Melatonin inhibits high glucose-induced ox-LDL/LDL expression and apoptosis in human umbilical endothelial cells

Cardiovascular disease (CVD) is one of the major cause of mortality in diabetic patients. Evidence suggests that hyperglycemia in diabetic patients contributes to increased risk of CVD. This study is to investigate the therapeutic effects of melatonin on glucose-treated human umbilical vein endothelial cells (HUVEC) and provide insights on the underlying mechanisms.

Cell viability was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Reactive oxygen species (ROS) and membrane potential was detected using 2',7'-dichlorofluorescein diacetate and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine iodide (JC-1) dye staining, respectively. While, cell apoptosis was determined by Annexin-V staining and protein expression was measured using Western blot.

Our results suggested that melatonin inhibited glucose-induced ROS elevation, mitochondria dysfunction and apoptosis on HUVEC. Melatonin inhibited glucose-induced HUVEC apoptosis via PI3K/Akt signaling pathway. Activation of Akt further activated BcL-2 pathway through upregulation of Mcl-1 expression and downregulation Bax expression in order to inhibit glucose-induced HUVEC apoptosis. Besides that, melatonin promoted downregulation of oxLDL/LOX-1 in order to inhibit glucose-induced HUVEC apoptosis.

In conclusion, our results suggested that melatonin exerted vasculoprotective effects against glucose-induced apoptosis in HUVEC through PI3K/Akt, Bcl-2 and oxLDL/LOX-1 signaling pathways.