Changes in microRNA Expression in the Cochlear Nucleus and Inferior Colliculus after Acute Noise-Induced Hearing Loss.

Sohyeon Park,Jun Ho Lee,Moo Kyun Park,Byeong-Gon Kim,Seung Ha Oh,Seung Hee Han,Myung-Whan Suh

doi:10.3390/ijms21228792

Abstract

Noise-induced hearing loss (NIHL) can lead to secondary changes that induce neural plasticity in the central auditory pathway. These changes include decreases in the number of synapses, the degeneration of auditory nerve fibers, and reorganization of the cochlear nucleus (CN) and inferior colliculus (IC) in the brain. This study investigated the role of microRNAs (miRNAs) in the neural plasticity of the central auditory pathway after acute NIHL. Male Sprague–Dawley rats were exposed to white band noise at 115 dB for 2 h, and the auditory brainstem response (ABR) and morphology of the organ of Corti were evaluated on days 1 and 3. Following noise exposure, the ABR threshold shift was significantly smaller in the day 3 group, while wave II amplitudes were significantly larger in the day 3 group compared to the day 1 group. The organ of Corti on the basal turn showed evidence of damage and the number of surviving outer hair cells was significantly lower in the basal and middle turn areas of the hearing loss groups relative to controls. Five and three candidate miRNAs for each CN and IC were selected based on microarray analysis and quantitative reverse transcription PCR (RT-qPCR). The data confirmed that even short-term acoustic stimulation can lead to changes in neuroplasticity. Further studies are needed to validate the role of these candidate miRNAs. Such miRNAs may be used in the early diagnosis and treatment of neural plasticity of the central auditory pathway after acute NIHL.

Highlights

According to the World Health Organization, 466 million people—more than 5% of the world’s population—are affected by hearing loss [1]
Our noise-control model (n = 4) showed that the auditory brainstem response (ABR) threshold started to decrease at day 1 after the noise exposure
Our results demonstrated that even short-term acoustic stimulation can cause changes in miRNA expression in the cochlear nucleus (CN) and inferior colliculus (IC), and that these changes may induce plasticity in the central auditory pathway

Summary

Introduction

According to the World Health Organization, 466 million people—more than 5% of the world’s population—are affected by hearing loss [1]. Loss of hearing makes communication difficult and can lead to psychosocial problems, such as depression and feelings of loneliness [2]. NIHL is a type of acquired hearing loss that is due to a sudden excessively loud sound or continuous moderately loud sounds. Depending on the duration and intensity of the sounds, hearing loss can be temporary or permanent [3]. Threshold sensitivity loss after exposure to a loud noise can be recovered to baseline levels after a few hours to weeks and that is called temporary threshold shift (TTS). Permanent threshold shift (PTS) occurs when the noise is too loud to recover to its baseline level or the noise takes place repeatedly or continuously, impeding recovery

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