1997 Fiscal Year Final Research Report Summary
Regulatory mechonisms for pxocytosis
| Project/Area Number |
08457011
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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 | 一般 |
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| Research Field |
General physiology
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
OHMORI Harunori Kyoto-Univ.Faculty of Med.Dop.of Physiology Professor, 医学研究科, 教授 (30126015)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Synapse / Ca ion / GABA / MNTB / purkinje neuron |
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| Research Abstract |
(1) Potentiation of GABAergic postsynaptic currents in the Purkinje cells. Spontaneous inhibitory postsynaptic currents (IPSCs) and evoked IPSCs were recorded from cultured Purkinje cells of the rat. Size of these GABAergic IPSCs were increased after membrane depolarization of Purkinje cells. The increase was due to the increased GABA response in the postsynaptic membrane rather than the increased release of GABA presynapitcally, and was likely coupled with the activation of PLC through the increased intracellular Ca concentration and the IP3 induced Ca release.
(2) Postnatal development of phasic transmission in the clayx type synapse in the auditory relay nucleus of rat. Synaptic transmission in the medial nucleus of the trapezoid body (MNTB) of rats was analyzed in postnatal days of 4-13 (P4-P13) by applying the whole cell patch recording technique to brain slices. In P4-P6 animals, evoked EPSCs fluctuated extensively in amplitude and occurred in marked asynchrony, follwed by spontaneous EPSCs. With development of animals, the evoked EPSCs increased in amplitude, and the rise time became faster. In addition the synaptic transmission became phase-locked. The coefficient of variation (CV) of EPSC amplitude decreased with development (0.32(]SY.+-。[)0.03 for P4-P5 and 0.05(]SY.+-。[)0.01 for P9-P11). The amplitude of mEPSCs did not change throughout the postnatal days investigated (-30.2(]SY.+-。[)0.3 pA,at -70 mV). The CV was dependent on extracellular Ca2+ concentration ([Ca2+]o) and was reduced with the increase of [Ca2+]o, and this [Ca2+]o dependence was shifted towards lower [Ca2+]o with development. Direct patch recording of the presynaptic terminals demonstrated an increase in Ca2+ currents during these postnatal days. The phase-locked high-fidelity transmission in this synapse is achieved with development likely through the increase of Ca2+ currents and Ca2+ sensitivity of transmitter release mechanisms in the presynaptic terminal.
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