Cellular mechanisms of protection by metabotropic glutamate receptors during anoxia and nitric oxide toxicity.
Metabotropic glutamate receptors, nitric oxide (NO), and the signal transduction pathways of protein kinase C (PKC) and protein kinase A (PKA) can independently alter ischemic-induced neuronal cell death. We therefore examined whether the protective effects of metabotropic glutamate receptors during anoxia and NO toxicity were mediated through the cellular pathways of PKC or PKA in primary hippocampal neurons. Pretreatment with the metabotropic glutamate receptor agonists (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid, (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD), and L(+)-2-amino-4-phosphonobutyric acid (L-AP4) 1 h before anoxia or NO exposure increased hippocampal neuronal cell survival from approximately 30 to 70%. In addition, posttreatment with 1S,3R-ACPD or L-AP4 up to 6 h following an insult attenuated anoxic- or NO-induced neurodegeneration. In contrast, treatment with L-(+)-2-amino-3-phosphonopropionic acid, an antagonist of the metabotropic glutamate receptor, did not significantly alter neuronal survival during anoxia or NO exposure. Protection by the ACPD-sensitive metabotropic receptors, such as the subtypes mGluR1 alpha, mGluR2, and mGluR5, appears to be dependent on the modulation of PKC activity. In contrast, L-AP4-sensitive metabotropic glutamate receptors, such as the subtype mGluR4, may increase neuronal survival through PKA rather than PKC. Thus, activation of specific metabotropic glutamate receptors is protective during anoxia and NO toxicity, but the signal transduction pathways mediating protection differ among the metabotropic glutamate receptor subtypes.
Maiese
K
K
Department of Neurology, Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
Swiriduk
M
M
TenBroeke
M
M
D000409:Alanine / Q000031:analogs & derivatives / Q000494:pharmacology; D000613:Aminobutyrates / Q000494:pharmacology; D000818:Animals; D002545:Brain Ischemia / Q000517:prevention & control; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology; D009474:Neurons / Q000166:cytology* / Q000201:enzymology; D018696:Neuroprotective Agents / Q000494:pharmacology; D009498:Neurotoxins / Q000494:pharmacology; D009569:Nitric Oxide / Q000633:toxicity*; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D000613:Aminobutyrates; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D018696:Neuroprotective Agents; D009498:Neurotoxins; D018094:Receptors, Metabotropic Glutamate; C000211:2-amino-3-phosphonopropionic acid; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; D009569:Nitric Oxide; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; C012729:2-amino-4-phosphonobutyric acid; D000409:Alanine