Structural alterations of tight junctions are associated with loss of polarity in stroke-prone spontaneously hypertensive rat blood-brain barrier endothelial cells

Item Type:	Article
Title:	Structural alterations of tight junctions are associated with loss of polarity in stroke-prone spontaneously hypertensive rat blood-brain barrier endothelial cells
Creators Name:	Lippoldt, A. and Kniesel, U. and Liebner, S. and Kalbacher, H. and Kirsch, T. and Wolburg, H. and Haller, H.
Abstract:	The mechanisms leading to stroke in stroke-prone spontaneously hypertensive rats (SHRSP) are not well understood. We tested the hypothesis that the endothelial tight junctions of the blood-brain barrier are altered in SHRSP prior to stroke. We investigated tight junctions in 13-week-old SHRSP, spontaneously hypertensive stroke-resistant rats (SHR) and age-matched Wistar-Kyoto rats (WKY) by electron microscopy and immunocytochemistry. Ultrathin sections showed no difference in junction structure of cerebral capillaries from SHRSP, SHR and WKY, respectively. However, using freeze-fracturing, we observed that the blood-brain barrier specific distribution of tight junction particles between P- and E-face in WKY (58.7±3.6%, P-face; 41.2±5.59%, E-face) and SHR (53.2±19.3%, P-face; 55.6±13.25%, E-face) was changed to an 89.4±9.9% predominant E-face association in cerebral capillaries from SHRSP. However, the expression of the tight junction molecules ZO-1, occludin, claudin-1 and claudin-5 was not changed in capillaries of SHRSP. Permeability of brain capillaries from SHRSP was not different compared to SHR and WKY using lanthanum nitrate as a tracer. In contrast, analysis of endothelial cell polarity by distribution of the glucose-1 transporter (Glut-1) revealed that its abluminal:luminal ratio was reduced from 4:1 in SHR and WKY to 1:1 in endothelial cells of cerebral capillaries of SHRSP. In summary, we demonstrate that early changes exist in cerebral capillaries from a genetic model of hypertension-associated stroke. We suggest that a disturbed fence function of the tight junctions in SHRSP blood-brain barrier endothelial cells may lead to subtle changes in polarity. These changes may contribute to the pathogenesis of stroke.
Keywords:	Blood-Brain Barrier, Hypertension, Stroke
Source:	Brain Research
ISSN:	0006-8993
Publisher:	Elsevier
Volume:	885
Number:	2
Page Range:	251-261
Date:	1 January 2000
PubMed:	View item in PubMed

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