Cochlear electrophysiology and histopathology of rats exposed to intratympanic silica nanoparticles

Toxic effects of silica nanoparticle of rats exposed intratympanically for 7 days were investigated using brainstem auditory evoked potential and distortion product otoacoustic emission techniques. The histopathological changes were evaluated with light microscopy and field emission-scanning electron microscopy were demonstrated in cochleas using based energy-dispersive X-ray spectroscopy. The reduction in the amplitude and prolongation at the peak latency and interpeak latencies of brainstem auditory evoked potential were observed. Silica nanoparticles significantly reduced distortion product otoacoustic emission amplitude in the 2, 3 and 4 kHz frequencies. In the light microscopic evaluation, the samples obtained from the experimental group showed a significant loss of hair cells. Field emission scanning electron microscope analysis of experimental group showed considerable hair cell damage compared to control group. The findings of this study show that intratympanic administration of silica nanoparticles may lead to hearing impairment by causing structural changes in cochlear hair cells.