Endothelin-1 decreases glutamate uptake in primary cultured rat astrocytes.
Endothelin-1 (ET-1) is a potent vasoconstrictor peptide that is also known to induce a wide spectrum of biological responses in nonvascular tissue. In this study, we found that ET-1 (100 nM) inhibited the glutamate uptake in cultured astrocytes expressing the glutamate/aspartate transporter (GLAST); astrocytes did not express the glutamate transporter-1 (GLT-1). The V(max) and the K(m) of the glutamate uptake were reduced by 57% and 47%, respectively. Application of the ET(A) and ET(B) receptor antagonists BQ-123 and BQ-788 partly inhibited the ET-1-evoked decrease in the glutamate uptake, whereas the nonspecific ET receptor antagonist bosentan completely inhibited this decrease. Incubation of the cultures with pertussis toxin abolished the effect of ET-1 on the uptake. The ET-1-induced decrease in the glutamate uptake was independent of extracellular free Ca(2+) concentration, whereas the intracellular Ca(2+) antagonists thapsigargin and 3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester abolished the effect of ET-1 on the glutamate uptake. Incubation with the protein kinase C (PKC) antagonist staurosporine, but not with the fatty acid-binding protein bovine serum albumin, prevented the ET-1-induced decrease in the glutamate uptake. These results suggest that ET-1 impairs the high-affinity glutamate uptake in cultured astrocytes through a G protein-coupled mechanism, involving PKC and changes in intracellular Ca(2+).
Leonova
J
J
Institute of Clinical Neuroscience, Göteborg University, Göteborg, Sweden.
Thorlin
T
T
Aberg
N D
ND
Eriksson
P S
PS
Rönnbäck
L
L
Hansson
E
E
D000595:Amino Acid Sequence; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D017609:Barium Compounds / Q000494:pharmacology; D015153:Blotting, Western; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002712:Chlorides / Q000494:pharmacology; D003864:Depression, Chemical; D019332:Endothelin-1 / Q000494:pharmacology*; D018698:Glutamic Acid / Q000378:metabolism*; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D051381:Rats; D017207:Rats, Sprague-Dawley; D014161:Transduction, Genetic
D017609:Barium Compounds; D002712:Chlorides; D019332:Endothelin-1; C024986:barium chloride; D018698:Glutamic Acid