CORM-A1 prevents blood-brain barrier dysfunction caused by ionotropic glutamate receptor-mediated endothelial oxidative stress and apoptosis

Am J Physiol Cell Physiol. 2013 Jun 1;304(11):C1105-15. doi: 10.1152/ajpcell.00023.2013. Epub 2013 Apr 10.

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.

Keywords: AMPA; NMDA; carbon monoxide; cerebral vascular endothelium; glutamate excitotoxicity; kainate; mitochondria; vascular injury.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Apoptosis / physiology*
  • Blood-Brain Barrier / metabolism*
  • Blood-Brain Barrier / pathology
  • Boranes / metabolism*
  • Brain / metabolism
  • Brain / pathology
  • Carbonates / metabolism*
  • DNA Fragmentation
  • Endothelial Cells / metabolism*
  • Endothelial Cells / pathology
  • Excitatory Amino Acids / metabolism
  • Excitatory Amino Acids / toxicity
  • Female
  • Glutamic Acid / metabolism
  • Glutamic Acid / toxicity
  • Male
  • Oxidative Stress / physiology*
  • Reactive Oxygen Species / metabolism
  • Receptors, Ionotropic Glutamate / metabolism*
  • Swine

Substances

  • Boranes
  • Carbonates
  • Excitatory Amino Acids
  • Reactive Oxygen Species
  • Receptors, Ionotropic Glutamate
  • sodium boranocarbonate
  • Glutamic Acid