Department of Pharmacology, Nantong University Pharmacy College, Nantong, 226001, China.
Department of Pharmacology, Nantong University Pharmacy College, Nantong, 226001, China.
Phytomedicine. 2021 Jan;81:153412. doi: 10.1016/j.phymed.2020.153412. Epub 2020 Nov 18.
Naringenin is naturally isolated from citrus fruits possessing many pharmacological activities. However, little is known about the effect of naringenin on nonalcoholic steatohepatitis (NASH) in the model of metabolic syndrome.
The present study is aimed to investigate the effect of naringenin on NASH in 12-mo-old male ApoE mice and its possible underlying mechanism.
In vivo, 12-mo-old male ApoE mice were administrated with naringenin by intragastric gavage for 12 weeks. At the end of experiment, the blood samples and liver tissues were collected. Metabolic parameters in serum, levels of triglyceride, cholesterol and hydroxyproline, activities of antioxidant enzymes, and content of inflammatory cytokines (TNF-α and IL-6) in liver were examined by corresponding assay kits. Pathological changes in liver were observed by hematoxylin-eosin, oil red O, masson's trichrome, picro-sirius red and senescence β-galactosidase staining. Dihydroethidium was used for detection of reactive oxygen species (ROS). In vitro, AML-12 cells were treated with oleic acid in the presence or absence of naringenin for 24 h. Transfection of SIRT1 siRNA was also conducted in vitro. Lipid accumulation, cellular ROS generation, malondialdehyde content, antioxidant enzyme activities and secretion levels of TNF-α and IL-6 were examined. Both in vivo and in vitro, gene expressions were detected by real-time PCR or western blot.
Naringenin administration improved metabolic parameters, suppressed hepatic steatosis, regulated expression of genes involved in lipid metabolism (FASN, SCD1, PPARα and CPT1α), reduced hepatic fibrosis and cell senescence, inhibited hepatic inflammation as evidenced by the decreased macrophage recruitment and content of TNF-α and IL-6, and reduced hepatic oxidative stress by suppressing ROS generation and normalizing activities of antioxidant enzymes. Notably, naringenin administration increased hepatic SIRT1 protein expression and activity along with the increased deacetylation of liver kinase B1 (LKB1), PGC1α and NF-κB. In vitro study, the benefits of naringenin on lipid accumulation, oxidative stress and inflammation were diminished by SIRT1 siRNA transfection.
These results indicate that naringenin administration may be a potential curative therapy for NASH treatment and the activation of hepatic SIRT1-mediated signaling cascades is involved in its beneficial effects.
柚皮素是从柑橘类水果中天然分离出来的，具有许多药理活性。然而，关于柚皮素对代谢综合征模型中非酒精性脂肪性肝炎（NASH）的影响知之甚少。
本研究旨在探讨柚皮素对 12 月龄雄性 ApoE 小鼠 NASH 的作用及其可能的机制。
体内实验中，12 月龄雄性 ApoE 小鼠给予柚皮素灌胃 12 周。实验结束时，采集血样和肝组织。采用相应试剂盒检测血清代谢参数、甘油三酯、胆固醇和羟脯氨酸水平、抗氧化酶活性以及肝组织中炎症细胞因子（TNF-α和 IL-6）含量。采用苏木精-伊红、油红 O、Masson 三色、苦味酸天狼猩红和衰老β-半乳糖苷酶染色观察肝组织病理变化。二氢乙啶用于检测活性氧（ROS）。体外实验中，AML-12 细胞用油酸处理，同时或不同时用柚皮素处理 24 h。体外还进行了 SIRT1 siRNA 转染。检测脂滴堆积、细胞 ROS 生成、丙二醛含量、抗氧化酶活性以及 TNF-α和 IL-6 的分泌水平。体内外实验均采用实时 PCR 或 Western blot 检测基因表达。
柚皮素给药改善了代谢参数，抑制了肝脂肪变性，调节了参与脂质代谢的基因表达（FASN、SCD1、PPARα和 CPT1α），减少了肝纤维化和细胞衰老，抑制了肝炎症，表现为巨噬细胞募集和 TNF-α和 IL-6 含量减少，并通过抑制 ROS 生成和正常化抗氧化酶活性降低了肝氧化应激。值得注意的是，柚皮素给药增加了肝 LKB1、PGC1α 和 NF-κB 的去乙酰化，从而增加了肝 SIRT1 蛋白表达和活性。体外研究表明，SIRT1 siRNA 转染减弱了柚皮素对脂滴堆积、氧化应激和炎症的作用。
这些结果表明，柚皮素给药可能是治疗 NASH 的潜在治疗方法，肝 SIRT1 介导的信号级联的激活参与了其有益作用。
