Oxymatrine reduces hepatic lipid synthesis in rat model of nonalcoholic steatohepatitis by regulating Sirt1/AMPK and LXR/Plin2/SREBP-1c pathways

Nonalcoholic Steatohepatitis (NASH) is a common liver disease with limited treatment options. Oxymatrine (OMT) has been reported to treat liver diseases effectively. This study aims to explore the mechanisms of OMT in NASH. Male Sprague-Dawley rats were fed a high-fat and high-sucrose diet and hepatocytes were stimulated with oleic acid (OA) to establish NASH models, then, NASH models were intervened with OMT. In vivo, liver injury and lipid accumulation extents were evaluated by serum and liver biochemical indexes, and histological analysis. In vitro, cell viability and lipid accumulation degrees were measured. Additionally, the relationships between perilipin 2 (Plin2) and liver X-activated receptor alpha (LXRα) as well as Plin2 and sterol regulatory element binding protein-1c (SREBP-1c), sirtuin 1 (Sirt1)/adenosine 5‘-monophosphate-activated protein kinase (AMPK) pathway-, liver X-activated receptor (LXR)/Plin2/SREBP-1c pathway- and lipid synthesis-related proteins were detected both in vivo and in vitro. Finally, Sirt1 was knocked down in hepatocytes. OMT not only reduced serum alanine aminotransferase activity and triglyceride content, liver triglyceride and free fatty acid levels in NASH rats, but also improved hepatic injury and lipid accumulation. In vitro, OMT enhanced viability, and downregulated lipid accumulation in OA-induced hepatocytes. Both in vivo and in vitro results revealed Plin2 directly interacted with LXRα and SREBP-1c, and OMT activated Sirt1/AMPK pathway but inhibited the expressions of LXR/Plin2/SREBP-1c pathway and lipid synthesis (acetyl-CoA carboxylase, fatty acid synthase, stearoyl-Coenzyme A desaturase 1) related proteins in NASH models. Importantly, Sirt1 knockdown reversed the protective effects of OMT in OA-stimulated hepatocytes. OMT may reduce hepatic lipid synthesis in NASH by activating the Sirt1/AMPK pathway and inhibiting the LXR/Plin2/SREBP-1c pathway, suggesting that OMT may be a promising strategy for treating NASH.