title: CORM-A1 prevents blood-brain barrier dysfunction caused by ionotropic glutamate receptor-mediated endothelial oxidative stress and apoptosis.
abstract: In cerebral microvascular endothelial cells (CMVEC) of newborn pigs, glutamate at excitotoxic concentrations (mM) causes apoptosis mediated by reactive oxygen species (ROS). Carbon monoxide (CO) produced by CMVEC or delivered by a CO-releasing molecule, CORM-A1, has antioxidant properties. We tested the hypothesis that CORM-A1 prevents cerebrovascular endothelial barrier dysfunction caused by glutamate excitotoxicity. First, we identified the glutamate receptors (GluRs) and enzymatic sources of ROS involved in the mechanism of endothelial apoptosis. In glutamate-exposed CMVEC, ROS formation and apoptosis were blocked by rotenone, 2-thenoyltrifluoroacetone (TTFA), and antimycin, indicating that mitochondrial complexes I, II, and III are the major sources of oxidative stress. Agonists of ionotropic GluRs (iGluRs) N-methyl-D-aspartate (NMDA), cis-ACPD, AMPA, and kainate increased ROS production and apoptosis, whereas iGluR antagonists exhibited antiapoptotic properties, suggesting that iGluRs mediate glutamate-induced endothelial apoptosis. The functional consequences of endothelial injury were tested in the model of blood-brain barrier (BBB) composed of CMVEC monolayer on semipermeable membranes. Glutamate and iGluR agonists reduced transendothelial electrical resistance and increased endothelial paracellular permeability to 3-kDa dextran. CORM-A1 exhibited potent antioxidant and antiapoptotic properties in CMVEC and completely prevented BBB dysfunction caused by glutamate and iGluR agonists. Overall, the endothelial component of the BBB is a cellular target for excitotoxic glutamate that, via a mechanism involving a iGluR-mediated activation of mitochondrial ROS production and apoptosis, leads to BBB opening that may be prevented by the antioxidant and antiapoptotic actions of CORMs. Antioxidant CORMs therapy may help preserve BBB functional integrity in neonatal cerebrovascular disease.
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
authors.forename: Shyamali
authors.initials: S
authors.lastname: Basuroy
authors.forename: Charles W
authors.initials: CW
authors.lastname: Leffler
authors.forename: Helena
authors.initials: H
authors.lastname: Parfenova
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001812:Blood-Brain Barrier / Q000378:metabolism* / Q000473:pathology; D001880:Boranes / Q000378:metabolism*; D001921:Brain / Q000378:metabolism / Q000473:pathology; D002254:Carbonates / Q000378:metabolism*; D053938:DNA Fragmentation; D042783:Endothelial Cells / Q000378:metabolism* / Q000473:pathology; D018846:Excitatory Amino Acids / Q000378:metabolism / Q000633:toxicity; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism / Q000633:toxicity; D008297:Male; D018384:Oxidative Stress / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D058468:Receptors, Ionotropic Glutamate / Q000378:metabolism*; D013552:Swine
chemical_list: D001880:Boranes; D002254:Carbonates; D018846:Excitatory Amino Acids; D017382:Reactive Oxygen Species; D058468:Receptors, Ionotropic Glutamate; C503854:sodium boranocarbonate; D018698:Glutamic Acid
keywords: AMPA; NMDA; carbon monoxide; cerebral vascular endothelium; glutamate excitotoxicity; kainate; mitochondria; vascular injury