Ginsenoside Ro Ameliorates High-Fat Diet-Induced Obesity and Insulin Resistance in Mice via Activation of the G Protein-Coupled Bile Acid Receptor 5 Pathway

Obesity, a well known risk factor in multiple metabolic diseases, is dramatically increasing worldwide. Ginsenosides extracted from ginseng have been reported against obesity and the associated metabolic disorders. As a subtype of ginsenoside, ginsenoside Ro is a critical constituent of ginseng. However, its specific effects on obesity remain unknown. G protein-coupled bile acid receptor 5 (TGR5) (also known as GPBAR1) is a bile acid membrane receptor, widely expressed in human tissues contributing to various metabolic processes to confer the regulations of glucose and lipid homeostasis. TGR5 has displayed potential as a therapeutic target for the treatment of metabolic disorders. Here, we explore the antiobesity effect of ginsenoside Ro with TGR5 activation screened by a library of natural products. Our results showed that the ginsenoside Ro (90mg/ kg) treatment ameliorated body weight and lipid accumulation in multiple metabolic organs of high-fat diet-induced obese (DIO) mice without affecting food intake and improved oral glucose tolerance tests, intraperitoneal insulin tolerance tests, and fasting serum glucose. We also found that triglyceride and total cholesterol in serum and liver were significantly decreased after ginsenoside Ro treatment. Then we used Tgr5 knockout mice to explore the role of Tgr5 in the antiobesity effect of ginsenoside Ro. Our results further demonstrated that ginsenoside Ro promoted glucagon-like peptide 1 (GLP-1) secretion and energy expenditure in wild-type DIO mice. However, the stimulation of ginsenoside Ro on GLP-1 secretion and energy expenditure were restrained in the Tgr5 knockout mice. In conclusion, our findings demonstrated that ginsenoside Ro ameliorates obesity and insulin resistance in DIO mice via activating TGR5, indicating a potential therapeutic role of ginsenoside Ro to treat obesity and its associated metabolic diseases.