Abstract: Objective To determine the effect of melatonin (MLT) on interleukin-1β(IL-1β)-induced vascular permeability. Methods Human umbilical vein endothelial cells (HUVECs) were exposed to IL-1β with or without MLT at different concentrations, and endothelial cell permeability was assessed by measuring the flux of FITC-dextran across the HUVEC monolayer. To observe the distribution of vascular endothelial cadherin (VE-cadherin) using immunofluorescence staining analysis and determine the expression of VE-cadherin with western blot. Results Treatment with IL-1β(5, 10 and 20ng/ml) increased the relative permeability of HUVECs from 1.5±0.1 to 4.8±0.3, 5.2±0.4 and 9.8±0.8 (P < 0.01); MLT (10 and 100μmol/L) attenuated IL-1β (10ng/ml) induced permeability from 5.2±0.4 to 2.8±0.3 and 2.7±0.3 (P < 0.01). Melatonin improved IL-1β-induced disruption of VE-cadherin adherens junctions. The relative expression of VE-cadherin decreased from 0.91±0.04 in control group to 0.42±0.05 in IL-1β group (P < 0.01) and increased to 0.69±0.04 in MLT group (P < 0.01 compared with IL-1β group), but still lower than control (P < 0.05). Conclusions Our data indicate that MLT may strengthen the barrier integrity of HUVECs through attenuating the change of VE-cadherin.

Key words: Melatonin, Endothelial cell permeability, IL-1β, Vascular endothelial cadherin