PPARγ介导卡托普利改善高糖诱导血管内皮细胞胰岛素抵抗的作用

Improvement effect of captopril on insulin resistance mediated by PPARγ in vascular endothelial cells

目的研究卡托普利(captopril,Cap)对高糖(high glucose,HG,33 mmol·L-1)诱导的人脐静脉内皮细胞(human umbilical vein endothelium cells,HUVECs)胰岛素抵抗(insulin resistance,IR)的作用及机制。方法首先观察Cap对HG(33 mmol·L-1)诱导的HUVECs IR的改善作用。实验随机分为5组,即正常对照(Control)组、IR组、IR+CapⅠ(1×10-6mol·L-1)组、IR+CapⅡ(1×10-5mol·L-1)组、IR+CapⅢ(1×10-4mol·L-1)组。其次证实Cap改善HG(33mmol·L-1)诱导HUVECs IR的作用是由PPARγ介导。实验随机分为6组,即Control组、IR组、IR+Cap(1×10-5mol·L-1)组、PPARγ抑制剂GW9662(PI,1.0μmol·L-1)组、IR+PPARγ抑制剂(IR+PI,1.0μmol·L-1)组、IR+Cap+PPARγ抑制剂(IR+Cap+PI,1.0μmol·L-1)组,除Control组和PI组外,所有各组先用含33 mmol·L-1葡萄糖的DMEM培养48 h,Cap各组再加不同浓度的Cap处理4 h,最后胰岛素(100 nmol·L-1)处理30 min,抑制剂组再加抑制剂(1.0μmol·L-1)处理1 h,最后进行指标检测。结果 IR组NO水平明显降低、ET-1含量明显升高,提示细胞已产生IR,但PPARγmRNA和蛋白表达水平与Control组相比差异无统计学意义(P>0.05);Cap呈浓度依赖性逆转HG诱导NO和ET-1水平的改变,明显增加磷酸化PPARγ(PPPARγ)水平,说明其可明显改善HG诱导的IR,但对PPARγmRNA和蛋白表达水平无明显影响(vs IR,P>0.05);加PI处理后,Cap改善IR的作用完全取消,提示Cap改善IR的作用是由PPARγ介导。结论Cap可通过PPARγ介导改善高糖所致血管内皮细胞IR,其机制可能与PPARγ表达水平无关,而与PPARγ激活有关。

Aim To investigate the role of captopril in insulin resistance of endothelial cells induced by high glucose. Methods 1. Improvement effect of captopril on insulin resistance in HUVECs was observed. The HUVECs were seeded in a 6-well plate and were randomly divided into 5 groups,namely,control group,IR group,IR together with different Cap concentrations（ low,medium and high concentration）,respectively.2. Improvement effect of Cap on insulin resistance was mediated by PPARγ in HUVECs. HUVECs were randomly divided into 6 groups,namely,control group,control ＋ PPARγ inhibitor（ PI）（ 1. 0 μmol ·L^-1）group,IR group,IR ＋ PI（ 1. 0 μmol·L^-1） group,IR ＋Cap（ 1 × 10^- 5mol·L- 1） group,and IR ＋ Cap ＋ PI（ 1. 0 μmol·L^-1） group. All indicators were detected.Results After HUVECs were incubated with media containing 33 mmol·L- 1of glucose for 48 h,the NO levels were significantly decreased while ET-1 levels were significantly elevated,showing a significant difference between IR group and control group（ P〈 0. 01）.The expression levels of PPARγ mRNA and its protein were somewhat up-regulated,but there was no significant difference between IR group and control group（ P 〈0. 05）. When the HUVECs in IR group were treated with DMEM containing glucose（ 33 mmol ·L^-1） for48 h and insulin for 30 min,the expression levels of PPARγ mRNA and its protein in Cap groups were similar to those in the IR group,and there was no significant difference between the two groups（ P 〉0. 05）;however, the expression levels of phosphorylated-PPARγ protein in Cap groups were increased compared with IR group（ P〈 0. 05）. The levels of NO were significantly increased whereas the levels of ET-1 were decreased in Cap groups,which had significant differences compared with IR group（ P〈 0. 05）. Nonetheless,pre-treating with GW9662,a PPARγ inhibitor,the improvement effects of Cap were markedly abolished. Conclusions Captopril could improve high glucose-induced insulin resistance of endothelial cells mediated by PPARγ,and the underlying mechanisms are related to the activation of PPARγ,rather than its expression.