Antagonism and mechanism of melatonin against H2O2-induced injury of vascular endothelial cells

AIM:To study the effect of melatonin (MLT) on normal vascular endothelial cells as well as the antagonism and mechanism of MLT against H2O2-induced injury of vascular endothelial cells. METHODS: Cultured human umbilical vein endothelial cells (HUVECs) were treated with MLT (125, 250 and 500 μmol/L) for 2, 4 and 6 h and the survival rate of HUVECs was detected with thiazole blue (MTT) assay. Injury of HUVECs was induced by H2O2 (300 μmol/L) treatment; serial concentrations of MLT (125, 250 and 500 μmol/L) was applied for 2, 4 and 6 h. The survival rate, adhesion capacity, SOD activity, LDH release and NO-2 concentration of HUVECs were detected. RESULTS: After treatment with MLT (125, 250 and 500 μmol/L) for 2, 4 and 6 h, the survival rate of HUVECs were not significantly altered. The survival rate, adhesion capacity and SOD activity of H2O2-treated HUVECs improved and LDH release was reduced significantly after MLT treatment (P<0.01). In addition, MLT treatment significantly increased the production of NO in cell culture medium compared with H2O2 treatment alone (P<0.01). Compared with the other concentrations observed, MLT concentration of 500 μmol/L produced a more significant antagonistic effect. CONCLUSION: The safe concentration range of MLT is broad because no significant difference is observed in the effects on the survival rate of HUVECs treated with different concentrations of MLT (125, 250 and 500 μmol/L). MLT treatment may antagonize H2O2-induced injury of cultured HUVECs via its antioxidant capacity and promotion of NO synthesis.