RGD Reference Report - SNAT3-mediated glutamine transport in perisynaptic astrocytes in situ is regulated by intracellular sodium. - Rat Genome Database

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SNAT3-mediated glutamine transport in perisynaptic astrocytes in situ is regulated by intracellular sodium.

Authors: Todd, Alison C  Marx, Mari-Carmen  Hulme, Sarah R  Bröer, Stefan  Billups, Brian 
Citation: Todd AC, etal., Glia. 2017 Jun;65(6):900-916. doi: 10.1002/glia.23133. Epub 2017 Mar 8.
RGD ID: 152995559
Pubmed: PMID:28272791   (View Abstract at PubMed)
DOI: DOI:10.1002/glia.23133   (Journal Full-text)

The release of glutamine from astrocytes adjacent to synapses in the central nervous system is thought to play a vital role in the mechanism of glutamate recycling and is therefore important for maintaining excitatory neurotransmission. Here we investigate the nature of astrocytic membrane transport of glutamine in rat brainstem slices, using electrophysiological recording and fluorescent imaging of pHi and Nai+. Glutamine application to perisynaptic astrocytes induced a membrane current, caused by activation of system A (SA) family transporters. A significant electroneutral component was also observed, which was mediated by the system N (SN) family transporters. This response was stimulated by glutamine (KM of 1.57 mM), histidine, and asparagine, but not by leucine or serine, indicating activation of the SNAT3 isoform of SN. We hypothesized that increasing the [Na+ ]i would alter the SNAT3 transporter equilibrium, thereby stimulating glutamine release. In support of this hypothesis, we show that SNAT3 transport can be driven by changing cation concentration and that manipulations to raise [Na+ ]i (activation of excitatory amino acid transporters (EAATs), SA transporters or AMPA receptors) all directly influence SNAT3 transport rate. A kinetic model of glutamine fluxes is presented, which shows that EAAT activation causes the release of glutamine, driven mainly by the increased [Na+ ]i . These data demonstrate that SNAT3 is functionally active in perisynaptic astrocytes in situ. As a result, astrocytic Nai+ signaling, as would be stimulated by neighboring synaptic activity, has the capacity to stimulate astrocytic glutamine release to support glutamate recycling.

Gene Ontology Annotations    

Biological Process

Objects Annotated

Genes (Rattus norvegicus)
Slc38a3  (solute carrier family 38, member 3)

Additional Information