To investigate the therapeutic mechanism of compound Yindan decoction (CYD) in a rat model of acute intrahepatic cholestatic (AIC).A total of 108 adult male rats were randomly divided into control (n = 18) and AIC groups (n = 90). AIC was induced in rats using alpha-naphthylisothiocyanate (ANIT) (75 mg/kg, 10 mL/kg in corn oil, p. o. ). Then, 90 AIC rats were randomly divided into five groups: a control group (n = 18), a CYD high dose group (n = 18), a CYD middle dose group (n = 18), a CYD low dose group (n = 18), and a ursodeoxycholic acid (UDCA) group (n = 18). According to sampling time, each group was subdivided into three subgroups: 24 h (n = 6), 48 h (n = 6), and 72 h groups (n = 6). The CYD-high, -middle and -low groups were orally administered 24.48, 12.24, and 6.12 g·kg－1·d－1 modified CYD, respectively, while the model group was given 20 mL/kg of body weight of distilled water once a day. The UDCA group was given 67. 5 mg·kg － 1·d － 1 UDCA once a day. Radioimmunity assay was used to detect the activity of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT) and the levels of total bilirubin (TBil) and indirect biliruin (DBil) in rats. Reverse transcription quantitative polymerase chain reaction (qRT-PCR), Western blot analysis, and immunohistochemistry were used to detect multidrug resistance-associated protein 2 (MRP2) expression. In vitro, HepG2 hepatocellular carcinoma cells were treated with CYD medicated serum at a concentration of 15 mol/L. MRP2 and retinoid X receptor alpha (RXRα) expression was analyzed by qRT-PCR and Western blotting.Serum levels of ALT, AST, GGT, ALP, TBil, and DBil were significantly reduced in the CYD and positive drug groups compared with the control group (P < 0. 05 and P < 0.01, respectively). Pathological changes in rat liver tissues at 72 h in the CYD-high and -medium dose groups and positive drug group were not significant compared with the control group. CYD and UDCA treatment ameliorated ANIT-induced biliary epithelial cell proliferation. Neutrophil infiltration was rare and little focal necrosis was observed in lobules in the CYD-high and -medium dose groups and UDCA group at 72 h. Compared with the control group, the expression of MRP2 mRNA and MRP2 protein in the liver tissue of the CYD groups was significantly increased (P < 0. 05 and P < 0. 01, respectively). MRP2 expression and RXRα nuclear receptor mRNA and protein levels in the CYD groups were significantly increased compared with the control and UDCA groups (P < 0. 01).CYD can alleviate cholestasis in ANIT-induced AIC rats, and the mechanism underlying this action might involve increases in ALT, AST, GGT, ALP, TBil, and DBil and upregulation of MRP2 and RXRα mRNA and protein levels.
