Early Postnatal NT-3 Gene Delivery Enhances Hearing Acquisition in the Developmental Period.

Objectives/hypothesis: The purpose of this study was to investigate the effect of early postnatal neurotrophin-3 (NT3) support on hearing acquisition.

Study Design: A prospective experimental animal study.

Methods: Adenoviral (Ad) vectors expressing green fluorescence protein (GFP) alone or in combination with NT3 were injected into the scala tympani through the round window of 5-postnatal-day-old (P5) rats. Changes in NT3 mRNA level, hearing thresholds, and morphological studies were done after the viral vector injection.

Results: NT3 mRNA was significantly increased in the Ad-GFP-NT3 group compared to the normal-developmental group and Ad-GFP alone group. GFP was widely expressed in the cochlea such as in the hair cells, supporting cell area, and spiral ganglion neurons. Auditory brainstem response thresholds were significantly lower in the Ad-GFP-NT3 group compared to the normal-developmental group and Ad-GFP alone group at P15.

Conclusions: These results show that early postnatal NT3 overexpression may accelerate the acquisition of hearing in rats.

Level Of Evidence: NA Laryngoscope, 126:E379-E385, 2016.