Transportable and non-transportable inhibitors of L-glutamate uptake produce astrocytic stellation and increase EAAT2 cell surface expression.
Astrocytic excitatory amino acid transporters (EAATs) regulate excitatory transmission and limit excitotoxicity. Evidence for a functional interface between EAATs and glial fibrillary acidic protein (GFAP) relevant to astrocytic morphology led to investigations of actions of transportable (D-Aspartate (D-Asp) and (2S,3S,4R)-2-(carboxycyclopropyl)glycine (L-CCG-III)) and non-transportable (DL-threo-beta-benzyloxyaspartate (DL-TBOA)) inhibitors of Glu uptake in murine astrocytes. D-Asp (1 mM), L-CCG-III (0.5 mM) and DL-TBOA (0.5 mM) produced time-dependent (24-72 h) reductions in (3)[H]D-Asp uptake (approximately 30-70%) with little or no gliotoxicity. All drugs induced a profound change in phenotype from cobblestone to stellate morphology and image analysis revealed increases in the intensity of GFAP immunolabelling for L-CCG-III and DL-TBOA. Cytochemistry indicated localized changes in F-actin distribution. Cell surface expression of EAAT2, but not EAAT1, was elevated at 72 h. Blockade of Glu uptake by both types of EAAT inhibitor exerts longer-term effects on astrocytic morphology and a compensatory homeostatic rise in EAAT2 abundance.
Molecular Neuropharmacology, Florey Neuroscience Institutes, Parkville, VIC, 3053, Australia.
Chew L
CL
Lau
Philip M
PM
Beart
Ross D
RD
O'Shea
D000600:Amino Acids, Dicarboxylic / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism / Q000494:pharmacology; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects*; D002478:Cells, Cultured; D018691:Excitatory Amino Acid Antagonists; D027341:Excitatory Amino Acid Transporter 1 / Q000096:biosynthesis; D027342:Excitatory Amino Acid Transporter 2 / Q000096:biosynthesis / Q000235:genetics*; D005971:Glutamates / Q000378:metabolism*; D051379:Mice
D000600:Amino Acids, Dicarboxylic; D018691:Excitatory Amino Acid Antagonists; D027341:Excitatory Amino Acid Transporter 1; D027342:Excitatory Amino Acid Transporter 2; D005971:Glutamates; C493396:Slc1a2 protein, mouse; C493393:Slc1a3 protein, mouse; C120673:benzyloxyaspartate; C035261:(alpha-carboxycyclopropyl)glycine; D001224:Aspartic Acid