibitor ,Z-VAD -FMK appeared to play a prominent role in age-related hearing loss mediated hair cell death .