Dioscin protects against ANIT-induced cholestasis via regulating Oatps, Mrp2 and Bsep expression in rats

Alpha-naphthylisothiocyanate (ANIT) is a toxicant that is widely used in rodents to model human intrahepatic cholestasis. The aim of the study is to investigate whether effects of dioscin on ANIT-induced cholestasis are related to changes in expression of hepatic transporters in rats. Effects of dioscin on cholestasis were examined by histology and biochemical marker levels. The functional changes of hepatic transporters were determined by in vitro, in situ and in vivo. qRT-PCR and western blot were used to assess the expression of hepatic transporters in cholestatic rats. Dioscin administration could ameliorate cholestasis, as evidenced by reduced biochemical markers as well as improved liver pathology. The uptakes of organic anion transporting polypeptide (Oatp) substrates were altered in liver uptake index in vivo, perfused rat liver in situ and isolated rat hepatocytes in vitro in cholestasis rats. qRT-PCR and western blot analysis indicated co-treatment of ANIT with dioscin prevented the adaptive down-regulation of Oatp1a1, 1b2, and prompted the up-regulation of Oatp1a4, multidrug resistance-associated protein (Mrp) 2 and bile salt export pump (Bsep). In addition, concerted effects on Mrp2 and Bsep occurred through up-regulation of small heterodimer partner by activating farnesoid X receptor. Dioscin might prevent impairment of hepatic function by restoring hepatic transporter expression.

Analyzing the hepatoprotective effect of the Swertia cincta Burkillextract against ANIT-induced cholestasis in rats by modulating the expression of transporters and metabolic enzymes

ETHNOPHARMACOLOGICAL RELEVANCE

Swertia cincta Burkill was traditionally used for treating jaundice and various types of chronic and acute hepatitis in Yunnan and Tibet in China for hundreds of years. This study aims to investigate the protective effect of S. cincta Burkill (ESC) extract on alpha-naphthylisothiocyanate (ANIT)-induced hepatotoxicity and cholestasis in rats.

MATERIALS AND METHODS

Crude extracts were prepared using 90% ethanol and by vacuum drying. We utilized an ultra-high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UHPLC/Q-TOF-MS) system to conduct a phytochemical analysis of the active components of ESC. Liver function was evaluated by measuring the serum levels of enzymes and components and by analyzing the liver histology. We also measured the expression of bile metabolism-related transporters and metabolic enzymes at both protein and mRNA levels to elucidate the underlying mechanisms.

RESULTS

ESC analysis using an UHPLC/Q-TOF-MS revealed eight compounds. Oral administration of ESC to ANIT-treated rats can significantly reduce the increases in serum levels of ALT, AST, ALP, TBIL, and TBA. It can also improve liver pathology and bile flow. Western blot and qRT-PCR analyses showed that ESC upregulated the protein and mRNA expression of Fxr, Ntcp, Bsep, Cyp7a1, Mrp2, and Mdr2.

CONCLUSION

ESC could alleviate liver injury by reducing enzyme activities of serums, improving liver pathology and bile flow. The protective mechanism was associated with regulation of the expression of hepatic transporters and metabolic enzymes.

Allopurinol Protects Against Cholestatic Liver Injury in Mice Not Through Depletion of Uric Acid

Cholestasis is one of the most severe manifestations of liver injury and has limited therapeutic options. Allopurinol (AP), an inhibitor of uric acid (UA) synthesis, was reported to prevent liver damage in several liver diseases. However, whether AP protects against intrahepatic cholestatic liver injury and what is the role of UA in the pathogenesis of cholestasis remain unknown. In this study, we reported that AP attenuated liver injury in a mouse model of intrahepatic cholestasis induced by alpha-naphthylisothiocyanate (ANIT). AP showed no significant effect on glutathione depletion, inflammation, or bile acid metabolism in livers of ANIT-treated mice. Instead, AP significantly improved fatty acid β-oxidation in livers of ANIT-treated mice, which was associated with activation of PPARα. The protective effect of AP on cholestatic liver injury was not attributable to the depletion of UA, because both exogenous and endogenous UA prevented liver injury in ANIT-treated mice via inhibition of NF-kB-mediated inflammation. In conclusion, the present study provides a new perspective for the therapeutic use of AP and the role of UA in cholestatic liver injury.