title: Properties of doublecortin expressing neurons in the adult mouse dentate gyrus.
abstract: The dentate gyrus is a neurogenic zone where neurons continue to be born throughout life, mature and integrate into the local circuitry. In adults, this generation of new neurons is thought to contribute to learning and memory formation. As newborn neurons mature, they undergo a developmental sequence in which different stages of development are marked by expression of different proteins. Doublecortin (DCX) is an early marker that is expressed in immature granule cells that are beginning migration and dendritic growth but is turned off before neurons reach maturity. In the present study, we use a mouse strain in which enhanced green fluorescent protein (EGFP) is expressed under the control of the DCX promoter. We show that these neurons have high input resistances and some cells can discharge trains of action potentials. In mature granule cells, action potentials are followed by a slow afterhyperpolarization that is absent in EGFP-positive neurons. EGFP-positive neurons had a lower spine density than mature neurons and stimulation of either the medial or lateral perforant pathway activated dual component glutamatergic synapses that had both AMPA and NMDA receptors. NMDA receptors present at these synapses had slow kinetics and were blocked by ifenprodil, indicative of high GluN2B subunit content. These results show that EGFP-positive neurons in the DCX-EGFP mice are functionally immature both in their firing properties and excitatory synapses.
authors.affiliation: The Queensland Brain Institute, The University of Queensland, Brisbane, Australia.
authors.forename: Jay
authors.initials: J
authors.lastname: Spampanato
authors.forename: Robert K
authors.initials: RK
authors.lastname: Sullivan
authors.forename: Fabrice R
authors.initials: FR
authors.lastname: Turpin
authors.forename: Perry F
authors.initials: PF
authors.lastname: Bartlett
authors.forename: Pankaj
authors.initials: P
authors.lastname: Sah
mesh_terms: D000200:Action Potentials; D000818:Animals; D000831:Animals, Newborn; D064032:Calbindin 2; D002465:Cell Movement; D018891:Dentate Gyrus / Q000378:metabolism*; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D005260:Female; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007700:Kinetics; D008297:Male; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis* / Q000235:genetics*; D039842:Neural Cell Adhesion Molecule L1 / Q000096:biosynthesis; D055495:Neurogenesis; D009474:Neurons / Q000378:metabolism*; D009479:Neuropeptides / Q000096:biosynthesis* / Q000235:genetics*; D010880:Piperidines / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D018091:Receptors, AMPA / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000096:biosynthesis / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000096:biosynthesis; D012794:Sialic Acids / Q000096:biosynthesis; D013569:Synapses / Q000378:metabolism
chemical_list: D064032:Calbindin 2; C000714847:Dcx protein, mouse; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D008869:Microtubule-Associated Proteins; C121001:NR2B NMDA receptor; D039842:Neural Cell Adhesion Molecule L1; D009479:Neuropeptides; D010880:Piperidines; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; D064030:S100 Calcium Binding Protein G; D012794:Sialic Acids; C103469:polysialyl neural cell adhesion molecule; D049452:Green Fluorescent Proteins; C010739:ifenprodil