scholarly journals Regulation of cholesterol and bile acid homoeostasis in bile-obstructed rats

1991 ◽  
Vol 280 (2) ◽  
pp. 373-377 ◽  
Author(s):  
S Dueland ◽  
J Reichen ◽  
G T Everson ◽  
R A Davis
Keyword(s):  
Bile Acid ◽  
Bile Duct ◽  
Liver Function ◽  
Urinary Excretion ◽  
Bile Acids ◽  
Bile Duct Ligation ◽  
Microsomal Cytochrome ◽  
Duct Ligation ◽  
Cytochrome P 450

We examined how total blockage of biliary excretion, the major pathway through which cholesterol and bile acids are removed from the body, affects liver function, cholesterol and bile acid metabolism and homoeostasis. After 4 weeks of bile-duct ligation, rats showed impaired liver function, as documented by elevations in serum bilirubin and alkaline phosphatase activity. Moreover, bile-duct ligation decreased by about 30% both the amount of microsomal cytochrome P-450 in the liver and the elimination of aminopyrine in vivo, a reliable index in vivo of microsomal mixed-function oxidase activity. Cholesterol and bile acid contents in livers of bile-duct-ligated rats were doubled compared with sham-operated controls. Despite the increase in the contents of cholesterol and bile acids in liver, activities of the respective rate-limiting enzymes, 3-hydroxy-3-methylglutaryl-CoA reductase and cholesterol 7 alpha-hydroxylase, were doubled. Serum concentrations of bile acids and free cholesterol increased 25- and 4-fold respectively. The large increase in serum bile acids was associated with a 380-fold increase in the urinary excretion of bile acids. Although there is a general decrease in cytochrome P-450 content and drug metabolism involving cytochrome P-450-containing hydroxylases, the activity of cholesterol 7 alpha-hydroxylase, also a cytochrome P-450-containing enzyme, is actually increased. These data show that complete obstruction of the bile duct results in the selective impairment of microsomal cytochrome P-450. Increased activity of 7 alpha-hydroxylase, bile acid synthesis and urinary excretion provides an alternative excretory pathway that helps to maintain cholesterol homoeostasis when the biliary excretory pathway is eliminated.

scholarly journals Neither intestinal sequestration of bile acids nor common bile duct ligation modulate the expression and function of the rat ileal bile acid transporter

Hepatology ◽  
1998 ◽  
Vol 28 (4) ◽  
pp. 1081-1087 ◽  
Author(s):  
Marco Arrese ◽  
Michael Trauner ◽  
Robert J. Sacchiero ◽  
Michael W. Crossman ◽  
Benjamin L. Shneider
Keyword(s):  
Bile Acid ◽  
Bile Duct ◽  
Common Bile Duct ◽  
Bile Acids ◽  
Bile Duct Ligation ◽  
Common Bile Duct Ligation ◽  
Duct Ligation ◽  
Bile Acid Transporter ◽  
Acid Transporter ◽  
And Function

scholarly journals Vitamin A Supplementation Alleviates Extrahepatic Cholestasis Liver Injury through Nrf2 Activation

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Guiyang Wang ◽  
Peng Xiu ◽  
Fu Li ◽  
Cheng Xin ◽  
Kewei Li
Keyword(s):  
Bile Duct ◽  
Liver Injury ◽  
Liver Function ◽  
Vitamin A ◽  
Western Blotting ◽  
Bile Duct Ligation ◽  
Retinyl Palmitate ◽  
Binding Activity ◽  
Extrahepatic Cholestasis ◽  
Duct Ligation

Aim. To investigate the role of vitamin A in liver damage induced by bile duct ligation (BDL) in rats.Methods. Thirty male Wistar rats were randomly divided into three groups: SHAM group, BDL group, and BDL + VitA group . The concentrations of retinol and retinyl palmitate in the liver were analyzed using HPLC, and liver function was evaluated by the level of TBIL, ALT, AST, and ALP in serum. Hepatic oxidative status was estimated by measuring T-SOD, CAT, GSH, MDA, and AOPP. Nrf2 expression was assessed using immunohistochemistry and western blotting, and EMSA was performed to determine Nrf2 DNA-binding activity. The expression of the downstream factors such as Ho1 and Nqo1 was also examined using immunohistochemistry and western blotting assays.Results. Vitamin A treatment restored levels of retinoids in liver, improved liver function, alleviated oxidative stress, and facilitated the translocation of Nrf2 to the nucleus in the experimental obstructive jaundice. Vitamin A was also found to increase the expression of Nrf2 downstream proteins such as Ho1 and Nqo1.Conclusion. Vitamin A was here found to ameliorate cholestatic liver injury. This effect may be related to the activation of Nrf2/ARE pathway in bile duct ligation rats.

