| Project/Area Number |
14370594
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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 |
Functional basic dentistry
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| Research Institution | OKAYAMA UNIVERSITY |
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Principal Investigator |
MATSUO Ryuji OKAYAMA UNIVERSITY, Graduate School of Medicine and Dentistry, Professor, 大学院・医歯学総合研究科, 教授 (30157268)
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| Co-Investigator(Kenkyū-buntansha) |
MITOH Yoshihiro OKAYAMA UNIVERSITY, Graduate School of Medicine and Dentistry, Assistant, 大学院・医歯学総合研究科, 助手 (20240872)
FUNAHASHI Makoto OKAYAMA UNIVERSITY, Graduate School of Medicine and Dentistry, Assistant, 大学院・医歯学総合研究科, 助手 (80221555)
KOBASHI Motoi OKAYAMA UNIVERSITY, Graduate School of Medicine and Dentistry, Associate Professor, 大学院・医歯学総合研究科, 助教授 (80161967)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥9,600,000 (Direct Cost: ¥9,600,000)
Fiscal Year 2003: ¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 2002: ¥5,500,000 (Direct Cost: ¥5,500,000)
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| Keywords | superior salivatory nucleus / patch clamp / synaptic current / glutamate receptor / GABA receptor / glycine receptor |
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| Research Abstract |
The superior salivatory (SS) nucleus contains parasympathetic preganglionic neurons innervating the submandibular and sublingual salivary glands and those innervating the anterior part of the tongue. To evaluate mechanisms of impulse formation, we analyzed postsynaptic currents of the SS neurons. The SS neurons were labeled by injection of fluorescent tracers into the peripheral course of the neurons in neonatal Wistar rats. Two days after the injection, the brainstem was sliced and whole-cell patch-clamp recordings were obtained from the labeled neurons. The whole-cell postsynaptic currents were evoked by electrical stimulation applied near the recording cell. The following results were obtained. 1) The SS neurons innervating the different targets scattered and intermingled in the lateral reticular formation of the medulla oblongata, which have 3-4 main dendrites that extended dorso-ventrally about 700 um. 2) The whole-cell currents were antagonized by bicuculline, strychnine, CPP, and CNQX, suggesting that major components of the postsynaptic currents are mediated by GABA_<A->, glycine-, NMDA-, and non-NMDA-receptors. 3) In the SS neurons for the salivary glands, the ratio of the NMDA component to the total excitatory postsynaptic currents was larger than that of the non-NMDA component, and the GABA_A component was larger than the glycine component. 4) Bath application of baclofen, GABA_B-receptor-agonist, reversibly and dose-dependently reduced the amplitude of the inhibitory postsynaptic currents in some neurons. No changes in the input resistance of the postsynaptic membrane were observed during application of baclofen. When paired electrical stimulation (50 ms interval) was applied, the amplitude ratio of the first and second postsynaptic currents was enhanced by baclofen. These results suggest existence of presynaptic GABA_B receptors. These characteristics of the synaptic inputs may be involved in determining the firing properties of the SS neurons.
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