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Aquaporin‐4 regulates extracellular space volume dynamics during high‐frequency synaptic stimulation: A gene deletion study in mouse hippocampus
Author(s) -
HajYasein Nadia Nabil,
Jensen Vidar,
Østby Ivar,
Omholt Stig W.,
Voipio Juha,
Kaila Kai,
Ottersen Ole P.,
Hvalby Øivind,
Nagelhus Erlend A.
Publication year - 2012
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/glia.22319
Subject(s) - biology , neuroscience , extracellular , hippocampus , excitatory postsynaptic potential , hippocampal formation , aquaporin , pyramidal cell , schaffer collateral , central nervous system , microbiology and biotechnology , aquaporin 4 , stimulation , nervous system , biochemistry , inhibitory postsynaptic potential
Little is known about the physiological roles of aquaporin‐4 (AQP4) in the central nervous system. AQP4 water channels are concentrated in endfeet membranes of astrocytes but also localize to the fine astrocytic processes that abut central synapses. Based on its pattern of expression, we predicted that AQP4 could be involved in controlling water fluxes and changes in extracellular space (ECS) volume that are associated with activation of excitatory pathways. Here, we show that deletion of Aqp4 accentuated the shrinkage of the ECS that occurred in the mouse hippocampal CA1 region during activation of Schaffer collateral/commissural fibers. This effect was found in the stratum radiatum (where perisynaptic astrocytic processes abound) but not in the pyramidal cell layer (where astrocytic processes constitute but a minor volume fraction). For both genotypes the ECS shrinkage was most pronounced in the pyramidal cell layer. Our data attribute a physiological role to AQP4 and indicate that this water channel regulates extracellular volume dynamics in the mammalian brain. © 2012 Wiley Periodicals, Inc.