Astrocytic glutamate uptake is slow and does not limit neuronal NMDA receptor activation in the neonatal neocortex.
Glutamate uptake by astrocytes controls the time course of glutamate in the extracellular space and affects neurotransmission, synaptogenesis, and circuit development. Astrocytic glutamate uptake has been shown to undergo post-natal maturation in the hippocampus, but has been largely unexplored in other brain regions. Notably, glutamate uptake has never been examined in the developing neocortex. In these studies, we investigated the development of astrocytic glutamate transport, intrinsic membrane properties, and control of neuronal NMDA receptor activation in the developing neocortex. Using astrocytic and neuronal electrophysiology, immunofluorescence, and Western blot analysis we show that: (1) glutamate uptake in the neonatal neocortex is slow relative to neonatal hippocampus; (2) astrocytes in the neonatal neocortex undergo a significant maturation of intrinsic membrane properties; (3) slow glutamate uptake is accompanied by lower expression of both GLT-1 and GLAST; (4) glutamate uptake is less dependent on GLT-1 in neonatal neocortex than in neonatal hippocampus; and (5) the slow glutamate uptake we report in the neonatal neocortex corresponds to minimal astrocytic control of neuronal NMDA receptor activation. Taken together, our results clearly show fundamental differences between astrocytic maturation in the developing neocortex and hippocampus, and corresponding changes in how astrocytes control glutamate signaling.
Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts.|Neuroscience Program, Tufts Sackler School of Biomedical Sciences, Boston, Massachusetts.
Elizabeth
E
Hanson
Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts.
Moritz
M
Armbruster
Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts.
David
D
Cantu
Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts.|Neuroscience Program, Tufts Sackler School of Biomedical Sciences, Boston, Massachusetts.
Lauren
L
Andresen
Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts.
Amaro
A
Taylor
Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
Niels Christian
NC
Danbolt
Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts.|Neuroscience Program, Tufts Sackler School of Biomedical Sciences, Boston, Massachusetts.
Chris G
CG
Dulla
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D018683:Excitatory Amino Acid Agents / Q000494:pharmacology; D027341:Excitatory Amino Acid Transporter 1 / Q000378:metabolism; D027342:Excitatory Amino Acid Transporter 2 / Q000378:metabolism; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D018756:GABA Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology; D066298:In Vitro Techniques; D019579:Neocortex / Q000166:cytology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D009924:Organ Culture Techniques; D011724:Pyridazines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*
D018683:Excitatory Amino Acid Agents; D027341:Excitatory Amino Acid Transporter 1; D027342:Excitatory Amino Acid Transporter 2; D018756:GABA Antagonists; D011724:Pyridazines; D016194:Receptors, N-Methyl-D-Aspartate; C493395:Slc1a2 protein, rat; C493392:Slc1a3 protein, rat; D018698:Glutamic Acid; C049853:gabazine
EAAT1; EAAT2; GLAST; GLT-1; developmental plasticity; glial development; membrane resistance; postnatal development