Abstract

Glutamate can activate NMDA receptor (NMDAR) and subsequently induces excitotoxic neuron loss. However, roles of NMDARs in the blood-brain barrier (BBB) are little known. This study used a mouse cerebrovascular endothelial cell (MCEC) model to evaluate the effects of NMDAR activation on maintenance of the BBB and its possible mechanisms. Analysis of confocal microscopy revealed expressions of NMDAR subunits, GluN1 and GLUN2B, in MCECs. An immunoblot assay further showed the existence of GluN1 in plasma membranes of MCECs. In brain tissues, a confocal microscopic analysis demonstrated co-localization of GluN1 and factor VIII, a biomarker of MCECs. In addition, GluN1 mRNA was detected in MCECs and the brain. Functional assays showed that exposure of MCECs to NMDA increased calcium influx. Separately, NMDA suppressed transendothelial electrical resistance values, levels of occludin, and occludin tight junctions. As to the mechanism, NMDA stimulated sequential phosphorylations of extracellular signal-regulated kinase (ERK)1/2 and mitogen-activated ERK (MEK)1. Interestingly, amounts of matrix metalloproteinase (MMP)2 and MMP9 in MCECs were augmented by NMDA. The NMDA-induced alterations in ERK1/2 phosphorylation and occludin levels were reversed by pretreatment with PD98059, a MEK inhibitor, and MK-801, a NMDAR antagonist, respectively. Therefore, this study shows the functional presence of NMDARs in MCECs, and NMDAR activation can disrupt the MCEC-constructed tight junction barrier via activation of the MEK1/2-ERK1/2 signaling pathway and upregulation of MMP2/9 expressions.

Original languageEnglish
Pages (from-to)40-50
Number of pages11
JournalToxicology
Volume339
DOIs
Publication statusPublished - Jan 2 2016

Fingerprint

Tight Junctions
Endothelial cells
N-Methylaspartate
N-Methyl-D-Aspartate Receptors
Occludin
Endothelial Cells
Maintenance
Phosphorylation
Mitogen-Activated Protein Kinase 3
Chemical activation
Blood-Brain Barrier
Mitogens
Assays
Brain
Acoustic impedance
Dizocilpine Maleate
MAP Kinase Signaling System
Confocal microscopy
Mitogen-Activated Protein Kinase 1
Matrix Metalloproteinase 2

Keywords

  • BBB
  • Cerebrovascular endothelial cells
  • MAPKs
  • MMPs
  • NMDA receptor
  • Occludin tight junction

ASJC Scopus subject areas

  • Toxicology

Cite this

Roles of NMDARs in maintenance of the mouse cerebrovascular endothelial cell-constructed tight junction barrier. / Chen, Jui Tai; Chen, Tyng Guey; Chang, Yung Chia; Chen, Cheng Yu; Chen, Ruei Ming.

In: Toxicology, Vol. 339, 02.01.2016, p. 40-50.

Research output: Contribution to journalArticle

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AU - Chen, Ruei Ming

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