ABSTRACT
ObjectiveTo investigate the therapeutic effect of Baihe Wuyaotang （BWT） on non-alcoholic fatty liver disease （NAFLD） and elucidate its underlying mechanism. MethodC57BL/6J mice were randomly assigned to six groups： normal control， model， positive drug （pioglitazone hydrochloride 1.95×10-3 g·kg-1）， and low-， medium-， and high-dose BWT （1.3，2.5 and 5.1 g·kg-1）. Following a 12-week high-fat diet （HFD） inducement， the mice underwent six weeks of therapeutic intervention with twice-daily drug administration. Body weight was monitored weekly throughout the treatment period. At the fifth week， glucose tolerance （GTT） and insulin tolerance （ITT） tests were conducted. Subsequently， the mice were euthanized for the collection of liver tissue and serum， and the subcutaneous adipose tissue （iWAT） and epididymal adipose tissue （eWAT） were weighed. Serum levels of total triglycerides （TG） and liver function indicators，such as alanine aminotransferase （ALT） and aspartate aminotransferase （AST）， were determined. Histological examinations， including oil red O staining， hematoxylin-eosin （HE） staining， Masson staining， and transmission electron microscopy， were performed to evaluate hepatic lipid deposition， pathological morphology， and ultrastructural changes， respectively. Meanwhile， Western blot and real-time quantitative polymerase chain reaction （Real-time PCR） were employed to analyze alterations， at both gene and protein levels， the insulin signaling pathway molecules， including insulin receptor substrate 1/2/protein kinase B/forkhead box gene O1 （IRS1/2/Akt/FoxO1）， glycogen synthesis enzymes phosphoenolpyruvate carboxy kinase （Pepck） and glucose-6-phosphatase （G6Pase）， lipid metabolism-related genes stearoyl-coA desaturase-1 （SCD-1） and carnitine palmitoyltransferase-1 （CPT-1）， fibrosis-associated molecules α-smooth muscle actin （α-SMA）， type Ⅰ collagen （CollagenⅠ）， and the fibrosis canonical signaling pathway transforming growth factor-β1/drosophila mothers against decapentaplegic protein2/3（TGF-β1/p-Smad/Smad2/3）， inflammatory factors such as interleukin（IL）-6， IL-8， IL-11， and IL-1β， autophagy markers LC3B Ⅱ/Ⅰ and p62/SQSTM1， and the expression of mammalian target of rapamycin （mTOR）. ResultCompared with the model group， BWT reduced the body weight and liver weight of NAFLD mice（P<0.05， P<0.01）， inhibited liver lipid accumulation， and reduced the weight of white fat： it reduced the weight of eWAT and iWAT（P<0.05， P<0.01） as well as the serum TG content（P<0.05， P<0.01）. BWT improved the liver function as reflected by the reduced ALT and AST content（P<0.05， P<0.01）. It improved liver insulin resistance by upregulating IRS2， p-Akt/Akt， p-FoxO1/FoxO1 expressions（P<0.05）. Besides， it improved glucose and lipid metabolism disorders： it reduced fasting blood glucose and postprandial blood glucose（P<0.05， P<0.01）， improved GTT and ITT（P<0.05， P<0.01）， reduced the expression of Pepck， G6Pase， and SCD-1（P<0.01）， and increased the expression of CPT-1（P<0.01）. The expressions of α-SMA， Collagen1， and TGF-β1 proteins were down-regulated（P<0.05， P<0.01）， while the expression of p-Smad/Smad2/3 was downregulated（P<0.05）， suggesting BWT reduced liver fibrosis. BWT inhibited inflammation-related factors as it reduced the gene expression of IL-6， IL-8， IL-11 and IL-1β（P<0.01） and it enhanced autophagy by upregulating LC3B Ⅱ/Ⅰ expression（P<0.05）while downregulating the expression of p62/SQSTM1 and mTOR（P<0.05）. ConclusionBWT ameliorates NAFLD by multifaceted improvements， including improving IR and glucose and lipid metabolism， anti-inflammation， anti-fibrosis， and enhancing autophagy. In particular， BWT may enhance liver autophagy by inhibiting the mTOR-mediated signaling pathway.
