Animal model for studying inner ear mechanism of aging

• Project/Area Number: 12671674
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Otorhinolaryngology
• Research Institution: MIYAZAKI MEDICAL COLLEGE
• Principal Investigator: TORIHARA Koji Miyazaki Med Coll., Dept. Otorhinolaryngology, Assistant researcher, 医学部, 助手 (30264386)
• Co-Investigator(Kenkyū-buntansha): 松田 圭二 宮崎医科大学, 医学部, 助手 (40253835)
• Project Period (FY): 2000 – 2001
• Project Status: Completed (Fiscal Year 2001)
• Budget Amount: ¥1,000,000 (Direct Cost: ¥1,000,000); Fiscal Year 2001: ¥1,000,000 (Direct Cost: ¥1,000,000)
• Keywords: Klotho mice / potassium dencity / EP / Presbyacusis / aging / 老化 / 内耳形態

Research Abstract

Mice deficient in Klotho gene expression exhibit a syndrome resembling premature human aging. To determine whether mouse homozygotes for the kl mutation (kll kl) show hearing dysfunction, histochemical study by the PAS reaction with light (LM) and electon microscopy (EM), and physiological study by measurement of the endocochleal static potential (EP) and potassium density in endolymph. The substances with PAS positive raction are found in large amounts in the stria vascularis with LM study. Especially, the endothelial cell and the basement membrane of capillaries in stria vascularis with EM study. The both of EM PAS reactions with the PA-TCH-SP method and the PA-SP method are the same reaction. The existence of PAS reactive substances might be associated with vascular endothelial dysfunction. We demonstrate that the EP of Klotho mice is significantly smaller (80.9 ± 7.2mV) than the EP of wild-type mice (96.9 ± 7.7mV), however, potassium densities in endolymph between klotho mice (209.7 ± 20.4mM) and wild-type mice (207.2 ± 26.2mM) are almost equivalent. These results suggest a decrease in EP is associated with stria vascularis dysfunction. The process of presbyacusis might be a reflection of stria vascularis dysfunction caused by aging.