Astrocyte aquaporin mediates a tonic water efflux maintaining brain homeostasis

Autor: Cuong Pham, Yuji Komaki, Anna Deàs-Just, Benjamin Le Gac, Christine Mouffle, Clara Franco, Agnès Chaperon, Vincent Vialou, Tomokazu Tsurugizawa, Bruno Cauli, Dongdong Li
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: eLife, Vol 13 (2024)
Druh dokumentu: article
ISSN: 2050-084X
DOI: 10.7554/eLife.95873
Popis: Brain water homeostasis not only provides a physical protection, but also determines the diffusion of chemical molecules key for information processing and metabolic stability. As a major type of glia in brain parenchyma, astrocytes are the dominant cell type expressing aquaporin water channel. How astrocyte aquaporin contributes to brain water homeostasis in basal physiology remains to be understood. We report that astrocyte aquaporin 4 (AQP4) mediates a tonic water efflux in basal conditions. Acute inhibition of astrocyte AQP4 leads to intracellular water accumulation as optically resolved by fluorescence-translated imaging in acute brain slices, and in vivo by fiber photometry in mobile mice. We then show that aquaporin-mediated constant water efflux maintains astrocyte volume and osmotic equilibrium, astrocyte and neuron Ca2+ signaling, and extracellular space remodeling during optogenetically induced cortical spreading depression. Using diffusion-weighted magnetic resonance imaging (DW-MRI), we observed that in vivo inhibition of AQP4 water efflux heterogeneously disturbs brain water homeostasis in a region-dependent manner. Our data suggest that astrocyte aquaporin, though bidirectional in nature, mediates a tonic water outflow to sustain cellular and environmental equilibrium in brain parenchyma.
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