Investigating the Effects of Exposure to Continuous White Noise on SLC26A4 Gene Expression Levels in Male Rat Cochlea

Background and purpose: Irreversible damage to the inner ear is known as noise-induced hearing loss (NIHL). Exposure to excessive noise can affect the expression of genes in molecules involved in development of NIHL. SLC26A4 gene or PDS is responsible for causing both syndromic and non-syndromic deafness and is located at DFNB site. The aim of this study was to investigate the expression level of this gene due to continuous white noise exposure. Materials and methods: In this experimental study, 10 healthy male Wistar rats were divided into exposure group (n=6) and control group (n=4). Exposur group was exposed to continuous white noise (8hr/day, 6days, SPL=110±5dB) in noise chambers. Cochlear biopsy was done 1 hour (n=5) and 1 week (n=5) after exposure and then, RNA extraction, cDNA synthesis and Real-Time PCR analysis were done. In addition, histological analyzes were performed. Data analysis was done using One-Way ANOVA (95% CI diff.). Results: At both 1 hour and 1 week after exposure, the expression of SLC26A4 gene decreased significantly (P= 0.0005 and P= 0.0003, respectively). The fold changes compared to the control group (=1) were 0.0733 and 0.00712, respectively. Histological images illustrated serious damage to the cochlea. Conclusion: Sensorineural deafness will happen if exposure to intense noise continues and subsequently down-regulation of SLC26A4 in the cochlea occur during longer discontinuation and in case of expression level failure to return to its basal level.