Neurons born in the adult dentate gyrus form functional synapses with target cells.
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.
Toni
Nicolas
N
Laboratory of Genetics, Salk Institute, 10010 North Torrey Pines Road, La Jolla, California 92037, USA.
Laplagne
Diego A
DA
Zhao
Chunmei
C
Lombardi
Gabriela
G
Ribak
Charles E
CE
Gage
Fred H
FH
Schinder
Alejandro F
AF
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics; D018891:Dentate Gyrus / Q000166:cytology* / Q000378:metabolism / Q000821:virology; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D018014:Gene Transfer Techniques; D017930:Genes, Reporter; D018698:Glutamic Acid / Q000378:metabolism; D006801:Humans; D007395:Interneurons / Q000502:physiology / Q000648:ultrastructure; D008027:Light; D008164:Luminescent Proteins / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008979:Moloney murine leukemia virus / Q000235:genetics; D019599:Mossy Fibers, Hippocampal / Q000378:metabolism / Q000648:ultrastructure / Q000821:virology; D009474:Neurons / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D010775:Photic Stimulation; D017729:Presynaptic Terminals / Q000502:physiology / Q000648:ultrastructure; D013569:Synapses / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects
D002352:Carrier Proteins; D018756:GABA Antagonists; D008164:Luminescent Proteins; C523009:channelopsin-2, Chlamydomonas reinhardtii; D018698:Glutamic Acid