2001 Fiscal Year Final Research Report Summary
Development of a novel confocal microscopy and analysis of glia-neuron communication
| Project/Area Number |
10558107
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Biophysics
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KAWATO Suguru The University of Tokyo, Graduate School of Arts and Sciences, Professor, 大学院・総合文化研究科, 教授 (50169736)
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| Co-Investigator(Kenkyū-buntansha) |
TANAAMI Takeo Takeo Yokogawa Electric, Center for development project, Chief (Researcher), 係長(研究職)
KIMOTO Tetsuya The University of Tokyo, Graduate School of Arts and Sciences, Research Associate, 大学院・総合文化研究科, 助手 (60292843)
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| Project Period (FY) |
1998 – 2000
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| Keywords | confocal microscopy / neurosteroid / glia / neuron / Ca signal |
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| Research Abstract |
We constructed a real time scanning confocal microscopy system. This system enables gaining real-time serial confocal images by scanning the objective lens vertically. We carried out following experiments to evaluate its function. Upon mechanical stimulation using glass micropipette, Ca^<2+> signal was generated in a single astroglial cell. Radial propagation of Ca^<2+> wave across cultured astrocytes was observed. The Ca^<2+> wave reached a neuron in the fringe of astrocyte layer. Also Ca^<2+> signal from a mechanically stimulated neuron could elicit Ca^<2+> wave on the astrocyte layers. Thus, we indicated bi-derectional propagation of Ca^<2+> signals between cultured neurons and astrocytes with improved spatial resolution compared to conventional microscopy system. Next, we investigated a modulatory effect of a neurosteroid, pregnenolone sulfate (PREGS), on Ca^<2+> signal mediated by NMDA receptor in CA1 neurons of acute hippocampal slices after 20 min incubation with PREGS. Ca^<2+>-sensitive fluorescent dye Fura-2 was introduced in hippocampal neurons. Intracellular Ca^<2+> rise through NMDA receptor was doubled with 100 M PREGS, leading significant up-regulation of synaptic transmittion efficiency.
Also we are studying synthesis of neuroteroids and found that activity-dependent Ca^<2+> signals in hippocampal neurons could facilitate the synthesis of PREGS. Our results revealed a positive feedback system of neural transmittion; Ca^<2+> signal by neural activity induces the synthesis of PREGS from cholesterol→secreted PREGS enhances Ca^<2+> signal by NMDA receptors→facilitation of synaptic transmittion. we are currently proposing a novel concept of local synthesis and acute action of neurosteroids.
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[Publications] Shibuya K., Takata N., Hojo Y., Furukawa A., Kimoto T., Mukai H., Tanabe N., Enami T., Suzuki K., Yasumatsu N., Ishii H., Yamanaka M., Takahashi T., Hattori T., Kawato S.: "Hippocampal cytochrome P450s synthesize brain neurosteroids which are paracrine neuromodulators of synaptic signal transduction"Biochem. Biophys. Acta. (in press).
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