Abstract
BackgroundEmodin (EM) is one of bioactive components extracted from Rheum palmatum L. (Dahuang), which possesses numerous pharmacological activities including hypolipidemic effect. However, the potential action of EM on hyperlipidemia (HLP) remains unclear. Here, the theraputic effect of EM against HLP were investigated.MethodsIn this study, the hypolipidemic properties of EM were evaluated using high-cholesterol diet (HCD)-stimulated zebrafish larvae model. The body weight, body length and body mass index (BMI) was measured. The total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) as well as the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were detected by corresponding assay kits. Tg (flil: eGFP) zebrafish were utilized to observe vascular cholesterol accumulation and Tg (mpx: eGFP) zebrafish to visualize and quantify neutrophil inflammation. The hepatic lipid deposition and hepatic histopathology were analyzed by Oil red O staining and H&E staining, respectively. Finally, the underlying mechanism of EM were investigated using real-time quantitative PCR (RT-qPCR) analysis to assess the gene levels of adenosine monophosphate-activated protein kinase alpha (AMPKα), sterol regulatory element binding protein 2 (SREBP-2), proprotein convertase subtilisin kexin 9 (PCSK9), low-density lipoprotein receptor (LDLR), 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR), adenosine triphosphate binding cassette transporter A1 (ABCA1) and adenosine triphosphate binding cassette transporter G1 (ABCG1).ResultsOur data indicated that EM reduced obesity of zebrafish as evidenced by the decrease in body weight, body length and BMI. EM significantly reduced TC, TG, and LDL-C, and increased HDL-C contents. Moreover, it displayed a prominent inhibitory effect on blood cholesterol accumulation, hepatic lipid accumulation, and neutrophil inflammation in vascular site. Additionally, EM improved the liver function through decreasing ALT and AST levels of zebrafish with HCD-induced hepatosteatosis. Further investigation showed that EM treatment attenuated lipid accumulation via upregulating the expression of AMPKα, LDLR, ABCA1 and ABCG1, and downregulating the expression of SREBP-2, PCSK9 and HMGCR.ConclusionTo conclude, EM alleviated lipid metabolism disorder symptoms caused by HCD via modulating AMPK/SREBP-2/PCSK9/LDLR pathway in larvae, suggesting that EM may be developed into hypolipidmic agent for treating lipid metabolism related diseases.
Regulation of hepatic cholesterol metabolism in humans: stimulatory effects of cholestyramine on HMG-CoA reductase activity and low density lipoprotein receptor expression in gallstone patients.
