Abstract
Blockade of ionotropic glutamate receptors induces neuronal cell apoptosis. We investigated if mitochondria-mediated death signals would contribute to neuronal apoptosis following administration of glutamate antagonists. The administration of MK-801 and CNQX (MK-801/CNQX), the selective antagonists of N-methyl-d-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptors, produced widespread neuronal death in neonatal rat brain and cortical cell cultures. MK-801/CNQX-induced neuronal apoptosis was prevented by zVAD-fmk, a broad inhibitor of caspases, but insensitive to inhibitors of calpain or cathepsin D. Activation of caspase-3 was observed within 6-12 h and sustained over 36 h after exposure to MK-801/CNQX, which cleaved PHF-1 tau, the substrate for caspase-3. Activation of caspase-3 was blocked by high K+ and mimicked by BAPTA-AM, a selective Ca2+ chelator. Reducing extracellular Ca2+, but not Na+, activated caspase-3, suggesting an essential role of Ca2+ deficiency in MK-801/CNQX-induced activation of caspases. Cortical neurons treated with MK-801/CNQX triggered activation of caspase-9, release of cytochrome c from mitochondria, and translocation of Bax into mitochondria. The present study suggests that blockade of ionotropic glutamate receptors causes caspase-3-mediated neuronal apoptosis due to Ca2+ deficiency that is coupled to the sequential mitochondrial death pathway.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
6-Cyano-7-nitroquinoxaline-2,3-dione / pharmacology
-
Animals
-
Apoptosis / drug effects
-
Apoptosis / physiology*
-
Calcium / deficiency*
-
Calcium / metabolism
-
Caspase 3
-
Caspase 9
-
Caspase Inhibitors
-
Caspases / metabolism
-
Cells, Cultured
-
Cerebral Cortex / cytology
-
Chelating Agents / pharmacology
-
Cytochrome c Group / metabolism
-
Dizocilpine Maleate / pharmacology
-
Enzyme Inhibitors / pharmacology
-
Excitatory Amino Acid Antagonists / pharmacology
-
Mice
-
Neurons / cytology
-
Neurons / drug effects*
-
Neurons / metabolism*
-
Potassium / pharmacology
-
Protein Transport / drug effects
-
Proto-Oncogene Proteins / metabolism
-
Proto-Oncogene Proteins c-bcl-2*
-
Rats
-
Rats, Sprague-Dawley
-
Receptors, AMPA / antagonists & inhibitors
-
Receptors, AMPA / metabolism
-
Receptors, Glutamate / drug effects*
-
Receptors, Glutamate / metabolism
-
Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors
-
Receptors, N-Methyl-D-Aspartate / metabolism
-
bcl-2-Associated X Protein
Substances
-
Bax protein, mouse
-
Bax protein, rat
-
Caspase Inhibitors
-
Chelating Agents
-
Cytochrome c Group
-
Enzyme Inhibitors
-
Excitatory Amino Acid Antagonists
-
Proto-Oncogene Proteins
-
Proto-Oncogene Proteins c-bcl-2
-
Receptors, AMPA
-
Receptors, Glutamate
-
Receptors, N-Methyl-D-Aspartate
-
bcl-2-Associated X Protein
-
Dizocilpine Maleate
-
6-Cyano-7-nitroquinoxaline-2,3-dione
-
Casp3 protein, mouse
-
Casp3 protein, rat
-
Casp9 protein, mouse
-
Casp9 protein, rat
-
Caspase 3
-
Caspase 9
-
Caspases
-
Potassium
-
Calcium