艾塞那肽抑制高糖诱导内皮细胞凋亡的作用机制

Inhibitory mechanism of exenatide on the apoptosis of endothelial cells induced by high glucose

在正常糖浓度（5．5mmol／L）和高糖（33mmol／L）培养的人脐静脉内皮细胞（HUVECs）分别加入不同浓度的艾塞那肽并干预不同时间后，噻唑蓝（MTT）法检测细胞活力，应用流式细胞仪检测细胞早期凋亡率，Western印迹法检测蛋白激酶B（Akt）磷酸化、Bcl-2和Bax蛋白表达水平。结果显示．HUVECs经高糖培养48和72h后，细胞活力明显下降（P〈0．01）。经1、10和100nmol／L艾塞那肽干预48h后，细胞活力明显增加，并呈浓度依赖性（P〈0．01）。与正常糖浓度组比较，高糖组细胞凋亡率升高．Akt磷酸化和Bcl-2蛋白表达水平下降，Bax蛋白表达增加，Bcl-2／Bax比值降低（P〈0．01）。艾塞那肽干预后，细胞凋亡率下降，Akt磷酸化和Bcl-2蛋白表达增加，Bax蛋白表达下降，Bcl-2／Bax比值升高（P〈0．01），而艾塞那肽的作用可被磷酸肌醇3激酶（P13K）抑制剂LY294002所对抗（P〈0．01）。提示艾塞那肽可通过P13k／Akt信号通路调节Bcl-2／Bax蛋白表达来抑制高糖诱导的内皮细胞凋亡，起到保护内皮细胞的作用。

After human umbilical vein endothelial cells （HUVECs） were incubated with various concentrations of exenatide for 24,48, and 72 h under the conditions of 5.5 and 33 nlmol/L glucose, the cell viability was detected by MTT assay. The apoptosis rate of endothelial cells was measured by flow cytometry. Protein kinase B （Akt） phosphorylation, Bcl-2, and Bax protein expression were detected by Western blotting. The results showed that the cell viability was decreased after HUVECs were incubated with high glucose for48 and 72 h （ P〈O. O1 ）. Treatment with 1, 10, and 100 nmol/L exenatide for 48 h significantly increased the cell viability in the presence of high glucose, in a dose-dependent manner （P〈0.01）. High glucose inhibited Akt phosphorylation and Bcl-2 protein expression, stimulated Bax protein expression, with decreased Bcl-2/Bax ratio and increased apoptosis ratio of cells. After treatment with exenatide, the cell apoptosis reduced, Akt phosphorylation and Bcl-2 protein expression increased, and Bax protein expression decreased, with increased Bcl-2/Bax ratio （ P 〈 0. 01 ）. These effects of exenatide on endothelial cell were abrogated by an inhibitor of phosphotylinosital 3 kinase （PI3K） LY294002 （P〈 0. 01 ）, suggesting that the exenatide may regulate Bcl-2/Bax protein expression and inhibit endothelial cell apoptosis induced by high glucose through PI3k/Akt signal pathway, and thus may protect endothelial cells.