Minimal role of hepatic transporters in the hepatoprotection against LCA-induced intrahepatic cholestasis.

Abstract

The multidrug resistance-associated proteins (Mrps) are a family of adenosine triphosphate-dependent transporters that facilitate the movement of various compounds, including bile acids, out of hepatocytes. The current study was conducted to determine whether induction of these transporters alters bile acid disposition as a means of hepatoprotection during bile acid-induced cholestasis. Lithocholic acid (LCA) was used to induce intrahepatic cholestasis. C57BL/6 mice were pretreated with corn oil (CO) or known transporter inducers, phenobarbital (PB), oltipraz (OPZ), or TCPOBOP (TC) for 3 days prior to cotreatment with LCA and inducer for 4 days. Histopathology revealed that PB and TC pretreatments provide a protective effect from LCA-induced toxicity, whereas OPZ pretreatment did not. Both PB/LCA and TC/LCA cotreatment groups also had significantly lower alanine aminotransferase values than the LCA-only group. In TC/LCA cotreated mice compared with LCA only, messenger RNA (mRNA) expression of uptake transporters Ntcp and Oatp4 was significantly increased, as were sinusoidal efflux transporters Mrp3 and Mrp4. Although in PB/LCA cotreated mice, the only significant change compared with LCA-only treatment was an increase in uptake transporter Oatp4. Oatp1 was reduced in all groups compared with CO controls. No significant changes in mRNA expression were observed in Oatp2, Bsep, Mrp2, Bcrp, Mrp1, Mrp5, or Mrp6. Mrp4 protein expression was induced in the OPZ/LCA and TC/LCA cotreated groups, whereas Mrp3 protein levels remained unchanged between groups. Protein expression of Mrp1 and Mrp5 was increased in the unprotected LCA-only and OPZ/LCA mice. Thus, transporter expression did not correlate with histologic hepatoprotection, however, there was a correlation between hepatoprotection and significantly reduced total liver bile acids in the PB/LCA and TC/LCA cotreated mice compared with LCA only. In conclusion, changes in transporter expression did not correlate with hepatoprotection, and therefore, transport may not play a critical role in the observed hepatoprotection from LCA-induced cholestasis in the C57BL/6 mouse.

• Authors: Lisa D Beilke, David G Besselsen, Quiqiong Cheng, Supriya Kulkarni, Angela L Slitt, Nathan J Cherrington
• Journal: Toxicological sciences : an official journal of the Society of Toxicology (Toxicol Sci) Vol. 102 Issue 1 Pg. 196-204 (Mar 2008) ISSN: 1096-6080 [Print] United States
• PMID: 18032408 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• ATP-Binding Cassette Transporters
• Bile Acids and Salts
• Membrane Transport Proteins
• Multidrug Resistance-Associated Proteins
• Organic Anion Transporters
• Organic Anion Transporters, Sodium-Dependent
• Protective Agents
• Pyrazines
• Pyridines
• RNA, Messenger
• Symporters
• Thiones
• Thiophenes
• sodium-bile acid cotransporter
• Lithocholic Acid
• oltipraz
• 1,4-bis(2-(3,5-dichloropyridyloxy))benzene
• Phenobarbital

Topics

• ATP-Binding Cassette Transporters (metabolism)
• Animals
• Bile Acids and Salts (metabolism)
• Cholestasis, Intrahepatic (chemically induced, genetics, metabolism, pathology, prevention & control)
• Cytoprotection
• Disease Models, Animal
• Lithocholic Acid
• Liver (drug effects, enzymology, metabolism, pathology)
• Male
• Membrane Transport Proteins (biosynthesis, genetics, metabolism)
• Mice
• Mice, Inbred C57BL
• Multidrug Resistance-Associated Proteins (metabolism)
• Organic Anion Transporters (metabolism)
• Organic Anion Transporters, Sodium-Dependent (metabolism)
• Phenobarbital (pharmacology, therapeutic use)
• Protective Agents (pharmacology, therapeutic use)
• Pyrazines (pharmacology, therapeutic use)
• Pyridines (pharmacology, therapeutic use)
• RNA, Messenger (biosynthesis)
• Symporters (metabolism)
• Thiones
• Thiophenes
• Time Factors
• Up-Regulation