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Protective Effects of N-Acetyl-L-Cysteine on the Density of Spiral Ganglion Cells and Histological Changes Induced by Continuous Noise Exposure in Rats
Hashemi Habybabady, Raheleh; Mortazavi, Seyed Bagher; Khavanin, Ali; Mirzaei, Ramazan; Arab, Mohammad Reza; Mesbahzadeh, Behzad; Hoseini, Mehran & Mohammadi, Mahdi
Abstract
Background: Noise exposure causes loss of cochlea hair cells, leading to permanent
sensorineural hearing loss, and initiates pathological changes to the bipolar primary auditory
neurons (ANs). This study focuses on the effects of N-acetyl-l-cysteine (NAC) in protecting the
density of spiral ganglion cells and in histological changes induced by continuous noise exposure in
rats.
Methods: Twenty-four male Wistar rats were randomly allocated into four experimental
groups to receive NAC, saline, noise, or both noise and NAC. Noise exposure continued for ten
days. Saline and NAC were injected daily during the noise exposure, and 2 days before and after the
noise exposure. Evaluation of cochlear histopathology and the density of spiral ganglion cells was
performed 21 days after exposure.
Results: In the animals exposed to noise, a reduction in the density of spiral ganglion
cells was evident in both the basal and middle turns of the cochlea. This improved on receiving
NAC treatment (P = 0.046). In the histopathology evaluation, some histological changes, such as
disorganised architecture of the outer hair and supporting cells and a slightly thickened basilar
membrane, were found in the basal turns in the noise group.
Conclusion: NAC offered partial protection against noise exposure by improving the
density of spiral ganglion cells and reducing morphological changes.
Keywords
N-acetyl-l-cysteine; noise; cochlea; histology; spiral ganglion cells; hearing loss
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