Vitamin D inhibits development of liver fibrosis in an animal model but cannot ameliorate established cirrhosis

2015 ◽  
Vol 308 (2) ◽  
pp. G112-G120 ◽  
Author(s):  
Shirley Abramovitch ◽  
Efrat Sharvit ◽  
Yosef Weisman ◽  
Amir Bentov ◽  
Eli Brazowski ◽  
...  
Keyword(s):  
Vitamin D ◽  
Growth Factor ◽  
Bile Duct ◽  
Liver Fibrosis ◽  
Bile Duct Ligation ◽  
Active Form ◽  
Preventive Treatment ◽  
Antifibrotic Effect ◽  
Duct Ligation

1,25(OH)2D3, the active form of vitamin D, has an antiproliferative and antifibrotic effect on hepatic stellate cells. Our aim was to investigate the potential of 1,25(OH)2D3 to inhibit the development of liver fibrosis and to ameliorate established fibrosis in vivo. The antifibrotic effect of 1,25(OH)2D3 was investigated in a thioacetamide (TAA) model (as a preventive treatment and as a remedial treatment) and in a bile duct ligation model. In the preventive model, rats received simultaneously intraperitoneum injection of TAA and/or 1,25(OH)2D3 for 10 wk. In the remedial model, rats were treated with TAA for 10 wk and then received 1,25(OH)2D3 or saline for 8 wk. Fibrotic score was determined by Masson staining. Collagen I, α-smooth muscle actin (α-SMA), tissue inhibitor of metalloproteinase-1 (TIMP1), platelet-derived growth factor (PDGF), and transforming growth factor-β (TGF-β) expression were measured by Western blot analysis and real-time PCR. Hypercalemia was detected by chemistry measurements. Preventive treatment of 1,25(OH)2D3 significantly suppressed liver fibrosis both macroscopically and microscopically and significantly lowered the fibrotic score of the TAA + 1,25(OH)2D3 group compared with the TAA group. 1,25(OH)2D3 significantly inhibited expression of PDGF and TGF-β by ∼50% and suppressed the expression of collagen Iα1, TIMP1, and α-SMA by approximately three-, two-, and threefold, respectively. In contrast, 1,25(OH)2D3 was inefficient in amelioration of established liver fibrosis. Administration of 1,25(OH)2D3 to bile duct ligation rats led to a high mortality rate probably caused by hypercalcemia. We conclude that 1,25(OH)2D3 may be considered as a potential preventive treatment in an in vivo model but failed to ameliorate established cirrhosis.

Bile duct cells: a novel in vitro model for the study of lipid metabolism and bile acid production

1999 ◽  
Vol 276 (2) ◽  
pp. G407-G414 ◽  
Author(s):  
Monika Zoltowska ◽  
Edgard E. Delvin ◽  
Khazal Paradis ◽  
Ernest Seidman ◽  
Emile Levy
Keyword(s):  
Bile Acid ◽  
Bile Duct ◽  
Bile Acids ◽  
Cytokeratin 19 ◽  
Sterol Metabolism ◽  
Hmg Coa Reductase ◽  
Biliary Epithelium ◽  
Duct Cells ◽  
Coa Reductase

Immortalized bile duct cells (BDC), derived from transgenic mice harboring the SV40 thermosensitive immortalizing mutant gene ts458, were utilized to investigate the role of the biliary epithelium in lipid and sterol metabolism. This cell model closely resembles the in vivo situation because it expresses the specific phenotypic marker cytokeratin 19 (CK-19), exhibits the formation of bile duct-like structures, and displays well-formed microvilli projected from the apical side to central lumen. The BDC were found to incorporate [14C]oleic acid (in nmol/mg protein) into triglycerides (121 ± 6), phospholipids (PL; 59 ± 3), and cholesteryl ester (16 ± 1). The medium lipid content represented 5.90 ± 0.16% ( P < 0.005) of the total intracellular production, indicating a limited lipid export capacity. Analysis of PL composition demonstrated the synthesis of all classes of polar lipids, with phosphatidylcholine and phosphatidylethanolamine accounting for 60 ± 1 and 24 ± 1%, respectively, of the total. Differences in PL distribution were apparent between cells and media. Substantial cholesterol synthesis was observed in BDC, as determined by the incorporation of [14C]acetate suggesting the presence of hydroxymethylglutaryl-CoA (HMG-CoA) reductase, the rate-limiting enzyme in the cholesterol biosynthetic pathway. With the use of [14C]acetate and [14C]cholesterol as precursors, both tauro- and glycoconjugates of bile acids were synthesized, indicating the presence of cholesterol 7α- and 26R-hydroxylases, the key enzymes involved in bile acid formation. The transport of bile acids was not limited, as shown by their marked accumulation in the medium (>6-fold of cell content). HMG-CoA reductase (53.0 ± 6.7), cholesterol 7α-hydroxylase (15.5 ± 0.5), and acyl-CoA:cholesterol acyltransferase (ACAT; 201.7 ± 10.2) activities (in pmol ⋅ min−1 ⋅ mg protein−1) were present in the microsomal fractions. Our data show that biliary epithelial cells actively synthesize lipids and may directly contribute bile acids to the biliary fluid in vivo. This BDC line thus represents an efficient experimental tool to evaluate biliary epithelium sterol metabolism and to study biliary physiology.

