OBJECTIVE: To investigate the relationship between insulin-like growth factor-1 (IGF-1) in the serum and the vascular endothelial function in patients with hypercholesterolemia and the underlying mechanism. METHODS: We examined the flow-mediated arterial diastolic function (FMD), the levels of IGF-1, asymmetric dimethylarginine (ADMA), NO, and the activity of nitric oxide synthase (NOS) in the serum from 25 patients with hypercholesterolemia and from healthy controls. An endothelial cell injury model was established by incubation of the human umbical vein endothelial cells (HUVECs) with oxidized low-density lipoprotein (ox-LDL) for 24 hours. Cells were treated with IGF-1 30 min before ox-LDL treatment. The levels of ADMA, NOS, and NO in the cell supernatant, the activity of dimethylarginine dimethylamine hydrolase (DDAH) in the cell lysate were measured. Beta-galactosidase staining was used to assess the degree of endothelial cell senescence by calculating the senescence rate of cells. RESULTS: Compared with the control group, the FMD, the levels of IGF-1 and NO, and the activity of NOS in the serum from patients with hypercholesterolemia decreased significantly accompanied with a dramatic increase at ADMA level. Multiple linear regression analysis showed that the change in IGF-1 was positively correlated with FMD while the change in ADMA was negatively correlated with FMD. Compared with the control group, ox-LDL treatments significantly decreased the activities of DDAH and NOS, and the level of NO, accompanied with an increase in ADMA. Betagalactosidase staining showed that the senescence rate of cells increased in the ox-LDL group. The effect of ox-LDL on HUVECs was significantly attenuated at the presence of IGF-1. CONCLUSION The decrease in IGF-1 in the peripheral blood may contribute to vascular endothelial dysfunction in patients with hypercholesterolemia. IGF-1 can protect HUVECs against ox-LDL-induced senescence, which is likely involved in the regulation of DDAH/ADMA pathway.
Adult ; Arginine ; analogs & derivatives ; blood ; Case-Control Studies ; Cells, Cultured ; Endothelium, Vascular ; physiology ; Female ; Human Umbilical Vein Endothelial Cells ; cytology ; Humans ; Hypercholesterolemia ; blood ; physiopathology ; Insulin-Like Growth Factor I ; metabolism ; physiology ; Lipoproteins, LDL ; pharmacology ; Male ; Middle Aged ; Nitric Oxide ; blood ; Protective Agents ; metabolism ; Vasodilation ; physiology