Objective: To investigate the effect of biflavonoid 4'-O-methylochnaflavone (MF) on palmitic acid-induced endothelial dysfunction in rat cavernous endothelial cells (RCECs).
Methods: The isolated RCECs were commercially available and randomly divided into four groups: normal+BSA group (NC group), palmitic acid (PA) group, MF group, and icariside Ⅱ (ICA Ⅱ) group. The protein expression levels of protein kinase B (PKB/AKT) and endothelial nitric oxide synthase (eNOS) in each group were evaluated via Western blotting. The differences in the intracellular nitric oxide of RCECs treated by MF or ICA Ⅱ were detected by DAF-FM DA that served as a nitric oxide fluorescent probe. Effects of MF and ICA Ⅱ on cell proliferation of PA-stimulated RCECs were determined via CCK-8 assay.
Results: The content of nitric oxide in RCECs was significantly increased after the treatment of MF and ICA Ⅱ in comparison with the NC group (P < 0.05). Moreover, compared with ICA Ⅱ group, MF demonstrated a more obvious effect in promoting nitric oxide production (P < 0.05). Compared with the NC group, the expression levels of eNOS and AKT in the PA group were significantly decreased, indicating that a model for simulating the high-fat environment in vitro was successfully constructed (P < 0.05). Meanwhile, the intervention of MF and ICA Ⅱ could effectively increase the expression of eNOS and AKT, suggesting that MF and ICA Ⅱ could promote the recovery of endothelial dysfunction caused by high levels of free fatty acids (P < 0.05). The results of CCK-8 assays showed that PA could significantly reduce the proli-feration ability of RCECs (P < 0.05). Furthermore, the decreased cell viability induced by PA was significantly elevated by treatment with ICA Ⅱ and MF (P < 0.05).
Conclusion: In RCECs, MF and ICA Ⅱ could effectively increase the content of nitric oxide. The down-regulation of the expression of proteins associated with the AKT/eNOS pathway after PA treatment revealed that this pathway was involved in the development of endothelial dysfunction, which could be effectively reversed by MF and ICA Ⅱ. In addition, the cell proliferation ability was significantly decreased following PA treatment, but MF and ICA Ⅱ could restore the above changes. Overall, biflavonoid MF has an obvious repairing effect on PA-stimulated endothelial dysfunction.
目的: 探讨双黄酮类药物4′-甲基醚金连木黄酮(4′-O-methylochnaflavone, MF)对棕榈酸诱导的大鼠阴茎海绵体内皮细胞(rat cavernous endothelial cells, RCECs)功能障碍的影响。
方法: 将RCECs随机分为4组，分别为正常+牛血清白蛋白组(NC组)、棕榈酸(palmitic acid，PA)组、MF治疗组、淫羊藿次苷Ⅱ(icasiside Ⅱ，ICA Ⅱ)治疗组。采用蛋白印迹实验检测各组细胞的蛋白激酶B(protein kinase B, PKB/AKT)和内皮型一氧化氮合酶(endothelial nitric oxide synthase，eNOS)蛋白表达水平，使用一氧化氮荧光探针检测MF以及ICA Ⅱ对RCECs内一氧化氮含量的影响，使用CCK-8试剂盒检测MF、ICA Ⅱ对PA诱导后的RCECs增殖能力的影响。
结果: 与NC组相比，MF组、ICA Ⅱ组处理后细胞内一氧化氮含量显著增加(P < 0.05)，MF组的效果优于ICA Ⅱ组(P < 0.05)。与NC组相比，PA组的eNOS和AKT蛋白表达水平明显降低，提示成功构建了用于模拟高脂环境的体外RCECs内皮功能障碍模型(P < 0.05)。MF组干预后能够有效提高eNOS、AKT的表达水平，表明MF可促进恢复游离脂肪酸造成的内皮细胞损伤(P < 0.05)。CCK-8增殖实验显示PA显著降低RCECs的增殖数量(P < 0.05)，而给予MF、ICA Ⅱ治疗后细胞增殖能力得到显著恢复(P < 0.05)。
结论: 在RCECs中，MF与ICA Ⅱ能够有效增加细胞内一氧化氮含量，PA处理后AKT/eNOS通路的下调揭示其参与内皮细胞损伤的发生、发展，而MF的干预能够有效逆转上述变化，此外，PA诱导下RCECs的细胞增殖能力明显下降，而MF与ICA Ⅱ干预能够恢复上述变化。双黄酮类药物MF对PA诱导的RCECs细胞功能障碍有一定程度的修复作用。
Keywords: Endothelial dysfunction; Nitric oxide synthase; Palmitic acid; Signal transduction.