title: Pregnane X receptor activation protects rat hepatocytes against deoxycholic acid-induced apoptosis.
abstract: OBJECTIVE
  Bile acids damage the liver, essentially by inducing hepatocyte apoptosis. Clinical studies have shown that several activators of the pregnane X receptor (PXR) may induce the remission of cholestasis. However, the molecular mechanisms involved in this beneficial effect remain unclear. We analysed the effect of an activator of PXR, clotrimazole (CLO), on the apoptosis induced by bile acids in primary cultures of rat hepatocytes.
  
  
  METHODS
  Rat hepatocytes were isolated by collagenase perfusion of the liver. Then, cells were pretreated with CLO for 24 h, after which they were exposed to deoxycholic and glycochenodeoxycholic acids (DCA, GCDCA). Apoptosis and necrosis were monitored morphologically and biochemically using cytotoxicity assays, phase-contrast microscopy, Annexin V/propidium iodide staining and evaluations of lactate dehydrogenase release. The activation of caspases and the proteolysis of their substrates were analysed by enzyme assays and Western blot. The signal transductions involved in the protective effect of the PXR activation were analysed by assessing the phosphorylation status of kinases belonging to the ERK, Akt and p38 pathways and by analysing pro- and anti-apoptotic proteins.
  
  
  RESULTS
  CLO protected rat hepatocytes against DCA- and GCDCA-induced apoptosis, preventing morphological aspects of this process (membrane blebbing, nuclear and chromatin condensation and DNA breakdown). This effect was attributable, at least partly, to caspases inhibition, Bcl-xL induction, the activation of ERK and Akt signalling and p38 inhibition.
  
  
  CONCLUSIONS
  This study provides the description of the cytoprotective effect of PXR activation against bile acid-induced apoptosis and highlights molecular pathways that could be targeted in the treatment of cholestasis.
authors.affiliation: Laboratoire de Toxicologie Cellulaire, Moléculaire et Génomique, INRA, Sophia Antipolis, France. zucchini@sophia.inra.fr
authors.forename: Nathalie
authors.initials: N
authors.lastname: Zucchini-Pascal
authors.forename: Georges
authors.initials: G
authors.lastname: de Sousa
authors.forename: Jérôme
authors.initials: J
authors.lastname: Pizzol
authors.forename: Roger
authors.initials: R
authors.lastname: Rahmani
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002756:Cholagogues and Choleretics / Q000494:pharmacology*; D003022:Clotrimazole / Q000494:pharmacology*; D019610:Cytoprotection / Q000187:drug effects; D003840:Deoxycholic Acid / Q000494:pharmacology*; D004195:Disease Models, Animal; D004347:Drug Interactions; D005999:Glycochenodeoxycholic Acid / Q000494:pharmacology; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008297:Male; D000077297:Pregnane X Receptor; D051381:Rats; D017207:Rats, Sprague-Dawley; D011987:Receptors, Steroid / Q000378:metabolism*
chemical_list: D002756:Cholagogues and Choleretics; D000077297:Pregnane X Receptor; D011987:Receptors, Steroid; D003840:Deoxycholic Acid; D005999:Glycochenodeoxycholic Acid; D003022:Clotrimazole