2007 Fiscal Year Final Research Report Summary
Tinnitus mechanisms analyzed in the inferior colliculus of the rat
| Project/Area Number |
17500228
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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 |
Nerve anatomy/Neuropathology
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| Research Institution | Shiga University of Medical Science |
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Principal Investigator |
KUDO Motoi Shiga University of Medical Science, School of Medicine, Professor (80108141)
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| Co-Investigator(Kenkyū-buntansha) |
AIMI Yoshinari Shiga University of Medical Science, School of Medicine, Associate Professor (20231756)
TAKI Kousuke Shiga University of Medical Science, School of Medicine, Assistant Professor (20359772)
RIQUIMAROUX Hiroshi Doshisha University, Graduate School of Ehgineering, Professor (90260207)
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| Project Period (FY) |
2005 – 2007
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| Keywords | anditory / inferior colliculus / tinnitus / P2X / nociceptin / rat / cerebral cortex / immunohistochemistry |
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| Research Abstract |
Tinnitus has been shown to be brain disorder. We have hypnotized that the cortico-collicular projection has a critical role in regulating the GABA/Glycine inhibitory system in auditory brain stem. First, we examined nociceptin system. Gene transfection using electroporation successfully visualizes nociceptin containing neurons in the inferior colliculus (IC) of the rat. Secondary we studied P2X systems, which is an ion-channel type receptor of ATP, are considered to be related to noxious stimuli. ATP-P2X neuro -transmission system has been well studied as an independent new system among several pain circuits. RT-PCR study revealed that homogenized brain issue of the rat IC contains P2X1 and P2X4 among 7 subfamilies of P2X. Then we made immunohistochmical study in the auditory brain stem. The results show that : (1) P2X1 positive fibers and their terminals are distributed entire IC, but the distribution is random not in the tonotopical order ; (2) A considerable number of the IC neurons are P2X4 positive, particularly in their cell membrane ; (3) Many, if not all, neurons in the medial nucleus of trapezoid body are P2X4 positive. Thus, our findings show that ATP-P2X neuronal transmission does exist in the central auditory system. It is highly possible that auditory signal processing is organized into multiple submodalities including noxious sound processing.
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