Epileptiform activity induces vascular remodeling and zonula occludens 1 downregulation in organotypic hippocampal cultures: role of VEGF signaling pathways

• Published in: The Journal of neuroscience 2011-07, Vol.31 (29), p.10677-10688
• Main Authors: Morin-Brureau, Mélanie, Lebrun, Aurore, Rousset, Marie-Claude, Fagni, Laurent, Bockaert, Joël, de Bock, Frédéric, Lerner-Natoli, Mireille
• Format: Article
• Language: English
• Subjects: Anesthetics, Local - pharmacology; Animals; Animals, Newborn; Antibodies - pharmacology; Brain Waves - drug effects; Brain Waves - physiology; Down-Regulation - drug effects; Down-Regulation - physiology; Drug Interactions; Endothelium, Vascular - drug effects; Endothelium, Vascular - physiology; Hippocampus - drug effects; Hippocampus - physiology; Immunology; Innate immunity; Kainic Acid - pharmacology; L-Lactate Dehydrogenase - metabolism; Life Sciences; Membrane Proteins - metabolism; Nerve Tissue Proteins - metabolism; Neurons and Cognition; Organ Culture Techniques; Phosphoproteins - metabolism; Propidium; Rats; Rats, Sprague-Dawley; Signal Transduction - drug effects; Signal Transduction - physiology; Teprotide - pharmacology; Tetrodotoxin - pharmacology; Time Factors; Vascular Endothelial Growth Factor A - immunology; Vascular Endothelial Growth Factor A - metabolism; Vascular Endothelial Growth Factor Receptor-2 - metabolism; Zonula Occludens-1 Protein
• ISSN: 0270-6474; 1529-2401
• DOI: 10.1523/JNEUROSCI.5692-10.2011

Recent studies suggest that blood-brain barrier (BBB) permeability contributes to epileptogenesis in symptomatic epilepsies. We have previously described angiogenesis, aberrant vascularization, and BBB alteration in drug-refractory temporal lobe epilepsy. Here, we investigated the role of vascular endothelial growth factor (VEGF) in an in vitro integrative model of vascular remodeling induced by epileptiform activity in rat organotypic hippocampal cultures. After kainate-induced seizure-like events (SLEs), we observed an overexpression of VEGF and VEGF receptor-2 (VEGFR-2) as well as receptor activation. Vascular density and branching were significantly increased, whereas zonula occludens 1 (ZO-1), a key protein of tight junctions (TJs), was downregulated. These effects were fully prevented by VEGF neutralization. Using selective inhibitors of VEGFR-2 signaling pathways, we found that phosphatidylinositol 3-kinase is involved in cell survival, protein kinase C (PKC) in vascularization, and Src in ZO-1 regulation. Recombinant VEGF reproduced the kainate-induced vascular changes. As in the kainate model, VEGFR-2 and Src were involved in ZO-1 downregulation. These results showed that VEGF/VEGFR-2 initiates the vascular remodeling induced by SLEs and pointed out the roles of PKC in vascularization and Src in TJ dysfunction, respectively. This suggests that Src pathway could be a therapeutic target for BBB protection in epilepsies.