Article
Cellular differences in cochlear nitrosylation after noise exposure and supplementary feeding with ascorbic acid in the guinea pig model
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Published: | August 10, 2015 |
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Objective: For the cochlea, there was a clear correlation between an intensive noise exposure and the loss of outer hair cells induced by nitrosactive stress. The aim of this study was to identify, if the cochlear pattern of nitrosylation can already be changed by moderate noise exposure and if ascorbic acid might influence the degree of nitrosylation.
Methods: Male guinea pigs with and without supplementary feeding with ascorbic acid for 1 week (n=6 ears each group) were exposed to 90 dB (SPL) for 1 h. The ears of treated and un-treated animals (n=6 ears each group) served as controls. At the end of the tests, the cochleae were removed, fixated and embedded in paraffin. Nitrosylation was identified on sections using a specific antibody (mouse, monoclonal, anti-nitrotyrosine, clone 1A6, upstate). Staining intensities were quantified for seven cochlear regions by computer.
Results: In untreated ears, the strongest staining intensities were identified in spiral ganglion cells and stria vascularis. This increase was still higher after supplementary feeding with ascorbic acid for 1 week. After noise-exposure for 1 h, again, an increase in staining intensity was seen in all cochlear regions. Combining noise exposure and supplementary feeding with ascorbic acid caused a clear reduction of nitrosylation.
Conclusion: Based on the clear increase in nitrosylation after moderate noise exposure or supplementary feeding with ascorbic acid, respectively, and based on a small increase after combination of both, different regulatory mechanisms must be assumed.