PPARβ及 NO 在高糖高胰岛素诱导心肌细胞肥大中的作用

摘要

目的：观察过氧化物酶体增殖物激活受体β（ PPARβ）及一氧化氮（ NO）相关信号通路在高糖高胰岛素（ HGI，25．5 mmol／L葡萄糖＋0．1μmol／L胰岛素）诱导心肌肥大中的作用。方法：体外培养乳鼠心肌细胞，以细胞表面积、蛋白含量和心房钠尿因子（ ANF） mRNA表达作为心肌肥大的指标；利用real－time PCR、Western blot－ting、硝酸还原酶法和分光光度法分别检测mRNA表达、蛋白表达、NO含量和NO合酶（ NOS）活性。结果： HGI诱导心肌细胞出现肥大（P＜0．01），PPARβmRNA和蛋白表达明显降低（P＜0．05），诱导型NOS（iNOS） mRNA和蛋白的表达则升高（P＜0．01），NO含量和NOS活性增加（P＜0．01）。 PPARβ激动剂GW0742能抑制HGI诱导的心肌肥大（P＜0．01），上调PPARβ的表达，降低iNOS的表达，使NOS活性和NO含量恢复正常（P＜0．01）。 PPARβ拮抗剂GSK0660可阻断GW0742对心肌肥大的保护作用，取消其对PPARβ、iNOS mRNA和蛋白表达水平以及NOS活性和NO含量的作用（P＜0．05）。结论：PPARβ下调，激活iNOS－NO信号通路参与高糖高胰岛素诱导心肌肥大过程。%AIM:To investigate the role of peroxisome proliferator-activated receptor β( PPARβ)-nitric oxide (NO) signal pathway in cardiomyocyte hypertrophy induced by high glucose (25.5 mmol/L) and insulin (0.1 μmol/L) ( HGI) .METHODS: The cardiomyocyte hypertrophy was characterized in rat primary cardiomyocytes by measuring the cell surface area, protein content, and the mRNA expression of atrial natriuretic factor (ANF).The mRNA and protein ex-pression were measured by real-time PCR and Western blotting , respectively .The activity of NO synthase ( NOS) and NO content were measured by a reagent kit through ultraviolet spectroscopy .RESULTS:HGI induced profound change of hy-pertrophic morphology , and significantly increased the cell surface area , protein content and mRNA expression of ANF (P<0.01), but decreased the expression of PPARβat mRNA and protein levels (P<0.05).At the same time, the ex-pression of inducible NOS (iNOS) was obviously elevated (P<0.01), which occurred in parallel with the rising NOS ac-tivity and NO concentration (P<0.01).GW0742 (1 μmol/L), a selective PPARβagonist, inhibited the cardiomyocyte hypertrophy induced by HGI ( P<0.01 ) , and up-regulated the expression of PPARβat both mRNA and protein levels . Meanwhile, GW0742 also inhibited the increases in iNOS expression , NOS activity, and NO content induced by HGI , which were abolished by GSK0660 (1 μmol/L), a selective PPARβantagonist (P<0.01).CONCLUSION: PPARβdown-regulation and the following iNOS-NO activation are involved in the cardiomyocyte hypertrophy induced by HGI .