title: Effect of bile pigments on the compromised gut barrier function in a rat model of bile duct ligation.
abstract: BACKGROUND
  Studies have shown that the absence of bile in the gut lumen, either by bile duct ligation or bile diversion, induces mucosal injury. However, the mechanism remains elusive. In this study, the role of bile pigments in gut barrier function was investigated in a rat model of bile duct ligation.
  
  
  METHODS
  Male Sprague Dawley (SD) rats were used in this study. After ligation of bile duct, the animals were administrated with free bilirubin, bilirubin ditaurate, or biliverdin by intragastric gavage. 1, 2, or 3 days later, the animals were sacrificed and the damage of mucosa was assessed by histological staining as well as biochemical parameters such as changes of diamine oxidase (DAO) and D-lactate (D-Lac) in the blood. Trypsin and chymotrypsin of the gut were also measured to determine how these digestive proteases may relate to the observed effects of bile pigments.
  
  
  RESULTS
  Bile duct ligation (BDL) caused significant increases in gut trypsin and chymotrypsin along with damage of the mucosa as demonstrated by the histological findings under microscope, the reduced expression of tight junction molecules like occludin, and significant changes in DAO and D-lac in the blood. Free bilirubin but not bilirubin ditaurate or biliverdin showed significant inhibitions on trypsin and chymotrypsin as well as alleviated changes of histological and biochemical parameters related to gut barrier disruption.
  
  
  CONCLUSIONS
  Bile may protect the gut from damage through inhibiting digestive proteases like trypsin and chymotrypsin by free bilirubin.
authors.affiliation: Department of Biochemistry and Molecular Biology, Heilongjiang Provincial Science and Technology Innovation Team in Higher Education Institutes for Infection and Immunity, Harbin Medical University, Harbin, China.
authors.forename: Kangkang
authors.initials: K
authors.lastname: Zhou
authors.affiliation: Department of General Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China.
authors.forename: Mingshan
authors.initials: M
authors.lastname: Jiang
authors.affiliation: Department of Biochemistry and Molecular Biology, Heilongjiang Provincial Science and Technology Innovation Team in Higher Education Institutes for Infection and Immunity, Harbin Medical University, Harbin, China.
authors.forename: Yuanli
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Biochemistry and Molecular Biology, Heilongjiang Provincial Science and Technology Innovation Team in Higher Education Institutes for Infection and Immunity, Harbin Medical University, Harbin, China.
authors.forename: Yilin
authors.initials: Y
authors.lastname: Qu
authors.affiliation: Department of Biochemistry and Molecular Biology, Heilongjiang Provincial Science and Technology Innovation Team in Higher Education Institutes for Infection and Immunity, Harbin Medical University, Harbin, China.
authors.forename: Guojing
authors.initials: G
authors.lastname: Shi
authors.affiliation: Department of Biochemistry and Molecular Biology, Heilongjiang Provincial Science and Technology Innovation Team in Higher Education Institutes for Infection and Immunity, Harbin Medical University, Harbin, China.
authors.forename: Xinguang
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Surgery, Rutgers-New Jersey Medical School, Newark, New Jersey, United States of America.
authors.forename: Xiaofa
authors.initials: X
authors.lastname: Qin
authors.affiliation: Department of Biochemistry and Molecular Biology, Heilongjiang Provincial Science and Technology Innovation Team in Higher Education Institutes for Infection and Immunity, Harbin Medical University, Harbin, China.
authors.forename: Xiuhong
authors.initials: X
authors.lastname: Wang
mesh_terms: D000818:Animals; D001652:Bile Ducts / Q000601:surgery*; D001654:Bile Pigments / Q000378:metabolism*; D001663:Bilirubin / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002918:Chymotrypsin / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology; D008026:Ligation; D008297:Male; D023421:Models, Animal; D010539:Permeability; D051381:Rats; D014357:Trypsin / Q000378:metabolism
chemical_list: D001654:Bile Pigments; D015415:Biomarkers; D002918:Chymotrypsin; D014357:Trypsin; D001663:Bilirubin