Effect of 4 kHz Tone Exposure on the Guinea Pig Inner Ear: Relation in the Change of Cochlear Microphonics, Action Potential, Electrochemical Potential and K⁺ Ion Concentration Induced by Noise Exposure

Abstract

Using 110 male albino guinea pigs, and applying electrophysiological methods, we investigated the effects of 4 kHz tone at moderate sound pressure level on the inner ear at different exposure times (6, 12, 24 and 48 h). Longer than 12 h exposure to 4 kHz tone had a considerable effect on the hearing, inducing a decrease in the maximum output voltage of cochlear microphonics and an increase in the K⁺ concentration in the endolymph.

Down-regulation of otospiralin mRNA in response to acoustic stress in guinea pig

“…It has been recently reported that transient down-regulation of otospiralin in guinea pigs causes vestibular syndrome and deafness, the last being caused by a rapid and severe degeneration of the organ of Corti (Delprat et al, 2002). Because it is known that acoustic over-exposure lead to changes in perilymphatic and endolymphatic ion composition (Ikeda et al, 1988;Sugisawa et al, 1994;Li et al, 1997), down-regulation of otospiralin expression observed immediately after a noise stress could indicate that otospiralin is directly involved in ion homeostasis in inner ear structures and plays a key role in the maintenance of the ionic environment (Spicer and Schulte, 1991;Wang et al, 2002;Hirose and Liberman, 2003). So, otospiralin down regulation could be involved in changes in ion composition, during Fig.…”

A comparative study on the effect of pure-tone exposure of the guinea pig cochlea

“…In our previous studies, we investigated experimentally the effects of 4 kHz and 6 kHz sounds on the guinea pig inner ear [18,19] and observed changes in electrophysiological function. In particular, 6 kHz tone exposures had a strong effect on the endocochlear potential (EP) [4,14].…”