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Expression of Caveolin-1 in the Differentiated Vestibular Cell Line (UB/UE-1) after Gentamicin Toxicity
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Byung Han Cho, Kyu Sung Kim, Min Wook Kim, Min Sun Kim, Byung Rim Park
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J Korean Bal Soc. 2005;4(2):243-249.
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 Abstract
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- Background
and Objectives: The caveolin is known as a mediator of cell death or survival of injured cell and inhibitor of various signaling pathways. We examined expression of caveolin-1 involved by protein kinase A(PKA) signaling pathway in the differentiated mouse vestibular cell line(UB/UE-1) after gentamicin toxicity.
Materials and Method: We observed caveolae in the vestibular hair cell of healthy guinea pig through electron microscope. UB/UE-1 cells were cultured at 95% CO2, 5% O2, 33℃ for 2days and at 95% CO2, 5% O2, 39℃ for 24 hours for differentiation. Cells were treated with 1 mM of gentamicin, 0.02 mM H89 (PKA inhibitor), and then incubated for 24 hours. Caveolin-1 expression was examined by western blot and PKA activity by PepTagⓇ assay.
Results
Caveolae were observed in the vestibular hair cell of healthy guinea pig by electron microscope. Caveolin-1 was expressed spontaneously in differentiated UB/UE-1 cells and increased after gentamicin treatment. PKA is overactivated by gentamicin treatment. The gentamicin induced caveolin-1 expression and PKA overactivation was inhibited by H89.
Conclusion
Our results indicate that gentamicin induced caveolin-1 expression is mediated by PKA signaling pathway. We conclude that the caveolae/caveolin through a PKA signaling pathway is the important mechanism of gentamicin induced ototoxicity.
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Comparison of Vestibule-ocular Reflex of Eccentric Rotation with Centric Rotation in Normal Subjects
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Byung Han Cho, Seung Yeun Jang, Ho Suk Choi, Seung Chul Lee, Kyu Sung Kim
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J Korean Bal Soc. 2004;3(2):351-335.
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Abstract
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- Background
and Objectives : Conventional vestibular rotation testing with the head centered on the axis stimulates the semicircular canals evoking compensatory eye movements. By placing subjects off from the axis of rotation, the otolithic organ may also be simultaneously stimulated by additional linear acceleration forces. In the present study, we compared the rotation with subjects placed on axis to those placed in an eccentric position.
Materials and Method : In the eccentric rotation, the head of subject was facing outward and placed eccentrically for 33cm on naso-occipital axis. Slow harmonic acceleration test and velocity step test were performed.
Results
: The sinusoidal eccentric rotation at 0.32, 0.64 Hz produced a significantly higher vestibulo-ocular reflex gain than did on axis rotation. In velocity step test, initial slow component velocity was significantly higher in eccentric rotation than in centric rotation.
Conclusion
: These finding suggest that the gain enhancement due to eccentric rotation is a result of tangentiallinear acceleration, probably sensed by the otolithic organ. This study raises the possibility of using eccentric rotation for the diagnosis of the patients with otolithic dysfunction.
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