The GPR40 novel agonist SZZ15-11 improves non-alcoholic fatty liver disease by activating the AMPK pathway and restores metabolic homeostasis in diet-induced obese mice

Aim: Non-alcoholic fatty liver is the most common cause of chronic liver disease. GPR40 is a potential therapeutic target for energy metabolic disorders. GPR40 is a potential therapeutic target for energy metabolic disorders. SZZ15-11 is a newly synthesized GPR40 agonist. In this study, we estimate the potency of SZZ15-11 in fatty liver treatment. Methods: In vivo, diet-induced obese (DIO) mice received SZZ15-11 (50 mg/kg) and TAK875 (50 mg/kg) for 6 weeks. Blood glucose and lipid, hepatocyte lipid and liver morphology were analysed. In vitro, HepG2 cells and GPR40-knockdown HepG2 cells induced with 0.3 mM oleic acid were treated with SZZ15-11. Triglyceride and total cholesterol of cells were measured. At the same time, the AMPK pathway regulating triglycerides and cholesterol esters synthesis was investigated via western blot and quantitative polymerase chain reaction in both liver tissue and HepG2 cells. Results: SZZ15-11 was found to not only attenuate hyperglycaemia and hyperlipidaemia but also ameliorate fatty liver disease in DIO mice. At the same time, SZZ15-11 decreased triglyceride and total cholesterol content in HepG2 cells. Whether examined in the liver of DIO mice or in HepG2 cells, SZZ15-11 upregulated AMPK alpha phosphorylation and then downregulated the expression of the cholesterogenic key enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase and inhibited acetyl-CoA carboxylase activity. Furthermore, SZZ15-11 promotes AMPK activity via [cAMP]i accumulation. Conclusion: This study confirmed that SZZ15-11, a novel GPR40 agonist, improves hyperlipidaemia and fatty liver, partially via Gs signalling and the AMPK pathway in hepatocytes.