Regrowth of the rat biliary tree after 70% partial hepatectomy is coupled to increased secretin-induced ductal secretion

Background & Aims: After partial hepatectomy, liver regeneration occurs with the return of hepatocyte mass to normal, Limited data exist regarding the renewal of the biliary tree after partial hepatectomy, This study tested the hypothesis that, after partial hepatectomy, the biliary tree regenerates by proliferation of the remaining cholangiocytes, leading to an increase in secretin-induced ductal bile secretion, Methods: After 70% partial hepatectomy, cholangiocyte proliferation was assessed in situ by morphometric analysis and in vitro by measurement of H-3-thymidine incorporation. Ductal secretion was estimated by measurement of secretin receptor gene expression and adenosine 3',5'-cyclic monophosphate (cAMP) levels in vitro and by the effect of secretin on ductal bile secretion in vivo, Results: DNA synthesis was undetectable in control cholangiocytes, increased and peaked at day 3 after partial hepatectomy, and returned to normal by day 28, Morphometric analysis showed regrowth of the biliary tree beginning at day 1 with restoration by day 10. The expression of secretin receptor gene and secretin-induced cAMP levels and secretin-induced bicarbonate-rich choleresis increased during the period of bile duct renewal. Conclusions: After partial hepatectomy, the increase in secretin-induced ductal bile secretion observed during bile duct renewal results from proliferation of remaining cholangiocytes.