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[Influence of lipopolysaccharide on the permeability of rat brain microvascular endothelial cells and the molecular mechanism].

OBJECTIVE
To study the influence of lipopolysaccharide (LPS) on the permeability of rat brain microvascular endothelial cells (BMECs) and possible molecular mechanism.


METHODS
Monolayers of primary rat BMECs were separated and cultured, and then treated with (LPS group) or without LPS (control group). The barrier integrity was measured by transendothelial electrical resistance (TEER) assay. The degrees of RhoA activation were determined by Pull-down assay. The expression levels of p115RhoGEF, zonula occludens-1 (ZO-1), occludin and claudin-5 proteins were detected by Western blot analysis.


RESULTS
The average TEER values of rat BMECs in the LPS group were 108.3±4.2 Ω•cm2 and 85.4±2.5 Ω•cm2 respectively 3 and 12 hrs after LPS treatment, which were significantly lower than that in the control group (159.0±8.6 Ω•cm2). Compared with the control group, the activity of RhoA started to increase 5 minutes after LPS treatment, and the expression of p115RhoGEF protein started to increase 1 hr after LPS treatment and the cellular protein levels of ZO-1, occludin and claudin-5 decreased significantly 3 hrs after LPS treatment in the LPS group (P<0.05).


CONCLUSIONS
LPS may activate the p115RhoGEF/RhoA pathway and decrease protein expression of ZO-1, occludin and claudin-5, resulting in an increased permeability of rat BMECs.