Background: Intestinal ischemia/reperfusion (I/R) challenge often results in gut barrier dysfunction and induces distant organ injury. Dexmedetomidine has been shown to protect intestinal epithelial barrier against I/R attack. The present study aims to investigate the degree to which intestinal I/R attack will contribute to gut-vascular barrier (GVB) damage, and to examine the ability of dexmedetomidine to minimize GVB and liver injuries in mice.
Methods: In vivo, intestinal ischemic challenge was induced in mice by clamping the superior mesenteric artery for 45 minutes. After clamping, the mice were subjected to reperfusion for either 2, 4, 6, or 12 hours. Intraperitoneal injection of dexmedetomidine 15, 20, or 25 μg·kg-1 was performed intermittently at the phase of reperfusion. For the in vitro experiments, the challenge of oxygen-glucose deprivation/reoxygenation (OGD/R) was established in cultured vascular endothelial cells, and dexmedetomidine (1 nM) was used to treat the cells for 24 hours. Moreover, in vivo and in vitro, SKL2001 (a specific agonist of β-catenin) or XAV939 (a specific inhibitor of β-catenin) was applied to determine the role of β-catenin in the impacts provided by dexmedetomidine.
Results: The attack of intestinal I/R induced GVB damage. The greatest level of damage was observed at 4 hours after intestinal reperfusion. There was a significant increase in plasmalemma vesicle-associated protein-1 (PV1, a specific biomarker for endothelial permeability) expression (5.477 ± 0.718 vs 1.000 ± 0.149; P < .001), and increased translocation of intestinal macromolecules and bacteria to blood and liver tissues was detected (all P < .001). Liver damages were observed. There were significant increases in histopathological scores, serum parameters, and inflammatory factors (all P < .001). Dexmedetomidine 20 μg·kg-1 reduced PV1 expression (0.466 ± 0.072 vs 1.000 ± 0.098; P < .001) and subsequent liver damages (all P < .01). In vitro, dexmedetomidine significantly improved vascular endothelial cell survival (79.387 ± 6.447% vs 50.535 ± 1.766%; P < .001) and increased the productions of tight junction protein and adherent junction protein (all P < .01) following OGD/R. Importantly, in cultured cells and in mice, β-catenin expression significantly decreased (both P < .001) following challenge. Dexmedetomidine or SKL2001 upregulated β-catenin expression and produced protective effects (all P < .01). However, XAV939 completely eliminated the protective effects of dexmedetomidine on GVB (all P < .001).
Conclusions: The disruption of GVB occurred following intestinal I/R. Dexmedetomidine alleviated I/R-induced GVB impairment and subsequent liver damage.
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