Applying neurotrophins to the round window rescues auditory function and reduces inner hair cell synaptopathy after noise-induced hearing loss

Abstract

Hypothesis: Applying neurotrophins to the round window immediately after a single noise exposure will prevent noiseinduced hidden hearing loss. Background: Loud noise can eliminate neural connections between inner hair cells and their afferent neurons (thereby diminishing sound perception) without causing a detectable change on audiogram. This phenomenon is termed hidden hearing loss. Methods: Guinea pigs were exposed for 2 hours to 4 to 8 kHz noise at either 95 or 105 dB SPL. Immediately afterward a 4 ml bolus of neurotrophins (brain-derived neurotrophic factor 1mg/ml, and neurotrophin-3 1mg/ml) was delivered to the round window of one ear, and saline to the other. Auditory brainstem respon..