Hypolipidemic effect of ethanol extract from Chimonanthus nitens Oliv. leaves in hyperlipidemia rats via activation of the leptin/JAK2/STAT3 pathway

Abstract

Background: This study aims to explore the protective role of ethanol extract from Chimonanthus nitens Oliv. leaf (COE) in hyperlipidemia via the leptin/Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway. Methods: Male Sprague‒Dawley rats were randomly divided into 6 groups (n = 8): normal-fat diet (NMD), high-fat diet (HFD), HFD treated with simvastatin (SIM, 5 mg/kg/day), and HFD treated with COE (40, 80, 160 mg/kg/day). Lipid parameters, oxidative stress factors, serum leptin, body weight, hepatic wet weight and liver index were measured. Proteins in the leptin/JAK2/STAT3 pathway in liver tissues were determined using western blotting. Additionally, the expression levels of cytochrome P450 family 7 subfamily A member 1 (CYP7A1) and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) were quantified using western blotting and quantitative real-time polymerase chain reaction (qPCR). Results: COE decreased HFD-induced increases in body weight, hepatic wet weight and the liver index. HFD-induced hyperlipidemia and oxidative stress were observed in rat serum and livers. Additionally, COE repressed these two symptoms in rats fed a HFD. Moreover, COE caused CYP7A1 upregulation and HMGCR downregulation in HFD-fed rats. Mechanistically, COE induced the expression of leptin receptor (OB-Rb) and JAK2 and STAT3 phosphorylation in HFD-treated rats. Conclusion: COE activates the leptin/JAK2/STAT3 pathway, leading to an improvement in liver function and lipid metabolism and ultimately alleviating hyperlipidemia in rats. Therefore, COE may be a potential hypolipidemic drug for the treatment of hyperlipidemia.