ion transport and its regulation in the inner ear (endolymphatic sac, stria vascularis)

Research Project

Project/Area Number	17K11330
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Otorhinolaryngology
Research Institution	Kagawa University
Principal Investigator	Miyashita Takenori 香川大学, 医学部, 准教授 (60363214)
Project Period (FY)	2017-04-01 – 2020-03-31
Project Status	Completed (Fiscal Year 2019)
Budget Amount *help	¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000) Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000) Fiscal Year 2018: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000) Fiscal Year 2017: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Keywords	内耳 / イオン輸送 / 内リンパ嚢 / 血管条 / RT-PCR / リアルタイムPCR / メニエール病 / 内リンパ水腫 / イメージング / mRNA / LCM / ホルモン
Outline of Final Research Achievements	The endolymphatic sac in the inner ear is thought to absorb endolymph. Endolymphatic sac dysfunction causes an excess of endolymph, a pathological condition in Meniere's disease. A low-salt diet is an effective treatment for Meniere's disease. We succeeded in extracting and quantifying a small amount of mRNA from the endolymphatic sac epithelium and succeeded in analyzing each portion of the endolymphatic sac. The expression of Na+/K+-ATPase, epithelial Na channel, and thiazide-sensitive Na-Cl cotransporter were significantly higher in the intermediate portion of the endolymphatic sac in the low-salt diet model animals than high-salt diet model animals. It is suggested that the low-salt diet may improve endolymphatic hydrops by activating endolymphatic absorption through activating Na transport in the endolymphatic sac, especially in the intermediate portion of the endolymphatic sac.
Academic Significance and Societal Importance of the Research Achievements	減塩食・高塩食モデル動物を用いた本研究から、減塩食は内リンパ嚢における内リンパの吸収を促進し、内リンパ水腫を改善する可能性があることが示唆された。内リンパ水腫を病態とするメニエール病の治療の一つとして減塩食が勧められることを、動物モデルでも確認し、これまで臨床研究で想像されていた、内リンパ水腫の調節機構の一つを解明することができた。今後、さらに研究を進めることで、内リンパ水腫を病態とするメニエール病などの疾患の経験的治療の根拠を補強し、新たな治療法開発に結び付く可能性がある。