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Post-ischemic hypothermia attenuates loss of the vascular basement membrane proteins, agrin and SPARC, and the blood-brain barrier disruption after global cerebral ischemia.

Abstract：

:Vascular basement membrane (BM) stabilizes brain vessels and inhibits endothelial cell cycle. Cerebral ischemia causes BM breakdown with the loss of structural BM components including collagens and laminins. In this study, the expression changes of the BM proteoglycan agrin, and the non-structural BM constituent SPARC (BM-40, osteonectin), were studied in brain vessels after global cerebral ischemia. A transient 20-min forebrain ischemia followed by 1, 6 or 24 h of reperfusion was induced in adult Sprague-Dawley rats by combined bilateral common carotid artery occlusion and hypotension (42-45 mm Hg). In a separate group of animals, a mild (32 degrees C) post-ischemic hypothermia was induced for 6 h, starting immediately after ischemia. RNA from approximately 500 brain vessels (20-100 microm) extracted by laser-capture microdissection (LCM) microscopy was used to determine the expression of proteoglycans agrin and SPARC mRNAs by quantitative PCR (Q-PCR). Protein expression was determined by immunohistochemistry in adjacent tissue sections. The BBB permeability was assessed using (3)H-sucrose as an in vivo tracer and by examining fibrinogen immunoreactivity in tissue sections. A transient global brain ischemia resulted in a significant (ANOVA, p<0.05; 6 animals/group) reduction in agrin and SPARC mRNAs in LCM-captured brain vessels 24 h after reperfusion. A time-dependent loss of agrin and SPARC from the BM during reperfusion was also observed by immunochemistry. A 6-h post-ischemic hypothermia reduced SPARC and agrin mRNA and protein losses, BBB transfer constant for (3)H-sucrose as well as fibrinogen extravasation 24 h after reperfusion. It is conluded that a transient post-ischemic hypothermia stabilizes brain vessels and reduces BBB disruption in part by preventing proteolytic degradation of regulatory BM constituents, SPARC and agrin.

journal_name

Brain Res

journal_title

Brain research

authors

Baumann E,Preston E,Slinn J,Stanimirovic D

doi

10.1016/j.brainres.2009.02.062

subject

Has Abstract

pub_date

2009-05-07 00:00:00

pages

185-97

eissn

0006-8993

issn

1872-6240

pii

S0006-8993(09)00408-9

journal_volume

1269

pub_type

杂志文章

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Post-ischemic hypothermia attenuates loss of the vascular basement membrane proteins, agrin and SPARC, and the blood-brain barrier disruption after global cerebral ischemia.