2002 Fiscal Year Final Research Report Summary
Physiological roles of plasticity of inhibitory synaptic transmission
| Project/Area Number |
13680899
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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 |
神経・脳内生理学
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| Research Institution | Kanazawa University |
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Principal Investigator |
OHNO-SHOSAKU Takako Kanazawa University, Department of Cellular Neurophysiology assistant professor, 大学院・医学系研究科, 助教授 (60179025)
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| Project Period (FY) |
2001 – 2002
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| Keywords | retrograde signal / endocannabinoid / cannabinoid receptor / synaptic modulation / hippocampus / inhibitory synaptic transmission / muscarinic receptor / metabotropic glutamate receptor |
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| Research Abstract |
1. Recent studies have revealed that the activity of postsynaptic neurons can influence presynaptic functions via endocannabinoids that are released from postsynaptic neurons and act retrogradely on presynaptic terminals. In this study, we attempted to clarify physiological roles of endocannabinoid-mediated retrograde modulation of synaptic transmissions.
2. We made paired whole-cell recordings from cultured hippocampal neurons prepared from newborn rats, and recorded evoked excitatory and inhibitory postsynaptic currents. Our results are summarized as follows. (1) Endocannabinoids can be released from postsynaptic neurons by depolarization or by activation of group I metabotropic glutamate receptors (mGluR) (Ohno-Shosaku et al., Eur J Neurosci 15, 2002). (2) Endocannabinoid release is also induced by activation of the M_1 and M_3 subtypes of muscarinic acetylcholine receptors (in preparation), (3) Postsynaptic depolarization and activation of group I mGluRs or M_1/M_3 receptors work in a cooperative manner to release endocannabinoids (Ohno-Shosaku et al., Eur J Neurosci, in press). (4) The released endocannabinoids act retrogradely onto presynaptic cannabinoid CB1 receptors and suppress the transmitter release from presynaptic terminals. (5) The cannabinoid-sensitivity of presynaptic terminals is high in a subpopulation (about 50 %) of inhibitory synapses, low in excitatory synapses, and almost absent in the rest of inhibitory synapses (Ohno-Shosaku et al., J Neurosci 22, 2002).
3. These results suggest that endocannabinoids mediate target-specific retrograde signals, by which the postsynaptic neuronal activity influences the transmitter release from certain types of presynaptic terminals.
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