Correlation of SNR Value on DPOAE Examination with HSP70 Levels in Blood and HSP70 Expression in Cochlea of Noise Model Rattus norvegicus as an Indicator of Inner Ear Damage

Abstract

Background: Cellular stress caused by noise-induced hearing loss can be observed through the damage of cochlear hair cells, mechanically and metabolically. SNR value on the DPOAE examination assesses the sensory function of cochlear outer hair cells. HSP70 as marker of cellular stress can be identified from its levels in blood and its expression in the cochlea.Methods: Three groups of rats were used for the noise intervention: Group 1 was the control group, Group 2 had a noise exposure of 100 dB, and Group 3 received a noise exposure of 110 dB. DPOAE examination was then conducted, blood samples from rats’ tail were collected after a noise treatment, followed by the measurement of HSP70 levels by ELISA readings. Rats were terminated afterwards and immunohistochemical examination of the cochlear organ of Corti was performed to calculate the expression of HSP70. The data obtained were analyzed using SPSS.Results: A decrease occurred in the values of SNR and an increase occurred in HSP70 levels in blood along with its expression in the cochlea of noise model Rattus norvegicus, and there is a correlation between the three.Conclusion: The decrease in SNR values, increase in HSP70 levels in blood, and increase in HSP70 expression in the cochlear organ of Corti of Rattus norvegicus, proves that noise-induced hearing loss triggers the production of HSP70 as a cytoprotective agent in preventing inner ear damage.Keywords: DPOAE; Rattus norvegicus; NIHL; Heat Shock Protein 70