School of Basic Medical Science, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
Public Laboratory Platform, School of Basic Medical Science, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
J Ethnopharmacol. 2021 May 10;271:113853. doi: 10.1016/j.jep.2021.113853. Epub 2021 Jan 22.
Ophiopogonin D (OP-D) is a steroidal saponin extracted from Ophiopogon japonicus (Thunb.) Ker Gawl. (Liliaceae), that has been traditionally used to treat cough, sputum, and thirst in some Asian countries. Recently, various pharmacological roles of OP-D have been identified, including anti-inflammatory, cardioprotective, and anti-cancer effects. However, whether OP-D can prevent diabetic myocardial injury remains unknown.
In this study, we aimed to observe the effects of OP-D on the diabetic myocardium.
Leptin receptor-deficient db/db mice were used as an animal model for type 2 diabetes. The effects of OP-D on blood glucose, blood lipids, myocardial ultrastructure, and mitochondrial function in mice were observed after four weeks of intragastric administration. Palmitic acid was used to stimulate cardiomyocytes to establish a myocardial lipotoxicity model. Cell apoptosis, mitochondrial morphology, and function were observed.
Blood glucose and blood lipid levels were significantly increased in db/db mice, accompanied by myocardial mitochondrial injury and dysfunction. OP-D treatment reduced blood lipid levels in db/db mice and relieved mitochondrial injury and dysfunction. OP-D inhibited palmitic acid induced-mitochondrial fission and dysfunction, reduced endogenous apoptosis, and improved cell survival rate in H9C2 cardiomyocytes. Both in vivo and in vitro models showed increased phosphorylation of DRP1 at Ser-616, reduced phosphorylation of DRP1 at Ser-637, and reduced expression of fusion proteins MFN1/2 and OPA1. Meanwhile, immunofluorescence co-localization analysis revealed that palmitic acid stimulated the translocation of DRP1 protein from the cytoplasm to the mitochondria in H9C2 cardiomyocytes. The imbalance of mitochondrial dynamics, protein expression, and translocation of DRP1 were effectively reversed by OP-D treatment. In isolated mice ventricular myocytes, palmitic acid enhanced cytoplasmic Ca levels and suppressed contractility in ventricular myocytes, accompanied by activation of calcineurin, a key regulator of DRP1 dephosphorylation at Ser-637. OP-D reversed the changes caused by palmitic acid.
Our findings indicate that OP-D intervention could alleviate lipid accumulation and mitochondrial injury in diabetic mouse hearts and palmitic acid-stimulated cardiomyocytes. The cardioprotective effect of OP-D may be mediated by the regulation of mitochondrial dynamics.
麦冬皂苷 D（OP-D）是从麦冬（百合科）中提取的甾体皂苷，传统上用于治疗一些亚洲国家的咳嗽、痰和口渴。最近，人们发现 OP-D 具有多种药理作用，包括抗炎、心脏保护和抗癌作用。然而，OP-D 是否能预防糖尿病心肌损伤尚不清楚。
本研究旨在观察 OP-D 对糖尿病心肌的影响。
使用瘦素受体缺陷型 db/db 小鼠作为 2 型糖尿病动物模型。观察 OP-D 灌胃 4 周后对小鼠血糖、血脂、心肌超微结构和线粒体功能的影响。用棕榈酸刺激心肌细胞建立心肌脂肪毒性模型，观察细胞凋亡、线粒体形态和功能。
db/db 小鼠血糖和血脂水平明显升高，伴有心肌线粒体损伤和功能障碍。OP-D 治疗降低了 db/db 小鼠的血脂水平，并缓解了线粒体损伤和功能障碍。OP-D 抑制了棕榈酸诱导的线粒体裂变和功能障碍，减少了内源性细胞凋亡，提高了 H9C2 心肌细胞的存活率。在体内和体外模型中，均观察到 DRP1 丝氨酸 616 位点磷酸化增加，DRP1 丝氨酸 637 位点磷酸化减少，以及融合蛋白 MFN1/2 和 OPA1 的表达减少。同时，免疫荧光共定位分析显示，棕榈酸刺激 H9C2 心肌细胞中 DRP1 蛋白从细胞质向线粒体转位。OP-D 治疗有效逆转了线粒体动力学、DRP1 蛋白表达和转位的失衡。在分离的小鼠心室肌细胞中，棕榈酸增强了细胞质 Ca 水平并抑制了心室肌细胞的收缩力，同时激活了钙调神经磷酸酶，这是 DRP1 丝氨酸 637 去磷酸化的关键调节因子。OP-D 逆转了棕榈酸引起的变化。
我们的研究结果表明，OP-D 干预可减轻糖尿病小鼠心脏和棕榈酸刺激的心肌细胞中脂质堆积和线粒体损伤。OP-D 的心脏保护作用可能是通过调节线粒体动力学来实现的。
