Endothelial endothelin-1 over-expression using receptor tyrosine kinase tie-1 promoter leads to more severe vascular permeability and blood brain barrier breakdown after transient middle cerebral artery occlusion

Endothelin-1 (ET-1) is up-regulated in the endothelial cells and astrocytes under ischemia. Transgenic mice with astrocytic ET-1 over-expression (GET-1) showed more severe neurological deficit and larger infarct after transient middle cerebral artery occlusion (MCAO). Here, the significance of endothelial ET-1 in ischemic brain injury was investigated using transgenic mice with the endothelial ET-1 over-expression (TET-1). Increased ET-1 level was observed in the TET-1 brain infarct core after transient MCAO. ETA receptor expression was induced in the penumbra and ETA antagonist (A-147627) partially normalized the infarct volume and neurological deficit. In the infarct core of TET-1 brain, superoxide, nitrotyrosine, and gp91(phox) levels were increased. TET-1 brain displayed increased matrix metalloproteinase-2 expression, water content, immunoglobulin leakage and decreased occludin level in the ipsilateral hemisphere indicative of BBB breakdown and hemispheric edema. Interestingly, AQP-4 expression was increased in the penumbra of TET-1 brain following transient MCAO leading to the water accumulation. Taken together, endothelial ET-1 over-expression and ETA receptor activation contributes to the increased oxidative stress, water accumulation and BBB breakdown after transient MCAO leading to more severe neurological deficit and increased infarct. (C) 2009 Elsevier B.V. All rights reserved.