高糖对缺氧/复氧乳鼠心肌细胞GLP-1受体表达影响及机制研究

目的 探索高糖对缺氧/复氧（H/R）乳鼠心肌细胞胰高血糖样肽-1受体（GLP-1R）表达的影响及其分子机制。 方法 培养乳鼠心肌细胞建立高糖H/R损伤模型，随机将心肌细胞分为对照（正常血糖）组、正常血糖＋H/R组、正常血糖＋GLP-1激动剂（Exentin-4）处理组、高糖组、高糖＋H/R组、高糖＋H/R＋Exentin-4处理组。Western blot观察高糖H/R后GLP-1R表达变化情况。RT-PCR和Western blot观察各组细胞H/R损伤的氧化应激标志物NOX4、p22phox表达变化；Western blot检测高糖条件下蛋白激酶C（PKC）表达，并观察PKC激动剂PMA和或PKC抑制剂Go 6983处理后GLP-1R表达及NOX4、p22phox表达变化。 结果 正常血糖条件下，H/R后心肌细胞氧化应激加重（P<0.05），Exendin-4降低氧化应激损伤（P<0.05）；与正常血糖H/R组相比，高糖H/R组氧化应激损伤加重（P<0.05），而Exendin-4对高糖条件下抗氧化应激作用无明显改善。与正常血糖组相比，高糖组PKC表达升高（P<0.05），参与心肌细胞GLP-1R表达下降，抑制PKC活性可部分恢复Exendin-4高糖条件下抗氧化应激作用（P<0.05）。 结论 高糖条件下GLP-1R表达下降，PKC参与其表达下降，抑制PKC活性可部分恢复Exendin-4高糖条件下抗氧化应激作用。

Expression of GLP-1R and related mechanism in rat cardiomyocytes with high glucose conditions

AIM To explore the expression of glucagon-like peptide-1 receptor (GLP-1R) and related molecular mechanism on hypoxic reoxygenation injury of cardiomyocytes in mice under high glucose conditions. METHODS Hypoxic-reoxygenation model was established by cultured mice cardiomyocytes with high glucose and non-high glucose. The experiments were divided into six groups: group. control group with normal glucose (NG)、NG+ Hypoxic-reoxygenation (H/R)、NG+H/R+Exendin-4、control group with high glucose (HG)、HG+H/R、HG+H/R+Exendin-4. The expression GLP-1R was observed by Western blot. The oxidative stress marker of NOX4 and p22phox was observed by Western blot and RT-PCR. And exogenous GLP-1R agonist exendin-4 and PKC agonist (PMA) and PKC inhibitor (Go 6983) was treated according to the experimental groups to detect the expression changes of GLP-1R and the expression changes of oxidative stress marker NOX4 and p22phox. RESULTS Compared to NG+H/R group, Exendin-4 reduced the oxidative stress injury（P<0.05）, but the anti-oxidative stress effect of GLP-1 on cardiomyocytes of mice was significantly reduced in high-glucose culture. The overexpression of PKC in mice cardiomyocytes of high-glucose culture down-regulated the expression of GLP-1R（P<0.05）. After inhibition of PKC by PKC inhibitor Go 6983, the protective effect of GLP-1 on mice cardiomyocytes of high-glucose culture could be partially restored（P<0.05）. CONCLUSION Under high glucose conditions, PKC reduces the expression of GLP-1R on hypoxic reoxygenation injury of cardiomyocytes in mice and the antioxidant stress effect of GLP-1 is partly restored by down-regulating the active of PKC.