Objective: To investigate the effect of maslinic acid (MA) on isoproterenol (ISO)-induced myocardial fibrosis in mice. Methods: ISO was used to induce myocardial fibrosis in adult male C57BL/6 mice, and MA was administered for two weeks to detect the effects of MA on cardiac function and fibrosis. Molecular changes of fibrosis markers and signaling pathways were detected by RT-PCR and western blotting. Phosphate buffer saline (PBS), PBS+SB203580 (p38 MAPK inhibitor), PBS+MA, ISO, ISO+SB203580, ISO+MA were added to the primary cultured rat fibroblasts. Cells were collected after 48 h for subsequent detection. Results: In this study, the mouse model of myocardial fibrosis was successfully established. The left ventricular faction shortening (FS) and maximum rate of rise and maximum rate of fall of pressure in left ventricular chamber (±dp/dt) of the ISO+MA group were significantly higher than those of the ISO group ((35.1±1.8)% vs (28.5±2.6)%, (7 256±153) mmHg/s vs (6 402±240) mmHg/s, (7 156±163) mmHg/s vs (6 319±219) mmHg/s, all P<0.05). The levels of interstitial and perivascular collagen deposition in the ISO+MA group were higher than those in the ISO group (P<0.05), the relative mRNA levels of COL-1, COL-3 and TGF-β in the ISO+MA group were significantly lower than those in the ISO group, with the relative expression levels of 1.70±0.24 vs 3.69±0.34, 1.72±0.56 vs 4.84±0.82, 1.52±0.19 vs 2.64±0.29, respectively (all P<0.05). The phosphorylation levels of p38 MAPK, Smad3 and protein expression level of TGF-β1 in ISO+MA group were lower than those in ISO group (relative expression levels were 1.67±0.35 vs 2.61±0.58, 1.68±0.23 vs 2.52±0.19,1.56±0.15 vs 2.48±0.26, respectively, all P<0.05). The results of in vitro cell experiments showed that the mRNA levels of COL-1, COL-3 and TGF-β in the SB203580 and MA groups were significantly lower than those in the ISO group (relative expression levels were 2.25±0.51, 2.16±0.48 vs 5.29±1.21; 1.58±0.34, 1.69±0.29 vs 4.97±1.32; 1.41±0.31, 1.55±0.38 vs 3.53±0.56, respectively, all P<0.05). The phosphorylation levels of p38 MAPK and Smad3 in the SB203580 MA groups was significantly lower than those in the ISO group, and the protein expression level of TGF-β1 was lower than that in the ISO group (1.81±0.18, 1.77±0.16 vs 2.56±0.32; 1.85±0.21, 1.81±0.17 vs 2.48±0.37; 1.84±0.24, 1.72±0.17 vs 2.52±0.29, all P<0.05). Conclusion: Maslinic acid can inhibit the phosphorylation of p38 MAPK, thereby preventing the canonical TGF-β1/Smads fibrosis signaling pathway to achieve an anti-fibrosis role.
目的： 探讨山楂酸（MA）对异丙肾上腺素（ISO）诱导的小鼠心肌纤维化的影响。 方法： 使用ISO诱导成年雄性C57BL/6小鼠心肌纤维化，MA给药2周，检测MA对心功能和纤维化的影响。RT-PCR和免疫印迹检测纤维化标志物和信号通路分子变化。将原代培养的大鼠成纤维细胞中分别加入磷酸缓冲盐溶液（PBS）、PBS+p38 MAPK抑制剂（SB203580）、PBS+MA、ISO、ISO+SB203580、ISO+MA。48 h后收集细胞进行后续检测。 结果： 本研究成功制备心肌纤维化小鼠模型，ISO+MA组的左心室短轴缩短率（FS）和左心室内压最大上升速率和最大下降速率（±dp/dt）显著高于ISO组[分别为（35.1±1.8）%比（28.5±2.6）%、（7 256±153）mmHg/s比（6 402±240）mmHg/s、（7 156±163）mmHg/s比（6 319±219）mmHg/s，P<0.05]；ISO+MA组间质和血管周胶原沉积程度高于ISO组（P<0.05），ISO+MA组的COL-1、COL-3和TGF-β mRNA相对水平显著低于ISO组（1.70±0.24比3.69±0.34、1.72±0.56比4.84±0.82、1.52±0.19比2.64±0.29，P<0.05）；ISO+MA组的p38 MAPK和Smad3的磷酸化水平和TGF-β1蛋白表达水平低于ISO组（1.67±0.35比2.61±0.58、1.68±0.23比2.52±0.19、1.56±0.15比2.48±0.26，P<0.05）；体外细胞实验结果显示，p38 MAPK特异性抑制剂（SB203580）组和MA组的COL-1、COL-3、TGF-β mRNA水平均显著低于ISO组（分别为2.25±0.51，2.16±0.48比5.29±1.21；1.58±0.34，1.69±0.29比4.97±1.32；1.41±0.31，1.55±0.38比3.53±0.56，P<0.05）；SB203580组和MA组的p38 MAPK、Smad3的磷酸化水平均显著低于ISO组，TGF-β1的蛋白表达低于ISO组（分别为1.81±0.18，1.77±0.16比2.56±0.32；1.85±0.21，1.81±0.17比2.48±0.37；1.84±0.24，1.72±0.17比2.52±0.29，P<0.05）。 结论： MA可抑制p38 MAPK的磷酸化，进而抑制经典的TGF-β1/Smads纤维化信号通路来发挥抗纤维化的作用。.
Keywords: Maslinic acid; Myocardial fibrosis; TGF-β1 signal pathway; p38 MAPK.