Bile canalicular barrier function and expression of tight-junctional molecules in rat hepatocytes during common bile duct ligation

Abstract

Tight junctions of hepatocytes form the intercellular barrier between the blood circulation and bile flow. We focused on early stages of common bile duct ligation to observe changes in tight junctions without the irreversible changes seen after lengthy ligation. Common bile ducts of 12-week-old male rats were ligated for 6 h because, at this time point, no histological changes were observed. Serum bilirubin and bile acid levels began to increase 3 h after ligation and were restored to the control level immediately after surgical removal of the ligation. To examine the barrier of hapatocytes, horseradish peroxidase was injected via the femoral vein, and bile was collected for the first 10 min. A four-fold elevation of the secretion and concentration was observed in the bile of ligated rats compared with that of control animals. We next examined lanthanum permeability by perfusion fixation of the liver. At 6 h after ligation, both dilation of the bile canaliculi and partial loss of microvilli were commonly observed. There were dense deposits of lanthanum in almost all bile canaliculi of ligated rats. In control animals, neither dilation of the bile canaliculi nor loss of microvilli was detected, and only 44% of bile canaliculi exhibited deposits. An apparent increase of occludin mRNA expression was detected in livers after 6 h ligation, whereas the expression of claudin-1, -2, and -3 was not influenced by ligation. These results indicate that regulation of occludin gene expression is different from that of claudin-1, -2, and -3. The early phase of bile stasis employed in this study is thought to be an indispensable approach for understanding the precise regulation of tight junctions.

Disruption of function and localization of tight junctional structures and Mrp2 in sustained estradiol-17β-d-glucuronide-induced cholestasis

“…Furthermore, the canalicular protein Ca 2ϩ -Mg 2ϩ -ATPase was shown to undergo endocytic internalization and selective redistribution to the lateral membrane in chronic, experimental obstructive cholestasis (30), a model that is also accompanied by increased tight junctional permeability (32) and endocytic internalization of Mrp2 (23). Irrespective of the mechanism, endocytic internalization and selective relocalization to the lateral membrane under sustained E 2 17G cholestasis were not restricted to Mrp2, as a similar phenomenon was observed for DPPIV.…”

Bile duct epithelial tight junctions and barrier function

“…Immunofluorescence staining of cryosections of rat liver indicated a linear distribution of 7H6 around the canalicular lumen 47 . Further studies demonstrated the expression of claudin 1, 2 and 3 in rat liver 48 . In zebra fish, the expression of claudin 15-like b protein was found to be essential for bile duct morphogenesis 49 .…”

Alteration of Methotrexate Biliary and Renal Elimination during Extrahepatic and Intrahepatic Cholestasis in Rats

“…9) In such cases, changes in the pharmacokinetics of the drug could be partly predicted from the results of the detailed studies of transporter expression in the liver and kidneys and from in vitro studies in isolated cells. Nevertheless, the existence of other mechanisms involved in the pathophysiology of cholestasis such as paracellular leakage through an impaired blood-biliary barrier (tight-junction connection of hepatocytes) or decreased perfusion of organs 10) makes such predictions less accurate and raises the need for data from in vivo kinetic studies.…”