Korean J Otorhinolaryngol-Head Neck Surg.  2014 Apr;57(4):226-232. 10.3342/kjorl-hns.2014.57.4.226.

The Protective Effect of Epigallocatechin-3-Gallate Against Gentamicin Vestibular Ototoxicity in Type I Vestibular Hair Cell of Guinea Pig

• Choi YH
• Lee SS
• Moon SJ
• Ahn BH
• Kim NG
• Jeong HS
• Park JS
• Cho HH
• Cho YB

• KMID: 1978142
• DOI: http://doi.org/10.3342/kjorl-hns.2014.57.4.226

Abstract

BACKGROUND AND OBJECTIVES
Gentamicin (GM) is well known for its vestibulotoxicity. There have been many reports about vestibulotoxicity, however, its mechanism is still unclear. So far, it is known that GM affects the voltage-dependent K+ current and nitric oxide (NO) production. Epigallocatechin-3-gallate (EGCG) is the major component of green tea and is known to have anti-oxidative and anti-toxic effect. This study was undertaken to investigate the protective effect of EGCG against gentamicin on vestibular hair cell (VHC). MATERIALS AND METHOD: White guinea pigs (200-250 g) were rapidly decapitated and the temporal bones were immediately removed. Under a dissecting microscope, the crista ampullaris was obtained. The dissociated VHCs were transferred into a recording chamber mounted onto an inverted microscope. Whole-cell membrane currents and potentials were recorded using standard patch-clamp techniques. In addition, measurements of NO production were obtained using the NO-sensitive dye, 4,5-diamino-fluorescein diacetate (DAF-2DA).
RESULTS
Type I VHCs Voltage-dependent K+ current was activated from low depolarizing stimulation. As the stimulation increased, higher current was detected. Voltage-dependent K+ current in type I VHCs was decreased when GM (200 microM) was administrated and GM effects of K+ current inhibition was significantly blocked by EGCG. Extracellular GM-induced an increase in DAF-2DA fluorescence, which thus indicates NO production in VHCs. Also, the GMinduced NO production was inhibited by EGCG.
CONCLUSION
GM inhibits voltage-dependent K+ current by releasing NO in isolated type I VHCs. EGCG blocks this inhibitory effects, suggesting a protective role on GM vestibulotoxicity.

Keyword

Epigallocatechin-3-gallate; Gentamicin; Vestibular hair cell; Vestibular toxicity

MeSH Terms

Animals
Fluorescence
Gentamicins*
Guinea Pigs*
Hair Cells, Vestibular*
Membranes
Nitric Oxide
Patch-Clamp Techniques
Semicircular Ducts
Tea
Temporal Bone
Gentamicins
Nitric Oxide
Tea