1988 Fiscal Year Final Research Report Summary
Analysis in the action of endogenous substances in spinal ventral horn upon motoneurones.
| Project/Area Number |
62480106
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Neurophysiology and muscle physiology
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| Research Institution | Kyoto University |
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Principal Investigator |
TOMOYUKI Takahashi Kyoto University, Faculty of Medicine, 医学部, 講師 (40092415)
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| Project Period (FY) |
1987 – 1989
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| Keywords | motoneurones / slices / IPSCs / serotonin / patch-clamp / glycine / inward rectifier / spinal cord / 自発性微小シナプス電流 |
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| Research Abstract |
In order to investigate upon the action of endogenous substances in the ventral horn of spinal cord, a new technique was developed to record from motoneurones by using patch clamp methods. Motoneurones were visualized under nomarski optics in slices of rat spinal cord prepared in the thickness of about 100 um. Connectives covering plasma membrane of motoneurones were removed by applying jet stream locally to facilitate gigaohm seal. Whole-cell as well as outside-out recordings were subsequently made. First the properties of inhibitory postsynaptic currents (IPSCs) were compared with those of currents induced by glycine. They were indistinguishable in terms of reversal potentials and receptor desensitization . The kinetics of the single channel currents induced by glycine were almost identical with those of the IPSCs. These results indicate that glycine is most likely to mediate IPSCs. It was estimated that a single IPSC quantum involve only 20 molecules of glycine receptors. Second the action of serotonin upon motoneurones were analysed. Serotonin produced excitatory action by activating the in type inward rectifier of motoneurones. This was deduced by the similarities of serotonin-current and inward rectifier in terms of actions of Cs, Ba as well as of the current-voltage relation. It is concluded that serotonin released from nerve terminals of descending neurones would serve to maintain excitability of motoneurones.
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