Peripheral vascular neuroeffector mechanisms in experimental cholestasis

1993 ◽  
Vol 265 (3) ◽  
pp. G579-G586 ◽  
Author(s):  
G. Jacob ◽  
O. Said ◽  
J. Finberg ◽  
A. Bomzon
Keyword(s):  
Electrical Stimulation ◽  
Bile Duct ◽  
Vascular Reactivity ◽  
Bile Duct Ligation ◽  
Norepinephrine Uptake ◽  
Pithed Rats ◽  
Duct Ligation ◽  
Adrenoceptor Agonists

Jaundiced patients have systemic hypotension and are more susceptible to hemorrhagic shock than nonjaundiced individuals. We have hypothesized that the mechanism whereby these cardiovascular complications arise is linked to a disturbance of the vascular neuroeffector process in the cardiovascular system. With the use of 3-day bile duct-manipulated (sham-operated) and bile duct-ligated rats, we have evaluated alpha-adrenoceptor function and amine uptake using in vivo and in vitro techniques. Blunted pressor responsiveness to norepinephrine, electrical stimulation, and the alpha 1-adrenoceptor agonists, methoxamine and phenylephrine, was observed in the bile duct-ligated pithed rats. In contrast, normal responsiveness to BHT-933 and clonidine, the alpha 2-adrenoceptor agonists, was seen in these animals. The uptake 1 blocker, cocaine, caused potentiation of equal magnitudes of the pressor responsiveness to electrical stimulation and norepinephrine in the sham-operated and bile duct-ligated pithed rats. In aortic rings prepared from the bile duct-ligated rats, blunted in vitro vascular reactivity to norepinephrine and the same alpha 1-adrenoceptor agonists was seen. Bile duct ligation had no effect on norepinephrine uptake or its kinetics in stressed and unstressed arterial rings and portal veins. We have thus concluded that bile duct ligation induces a defect in the functional expression of cardiovascular alpha 1-adrenoceptors without any effects on the activity of alpha 2-adrenoceptors or norepinephrine uptake.

Differential alteration of cytochrome P450 isoenzymes in two experimental models of cirrhosis

2000 ◽  
Vol 78 (11) ◽  
pp. 912-919 ◽  
Author(s):  
Marie-Claude Bastien ◽  
François Leblond ◽  
Vincent Pichette ◽  
Jean-Pierre Villeneuve
Keyword(s):  
Cytochrome P450 ◽  
Carbon Tetrachloride ◽  
Bile Duct ◽  
Serum Albumin ◽  
Breath Test ◽  
Bile Duct Ligation ◽  
Biliary Cirrhosis ◽  
Breath Tests ◽  
Duct Ligation

Liver diseases are associated with a decrease in hepatic drug elimination, but there is evidence that cirrhosis does not result in uniform changes of cytochrome P450 (CYP) isoenzymes. The objective of this study was to determine the content and activity of four CYP isoenzymes in the bile duct ligation and carbon tetrachloride (CCl4)-induced models of cirrhosis. The hepatic content of CYP1A, CYP2C, CYP2E1, and CYP3A was measured by Western blot analysis. CYP activity in vivo was evaluated with breath tests using substrates specific for different isoenzymes: caffeine (CYP1A2), aminopyrine (CYP2C11), nitrosodimethylamine (CYP2E1), and erythromycin (CYP3A). Bile duct ligation resulted in biliary cirrhosis; CYP1A, CYP2C and CYP3A content was decreased and the caffeine, aminopyrine, and erythromycin breath tests were reduced whereas CYP2E1 content and the nitrosodimethylamine breath test were unchanged compared with controls. CCl4 treatment resulted in cirrhosis of varying severity as assessed from the decrease in liver weight and serum albumin. In rats with mild cirrhosis, CYP content was comparable with controls except for a decrease in CYP2C. The activity of CYPs was also unchanged except for an increase in CYP2E1 activity. In rats with more severe cirrhosis, the content of all four CYP isoenzymes and the caffeine, aminopyrine, and erythromycin breath tests were reduced whereas the nitrosodimethylamine breath test was unchanged. In both models of cirrhosis, there was a significant correlation between the breath tests results and the severity of cirrhosis as assessed from serum albumin levels. These results indicate that content and the catalytic activity of individual CYP enzymes are differentially altered by cirrhosis in the rat and also suggest that drug probes could be useful to assess hepatic functional reserve.Key words: breath test, cirrhosis, cytochrome P450, bile duct ligation, carbon tetrachloride.

scholarly journals Effect of bile duct ligation on bile acid composition in mouse serum and liver

2011 ◽  
Vol 32 (1) ◽  
pp. 58-69 ◽  
Author(s):  
Youcai Zhang ◽  
Ji-Young Hong ◽  
Cheryl E. Rockwell ◽  
Bryan L. Copple ◽  
Hartmut Jaeschke ◽  
...  
Keyword(s):  
Bile Acid ◽  
Bile Duct ◽  
Acid Composition ◽  
Bile Duct Ligation ◽  
Mouse Serum ◽  
Duct Ligation
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