Effects of acute exposure to Al2O3-NPs (α and γ) and white noise and their combination on Cochlea structure and function in Wistar Rat

Abstract

Noise and combination-induced hearing loss is a common work-related disease among workers. The present research aimed to investigate the impact of independent and combined acute exposure to white noise plus Al2O3-NPs on changes in hearing and structural functions of the cochlea in rats. A total of 36 rats were randomly classified into six groups: Control, acute exposure to white noise, exposure to Al2O3-NPs (γ), exposure to noise plus Al2O3-NPs (γ ), exposure to Al2O3-NPs (α), and exposure to the combination of noise plus Al2O3-NPs (α). TTS and PTS were examined using DPOAE. Oxidative index (MDA, GSH-Px), gene expression (NOX3, TGF-ß, CYP1A1), protein expression (ß-Tubulin, Myosin VII), and histopathological changes were examined in the cochlea. The morphology of AL2O3-NPs was examined by TEM. The results of the DPOAE test, TTS in all groups, and the PTS in the groups exposed to noise, Al2O3-NPs (γ), and a combination of noise plus Al2O3-NPs increased significantly (p < 0.05). In exposure to white noise plus Al2O3-NPs, the MDA levels increased, the level of GSH-Px decreased, the expression percentage of ß-Tubulin and Myosin VII decreased, and the expression of NOX3, TGF-ß, and CYP1A1, (except for AL2O3-NPs (α) group) significantly increased (p < 0.05). Histopathological changes of the cochlea indicated damage in hair and ganglion cells which was higher in the combined exposures. The combined and independent exposure to white noise plus Al2O3-NPs damaged hair and ganglion cells for high-frequency perception, thereby affecting the function and structure of the cochlea and leading to TTS and PTS.