| Project/Area Number |
11671684
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Otorhinolaryngology
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| Research Institution | Ehime University |
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Principal Investigator |
GYO Kiyofumi Faculty of Medicine, Ehime University Professor, 医学部, 教授 (00108383)
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| Co-Investigator(Kenkyū-buntansha) |
HAKUBA Nobuhiro Faculty of Medicine, Ehime University Instructor, 医学部, 助手 (70304623)
SATO Hidemitsu Faculty of Medicine University hospital Ehime University Assistant Professor, 医学部・附属病院, 講師 (30187223)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥3,000,000 (Direct Cost: ¥3,000,000)
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| Keywords | transient cochlear ischemia / glutamate excitotoxicity / inner hair cell damage / delayed neuronal death / hypothermic therapy / glutamate transporter / sudden deafness / noise induced hearing loss / excitotoxicity / 蝸電図 / 内有毛細胞の変性 / 遅発性神経細胞障害 / 低体温 / 内耳虚血 / スナネズミ |
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| Research Abstract |
Glutamate is a neurotransmitter at the synapse of the primary afferent auditory neuron. When the inner ear is damaged, it is released excessively to the surroundings and aggravates hearing loss by working toxic to them. In the first experiment, we investigated the mechanisms of hearing loss due to transient cochlear ischemia in gerbils. The results showed that cochlear ischemia for 5 min causes delayed neuronal death of the inner hair cells probably due to excitotoxicity of glutamate. This was supported by remarkable increase of glutamate concentration in the perilymph. In the second experiment, effects of hypothermia were investigated in gerbils with cochlear ischemia for 15 min. Hypothermia was very effective to prevent hearing loss due to cochlear anoxia. Loss of the hair cells in hyopthermic group was very few compared to those in normothermic group. In the third experiment, role of glutamate in noise induced hearing loss was studied in mouse which genetically lacks GLAST, a glutamate transporter. In GLAST lacking mouse, hearing loss due to continuous exposure to loud noise was greater than that in wild mouse. As GLAST resorbs glutamate in the synaptic space, metabolism of glutamate in the synapse of the primary afferent auditory neuron is important to prevent hearing loss by noise.
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