Otoprotective Effects Of Mouse Nerve Growth Factor In DBA/2J Mice With Early-onset Age-related Hearing Loss

DBA/2J mice are inbred strain widely used in hearing research, which displayed progressive hair cell loss and degeneration of spiral ganglion neurons(SGNs) characterized by age-related hearing loss (AHL). Mouse nerve growth factor (mNGF) is the most common exogenous nerve growth factor (NGF), which has been studied extensively for promoting neuronal survival and growth. To determine whether mNGF can ameliorate AHL in DBA/2J mice, mNGF was given to the DBA/2J mice by intramuscular injection every day from 1 week after birth to the 9th week. In comparision with vehicle groups, mNGF groups decrease the auditory evoked brain stem response (ABR) thresholds and increase the distortion product oto-acoustic emission (DPOAE) amplitudes, prevent hair cell loss, inhibit apoptosis of spiral ganglion neurons(SGNs) and degenerate of stria vascularis(SV).The Bak-dependent mitochondrial pathway was detected to confirm the mechanism of mNGF protection in the hearing loss of DBA/2J mice. These results demonstrate that mNGF can act as an otoprotectant in DBA/2J mice model for the early intervention of AHL and become of great value to clinical application.