title: Effects of metabotropic glutamate mGlu5 receptor antagonist on tyrosine phosphorylation of NMDA receptor subunits and cell death in the hippocampus after brain ischemia in rats.
abstract: Tyrosine phosphorylation of the N-methyl-D-aspartate (NMDA) receptor appears to be associated with the regulation of the receptor's ion channel. This study focused on the effect of a metabotropic glutamate mGlu5 receptor antagonist on tyrosine phosphorylation of NMDA receptor subunits and cell death in the hippocampal CA1 region after transient global ischemia and sought to explore their mechanisms. Pretreatment with the mGlu5 receptor antagonist reduced cell death in the hippocampal CA1 region on day 3 after the transient ischemia. Transient ischemia increased the tyrosine phosphorylation of NMDA receptor subunits, which are a major target of Src family tyrosine kinases. Therefore, we investigated the effect of the antagonist on tyrosine phosphorylation of the NMDA receptor subunits after transient ischemia. Tyrosine phosphorylation of the NR2A subunit, but not that of the NR2B one, was inhibited by the mGlu5 receptor antagonist. The administration of the antagonist also attenuated the increase in the amount of active form of Src after the reperfusion. We further demonstrated that the administration of a Src-family kinase inhibitor prevented cell death in the hippocampal CA1 region and attenuated the increase in the tyrosine phosphorylation of the NMDA receptor subunits after the reperfusion. These findings suggest that mGlu5 receptor in the hippocampal CA1 region after transient ischemia is involved in the activation of Src and subsequent tyrosine phosphorylation of NMDA receptor subunits, which actions may contribute to alterations of properties of the NMDA receptor and may be related to pathogenic events leading to neuronal cell death.
authors.affiliation: Department of Molecular and Cellular Pharmacology, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan. takagino@toyaku.ac.jp
authors.forename: Norio
authors.initials: N
authors.lastname: Takagi
authors.forename: Shintaro
authors.initials: S
authors.lastname: Besshoh
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Marunouchi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Takeo
authors.forename: Kouichi
authors.initials: K
authors.lastname: Tanonaka
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D056547:CA1 Region, Hippocampal / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D008297:Male; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D018691:Excitatory Amino Acid Antagonists; D011725:Pyridines; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D014443:Tyrosine; D019061:src-Family Kinases; C121001:NR2B NMDA receptor; C121465:6-methyl-2-(phenylethynyl)pyridine