Glutamate mediates platelet activation through the AMPA receptor.
Glutamate is an excitatory neurotransmitter that binds to the kainate receptor, the N-methyl-D-aspartate (NMDA) receptor, and the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor (AMPAR). Each receptor was first characterized and cloned in the central nervous system (CNS). Glutamate is also present in the periphery, and glutamate receptors have been identified in nonneuronal tissues, including bone, heart, kidney, pancreas, and platelets. Platelets play a central role in normal thrombosis and hemostasis, as well as contributing greatly to diseases such as stroke and myocardial infarction. Despite the presence of glutamate in platelet granules, the role of glutamate during hemostasis is unknown. We now show that activated platelets release glutamate, that platelets express AMPAR subunits, and that glutamate increases agonist-induced platelet activation. Furthermore, we demonstrate that glutamate binding to the AMPAR increases intracellular sodium concentration and depolarizes platelets, which are important steps in platelet activation. In contrast, platelets treated with the AMPAR antagonist CNQX or platelets derived from GluR1 knockout mice are resistant to AMPA effects. Importantly, mice lacking GluR1 have a prolonged time to thrombosis in vivo. Our data identify glutamate as a regulator of platelet activation, and suggest that the AMPA receptor is a novel antithrombotic target.
Morrell
Craig N
CN
Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. cmorrell@jhmi.edu
Sun
Henry
H
Ikeda
Masahiro
M
Beique
Jean-Claude
JC
Swaim
Anne Marie
AM
Mason
Emily
E
Martin
Tanika V
TV
Thompson
Laura E
LE
Gozen
Oguz
O
Ampagoomian
David
D
Sprengel
Rolf
R
Rothstein
Jeffrey
J
Faraday
Nauder
N
Huganir
Richard
R
Lowenstein
Charles J
CJ
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D018698:Glutamic Acid / Q000097:blood* / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D017136:Ion Transport; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials; D051379:Mice; D018345:Mice, Knockout; D015539:Platelet Activation / Q000187:drug effects / Q000502:physiology*; D018091:Receptors, AMPA / Q000819:agonists / Q000037:antagonists & inhibitors / Q000097:blood* / Q000172:deficiency / Q000235:genetics; D043562:Receptors, G-Protein-Coupled / Q000819:agonists / Q000097:blood; D016194:Receptors, N-Methyl-D-Aspartate / Q000097:blood; D015398:Signal Transduction; D012964:Sodium / Q000097:blood; D013927:Thrombosis / Q000097:blood; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000097:blood / Q000494:pharmacology
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D018698:Glutamic Acid; D007608:Kainic Acid; D018091:Receptors, AMPA; D043562:Receptors, G-Protein-Coupled; D016194:Receptors, N-Methyl-D-Aspartate; D012964:Sodium; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid