Li Songtao, Qian Qianyu, Ying Na, Lai Jianfei, Feng Luyan, Zheng Sitong, Jiang Fusheng, Song Qing, Chai Hui, Dou Xiaobing
College of Basic Medicine and Public Health, Zhejiang Chinese Medical University, Hangzhou, China.
Molecular Medicine Institute, Zhejiang Chinese Medical University, Hangzhou, China.
Front Pharmacol. 2020 Nov 30;11:560905. doi: 10.3389/fphar.2020.560905. eCollection 2020.
Salvianolic acid A (Sal A), a natural polyphenol compound extracted from (known as Danshen in China), possesses a variety of potential pharmacological activities. The aim of this study is to determine mechanisms of hepatoprotective effects of Sal A against lipotoxicity both in cultured hepatocytes and in a mouse model of fatty liver disease. High-fat and high-carbohydrate diet (HFCD)-fed C57BL/6J mice were employed to establish hepatic lipotoxicity in a mouse model. Two doses of Sal A were administered every other day via intraperitoneal injection (20 and 40 mg/kg BW, respectively). After a 10-week intervention, liver injury was detected by immunohistochemical and biochemical analyses. For studies, we used HepG2, a human hepatoma cell line, and exposed them to palmitic acid to induce lipotoxicity. The protective effects of Sal A on palmitic acid-induced lipotoxicity were examined in Sal A-pretreated HepG2 cells. Sal A treatments attenuated body weight gain, liver injury, and hepatic steatosis in mice exposed to HFCD. Sal A pretreatments ameliorated palmitic acid-induced cell death but did not reverse effects of HFCD- or palmitate-induced activations of JNK, ERK1/2, and PKA. Induction of p38 phosphorylation was significantly reversed by Sal A in HFCD-fed mice but not in palmitate-treated HepG2 cells. However, Sal A rescued hepatic AMP-activated protein kinase (AMPK) suppression and sirtuin 1 (SIRT1) downregulation by both HFCD feeding in mice and exposure to palmitate in HepG2 cells. Sal A dose-dependently up-regulated p-AMPK and SIRT1 protein levels. Importantly, siRNA silencing of either AMPK or SIRT1 gene expression abolished the protective effects of Sal A on lipotoxicity. Moreover, while AMPK silencing blocked Sal A-induced SIRT1, silencing of SIRT1 had no effect on Sal A-triggered AMPK activation, suggesting SIRT1 upregulation by Sal A is mediated by AMPK activation. Our data uncover a novel mechanism for hepatoprotective effects of Sal A against lipotoxicity both in livers from HFCD-fed mice and palmitic acid-treated hepatocytes.
丹酚酸A（Sal A）是从丹参（在中国被称为Danshen）中提取的一种天然多酚化合物，具有多种潜在的药理活性。本研究的目的是确定Sal A在培养的肝细胞和脂肪肝疾病小鼠模型中对脂毒性的肝保护作用机制。采用高脂高碳水化合物饮食（HFCD）喂养的C57BL/6J小鼠建立小鼠肝脂毒性模型。通过腹腔注射每隔一天给予两剂Sal A（分别为20和40 mg/kg体重）。经过10周的干预后，通过免疫组织化学和生化分析检测肝损伤。对于细胞研究，我们使用人肝癌细胞系HepG2，并将它们暴露于棕榈酸以诱导脂毒性。在Sal A预处理的HepG2细胞中检测Sal A对棕榈酸诱导的脂毒性的保护作用。Sal A处理减轻了暴露于HFCD的小鼠的体重增加、肝损伤和肝脂肪变性。Sal A预处理改善了棕榈酸诱导的细胞死亡，但没有逆转HFCD或棕榈酸诱导的JNK、ERK1/2和PKA激活的作用。在HFCD喂养的小鼠中，Sal A显著逆转了p38磷酸化的诱导，但在棕榈酸处理的HepG2细胞中没有。然而，Sal A挽救了小鼠HFCD喂养和HepG2细胞暴露于棕榈酸导致的肝AMP激活蛋白激酶（AMPK）抑制和沉默调节蛋白1（SIRT1）下调。Sal A剂量依赖性地上调p-AMPK和SIRT1蛋白水平。重要的是，AMPK或SIRT1基因表达的siRNA沉默消除了Sal A对脂毒性的保护作用。此外，虽然AMPK沉默阻断了Sal A诱导的SIRT1，但SIRT沉默对Sal A触发的AMPK激活没有影响，表明Sal A对SIRT1的上调是由AMPK激活介导的。我们的数据揭示了Sal A在HFCD喂养的小鼠肝脏和棕榈酸处理的肝细胞中对脂毒性的肝保护作用的新机制。
