Downregulation of GJB2 and SLC26A4 Genes Induced by Noise Exposure is Associated with Cochlear Damage

Abstract Noise can change the pattern of gene expression inducing sensorineural hearing impairment. There is no investigation on effects of noise frequency on the expression of GJB2 and SLC26A4 genes involved in congenital hearing impairment in cochlear tissue. This study investigated impacts of white and purple noise on gene expression and pathologic changes of cochlear tissue. In this study, 32 adult male Westar rats were selected and divided into experimental groups WN (animals exposed to white noise with a frequency range of 100-20000 Hz), PN (animals exposed to purple noise with a frequency range of 4-20 kHz) and control groups. All experimental groups were exposed to a sound pressure level of 118-120 dB for 8 hours per day. Cochlear tissue sampling was performed for tissue pathology studies, also RNA was extracted at 1 hour & 1 week after cessation of noise exposure. The results showed that Both white and purple noises caused permanent damage to the cortical, estrosilica systems of hair cells and ganglion of the hearing nerve. GJB2 and SLC26A4 were downregulated in both groups exposed with white and purple noise. However, differences are notably more significant in 1 weak post-exposure than 1 hour. Our Findings suggest GJB2 and SLC26A4 can be considered as biomarkers of response to noise frequency which is associated with the pathological response of cochlear tissue, leading to sensorineural hearing impairment. It would be suggested the demand for a more conventional approach to assessment of noise-induced hearing loss and subsequently the practice of hearing protection programs.