Effect of geniposidic acid on hepato-enteric circulation in cholestasis rats through Sirt1-FXR signaling pathway / 中国中药杂志

ABSTRACT

To investigate the effects of geniposidic acid( GPA) on hepato-enteric circulation in cholestasis rats,and to explore the mechanism based on the sirtuin 1( Sirt1)-farnesol X receptor( FXR) pathway,sixty SD rats were randomly divided into 6 groupsblank control group,ANIT model group,ursodeoxycholic acid group( 100 mg·kg~(-1)·d-1 UDCA),and GPA high,medium and low( 100,50 and 25 mg·kg~(-1)·d-1) dosage groups,10 rats in each group. Corresponding drugs were intragastrically( ig) administered for10 days. After administration on day 8,all rats except blank rats were administered with 65 mg·kg~(-1)α-naphthalene isothiocyanate( ANIT) once. After the last administration,the serum levels of alanine aminotransferase( ALT),glutamine oxalacetate aminotransferase( AST),gamma-glutamyltransferase( γ-GGT),alkaline phosphatase( ALP),total bilirubin( TB) and total bile acid( TBA)were measured,and the mRNA transcription levels of Sirt1,FXR,multidrug resistant associated protein 2( MRP2),bile salt export pump( BSEP),sodium taurocholate contractible polypeptide( NTCP) in liver and apical sodium bile acid transporter( ASBT),ileum bile acid binding protein( IBABP) in ileum were detected by reverse transcription-polymerase chain reaction( RT-PCR). The protein expression levels of Sirt1,FXR and NTCP were detected by Western blot; the expression of MRP2,BSEP in liver and ASBT,IBABP in ileum were determined by immunofluorescence three staining. Primary rat hepatocytes were cultured in vitro to investigate the inhibitory effect of GPA on a potent and selective Sirt1 inhibitor( EX 527),and the mRNA and protein expression levels of Sirt1 and FXR were detected by RT-PCR and Western blot. GPA significantly decreased the levels of ALT,AST,γ-GGT,ALP,TB,TBA in serum( P<0.01) and improved the pathological damage of liver tissues in ANIT-induced cholestasis rats; significantly increased the mRNA and protein expression levels of Sirt1,FXR,MRP2,BSEP,NTCP in liver and ASBT,IBABP in ileum( P< 0.01). In vitro primary hepatocytes experiment indicated that the gene and protein expression levels of FXR and Sirt1 were noticeably improved by GPA in primary hepatocytes inhibited by EX-527( P<0.01). It was found that the improvement of GPA was in a dose-dependent manner. GPA could improve bile acid hepatointestinal circulation and play a liver protection and cholagogu role in cholestasis rats induced by ANIT.The mechanism may be that GPA activated FXR by regulating Sirt1,a key regulator of oxidative stress injury,and then the activated FXR could regulate protein of bile acid hepato-enteric circulation.