Activation of AMPK improves lipopolysaccharide-induced dysfunction of the blood-brain barrier in mice.

Primary Objective: Lipopolysaccharide (LPS) is known to alter the integrity of the blood-brain barrier (BBB) in sepsis, although the underlying mechanism remains unknown. The aim of this study was to elucidate the molecular mechanisms underlying disruption of the BBB in LPS-induced sepsis.
Research Design: Both in vitro and in vivo experiments were designed to test the role of AMP-activated protein kinase (AMPK) in LPS-induced BBB dysfunction.
Methods and Procedures: Human brain microvascular endothelial cells (HBMECs) were cultured. The protein expressions were detected by western blot. BBB integrity was determined by Evans Blue.
Main Outcomes and Results: LPS (1 μg ml(-1)) dramatically increased the permeability of the BBB and the ROS productions, as well as reducing the expression levels of occludin and claudin-5 in cultured HBMECs. Inhibition of NAD(P)H oxidase by apocynin or up-regulation of AMPK reversed the LPS-induced abnormities in HBMECs. In LPS-induced sepsis in mice, it was found that LPS dramatically increased NAD(P)H oxidase protein expressions and ROS productions in the brain and disrupted BBB function assayed by Evans blue staining, which were abolished by AICAR treatment.
Conclusions: It is concluded that AMPK activation improves the functions of the BBB impaired by LPS through suppression of NAD(P)H oxidase-derived ROS in mice.