Radix Astragali Improves Dysregulated Triglyceride Metabolism and Attenuates Macrophage Infiltration in Adipose Tissue in High-Fat Diet-Induced Obese Male Rats through Activating mTORC1-PPARγ Signaling Pathway

Increased levels of free fatty acids (FFAs) and hypertriglyceridemia are important risk factors for cardiovascular disease. The effective fraction isolated from radix astragali (RA) has been reported to alleviate hypertriglyceridemia. The mechanism of this triglyceride-lowering effect of RA is unclear. Here, we tested whether activation of the mTORC1-PPAR γ signaling pathway is related to the triglyceride-lowering effect of RA. High-fat diet-induced obese (DIO) rats were fed a high-fat diet (40% calories from fat) for 9-10 weeks, and 4 g/kg/d RA was administered by gavage. RA treatment resulted in decreased fasting triglyceride levels, FFA concentrations, and adipocyte size. RA treated rats showed improved triglyceride clearance and fatty acid handling after olive oil overload. RA administration could also decrease macrophage infiltration and expression of MCP-1 and TNF α , but it may also increase the expression of PPAR γ in epididymal adipose tissue from RA treated rats. Consistently, expressions of PPAR γ and phospho-p70S6K were increased in differentiated 3T3-L1 adipocytes treated with RA. Moreover, RA couldnot upregulate the expression of PPAR γ at the presence of rapamycin. In conclusion, the mTORC1-PPAR γ signaling pathway is a potential mechanism through which RA exerts beneficial effects on the disturbance of triglyceride metabolism and dysfunction of adipose tissue in DIO rats.