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Molecular and Morphological Configuration for 2-Arachidonoylglycerol-Mediated Retrograde Signaling at Mossy Cell-Granule Cell Synapses in the Dentate Gyrus

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Title: Molecular and Morphological Configuration for 2-Arachidonoylglycerol-Mediated Retrograde Signaling at Mossy Cell-Granule Cell Synapses in the Dentate Gyrus
Authors: Uchigashima, Motokazu Browse this author
Yamazaki, Maya Browse this author
Yamasaki, Miwako Browse this author
Tanimura, Asami Browse this author
Sakimura, Kenji Browse this author
Kano, Masanobu Browse this author
Watanabe, Masahiko Browse this author →KAKEN DB
Issue Date: 25-May-2011
Publisher: Society for Neuroscience
Journal Title: The Journal of Neuroscience
Volume: 31
Issue: 21
Start Page: 7700
End Page: 7714
Publisher DOI: 10.1523/JNEUROSCI.5665-10.2011
PMID: 21613483
Abstract: 2-Arachidonoylglycerol (2-AG) is the endocannabinoid that mediates retrograde suppression of neurotransmission in the brain. In the present study, we investigated the 2-AG signaling system at mossy cell (MC)-granule cell (GC) synapses in the mouse dentate gyrus, an excitatory recurrent circuit where endocannabinoids are thought to suppress epileptogenesis. First, we showed by electrophysiology that 2-AG produced by diacylglycerol lipase α(DGLα) mediated both depolarization-induced suppression of excitation and its enhancement by group I metabotropic glutamate receptor activation at MC-GC synapses, as they were abolished in DGLα-knock-out mice. Immunohistochemistry revealed that DGLα was enriched in the neck portion of GC spines forming synapses with MC terminals, whereas cannabinoid CB1 receptors accumulated in the terminal portion of MC axons. On the other hand, the major 2-AG-degrading enzyme, monoacylglycerol lipase (MGL), was absent at MC-GC synapses but was expressed in astrocytes and some inhibitory terminals. Serial electron microscopy clarified that a given GC spine was innervated by a single MC terminal and also contacted nonsynaptically by other MC terminals making synapses with other GC spines in the neighborhood. MGL-expressing elements, however, poorly covered GC spines, amounting to 17% of the total surface of GC spines by astrocytes and 4% by inhibitory terminals. Our findings provide a basis for 2-AG-mediated retrograde suppression of MC-GC synaptic transmission and also suggest that 2-AG released from activated GC spines is readily accessible to nearby MC-GC synapses by escaping from enzymatic degradation. This molecular-anatomical configuration will contribute to adjust network activity in the dentate gyrus after enhanced excitation.
Type: article
URI: http://hdl.handle.net/2115/47503
Appears in Collections:医学院・医学研究院 (Graduate School of Medicine / Faculty of Medicine) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 渡邉 雅彦

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