Abstract
Adult neurogenesis occurs in the hippocampus and the olfactory bulb of the mammalian CNS. Recent studies have demonstrated that newborn granule cells of the adult hippocampus are postsynaptic targets of excitatory and inhibitory neurons, but evidence of synapse formation by the axons of these cells is still lacking. By combining retroviral expression of green fluorescent protein in adult-born neurons of the mouse dentate gyrus with immuno-electron microscopy, we found output synapses that were formed by labeled terminals on appropriate target cells in the CA3 area and the hilus. Furthermore, retroviral expression of channelrhodopsin-2 allowed us to light-stimulate newborn granule cells and identify postsynaptic target neurons by whole-cell recordings in acute slices. Our structural and functional evidence indicates that axons of adult-born granule cells establish synapses with hilar interneurons, mossy cells and CA3 pyramidal cells and release glutamate as their main neurotransmitter.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Action Potentials / drug effects
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Action Potentials / physiology
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Action Potentials / radiation effects
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Animals
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Carrier Proteins / biosynthesis
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Carrier Proteins / genetics
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Dentate Gyrus / cytology*
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Dentate Gyrus / metabolism
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Dentate Gyrus / virology
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Female
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GABA Antagonists / pharmacology
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Gene Transfer Techniques
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Genes, Reporter
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Glutamic Acid / metabolism
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Humans
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Interneurons / physiology
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Interneurons / ultrastructure
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Light
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Luminescent Proteins / biosynthesis
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Luminescent Proteins / genetics
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Mice
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Mice, Inbred C57BL
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Moloney murine leukemia virus / genetics
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Mossy Fibers, Hippocampal / metabolism
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Mossy Fibers, Hippocampal / ultrastructure
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Mossy Fibers, Hippocampal / virology
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Neurons / drug effects
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Neurons / physiology*
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Neurons / radiation effects
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Organ Culture Techniques
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Patch-Clamp Techniques
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Photic Stimulation
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Presynaptic Terminals / physiology
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Presynaptic Terminals / ultrastructure
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Synapses / genetics
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Synapses / physiology*
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Synapses / ultrastructure
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Synaptic Transmission / drug effects
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Synaptic Transmission / physiology*
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Synaptic Transmission / radiation effects
Substances
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Carrier Proteins
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GABA Antagonists
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Luminescent Proteins
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channelopsin-2, Chlamydomonas reinhardtii
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Glutamic Acid