TUDCA prevents cholestasis and canalicular damage induced by ischemia-reperfusion injury in the rat, modulating PKCα-ezrin pathway

Cholestasis, induced by liver ischemia-reperfusion injury (IRI), is characterized by dilatation of bile canaliculi and loss of microvilli. Tauroursodeoxycholic acid (TUDCA) is an anti-cholestatic agent, modulating protein kinase C (PKC) alpha pathway. PKC reduces ischemic damage in several organs, its isoform alpha modulates ezrin, a key protein in the maintenance of cell lamellipoidal extensions. We evaluated the effects of TUDCA on cholestasis, canalicular changes and PKC alpha-ezrin expression in a rat model of liver IRI. Livers flushed and stored with Belzer solution or Belzer + 10 mM TUDCA (4 degrees C for 6 h) were reperfused (37 degrees C with O-2) with Krebs-Ringer bicarbonate + 2.5 mu mol/min of Taurocholate or TUDCA. Bile was harvested for bile flow assessment. Liver tissue was employed for Electron Microscopy (EM) and for PKC alpha and ezrin immunoblot and immunofluorescence. The same experiments were conducted with the PKC alpha inhibitor Go-6976. TUDCA-treated livers showed increased bile flow (0.25 +/- 0.17 vs. 0.042 +/- 0.02 mu l/min/g liver, P < 0.05) and better preservation of microvilli and bile canalicular area at EM. These effects were associated with increased PKC alpha and ezrin expression (P = 0.03 and P = 0.04 vs. control respectively), as also confirmed by immunofluorescence data. PKC alpha inhibition abolished these TUDCA effects. TUDCA administration during IRI reduces cholestasis and canalicular damage in the liver modulating PKC alpha-ezrin pathway.