Specific Influences of Early Acoustic Environments on Cochlear Hair Cells in Postnatal Mice.

Aoshuang Chang,Hongzheng Zhang,Wenlu Pan,Jie Tang,Peng Chen,Shasha Guo,Cuixian Li,Nana Xu

doi:10.1155/2018/5616930

Abstract

The auditory function develops and matures after birth in many mammalian species. After hearing onset, environmental sounds exert profound and long-term effects on auditory functions. However, the effects of the acoustic environment on the functional development of the peripheral auditory system, especially the cochlear sensory hair cells, are still unclear. In the present study, we exposed mouse pups to frequency-enriched acoustic environments in postnatal days 0–14. The results indicated that the acoustic environment significantly decreased the threshold of the auditory brainstem response in a frequency-specific manner. Compared with controls, no difference was found in the number and alignment of inner and outer hair cells or in the length of hair bundles after acoustic overstimulation. The expression and function of prestin, the motor protein of outer hair cells (OHCs), were specifically increased in OHCs activated by acoustic stimulation at postnatal days 7–11. We analyzed the postnatal maturation of ribbon synapses in the hair cell areas. After acoustic stimulation, the number of ribbon synapses was closer to the mature stage than to the controls. Taken together, these data indicate that early acoustic exposure could promote the functional maturation of cochlear hair cells and the development of hearing.

Highlights

Acoustic information carried by sound waves is transduced into electric signals by cochlear hair cells (HCs) and transmitted to spiral ganglion neurons (SGNs) and central auditory nuclei
As all input signals for neural activity originated from HCs, which are the peripheral sensory cells of the auditory system, any inference on HCs may have a major effect on the development of the auditory function
During the first few days after birth, no auditory brainstem responses (ABRs) was detectable until P7

Summary

Introduction

Acoustic information carried by sound waves is transduced into electric signals by cochlear hair cells (HCs) and transmitted to spiral ganglion neurons (SGNs) and central auditory nuclei. During a brief postnatal period around the hearing onset, the structure and function of the cochlea and central auditory system undergo marked changes [3,4,5]. Exposure to an acoustic environment can quickly change the sensitivity and frequency selectivity of neurons at many levels along the auditory pathway [3, 5]. Exposure to environmental sounds modulates the innervations and response properties of neurons in the auditory pathway [5,6,7,8,9]. Little is known about whether early experience influences the development of cochlear HCs

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