Analyses on lipid-rich organelles of the rat liver after bile duct ligation

A fraction of lipid-rich organelles of rat livers was analyzed to study the effect of bile duct ligation on lipid metabolism. The lipid fraction of the control rats consisted mainly of Golgi-derived dense bodies. Three days after the ligation, myelin-like figures and increased phospholipids and cholesterol were characteristic of the fraction. Two weeks ligation resulted in proliferation of lysosomal electron dense bodies. As their volume density expanded, phospholipids and cholesterol increased. Electrophoresis indicated a reduced rate of VLDL assembly after ligation. The Golgi-dominant phase is converted to the lysosomal phase in the heavy subfraction after the bile duct ligation. This subcellular change could be a consequence of secondary lipidosis: hepatocyte lysosomes have been exhausted in sorting accumulated lipids into secretory lipoproteins.     

Yes-associated protein regulates the hepatic response after bile duct ligation

Human chronic cholestatic liver diseases are characterized by cholangiocyte proliferation, hepatocyte injury, and fibrosis. Yes-associated protein (YAP), the effector of the Hippo tumor-suppressor pathway, has been shown to play a critical role in promoting cholangiocyte and hepatocyte proliferation and survival during embryonic liver development and hepatocellular carcinogenesis. Therefore, the aim of this study was to examine whether YAP participates in the regenerative response after cholestatic injury. First, we examined human liver tissue from patients with chronic cholestasis. We found more-active nuclear YAP in the bile ductular reactions of primary sclerosing cholangitis and primary biliary cirrhosis patient liver samples. Next, we used the murine bile duct ligation (BDL) model to induce cholestatic liver injury. We found significant changes in YAP activity after BDL in wild-type mice. The function of YAP in the hepatic response after BDL was further evaluated with liver-specific Yap conditional deletion in mice. Ablating Yap in the mouse liver not only compromised bile duct proliferation, but also enhanced hepatocyte necrosis and suppressed hepatocyte proliferation after BDL. Furthermore, primary hepatocytes and cholangiocytes isolated from Yap-deficient livers showed reduced proliferation in response to epidermal growth factor in vitro. Finally, we demonstrated that YAP likely mediates its biological effects through the modulation of Survivin expression. Conclusion: Our data suggest that YAP promotes cholangiocyte and hepatocyte proliferation and prevents parenchymal damage after cholestatic injury in mice and thus may mediate the response to cholestasis-induced human liver disease. (HEPATOLOGY 2012;56:1097-1107).     

Phenobarbital influences the development of sodium retention in liver disease induced by bile duct ligation in the rat

The onset of sodium retention in phenobarbital/carbon tetrachloride-induced cirrhosis in rats is preceded by a linear decrease in hepatic function as assessed by the aminopyrine rate constant of elimination. Sodium retention occurs when liver function decreases below a critical aminopyrine rate constant of elimination threshold of 1 min-1 x 10(-3). The objective of this study was to investigate this relationship in a different experimental model of cirrhosis in rats and to learn whether alteration of drug-metabolizing activity by hepatic enzyme induction changes the threshold for urinary sodium retention. Cirrhosis was induced in untreated and phenobarbital-treated rats by bile duct excision. Liver function, assessed by the aminopyrine breath test, and urinary sodium excretion on a constant salt diet were measured weekly for up to 4 wk. In untreated rats, the aminopyrine breath test rate constant of elimination was reduced by about 40% within 1 wk of surgery. Aminopyrine rate constant of elimination then decreased more slowly, but linearly. Urinary sodium excretion was initially unchanged, but sodium retention occurred after 2.5 wk and was maintained until the end of the experiment. Phenobarbital-treated rats had greater initial aminopyrine rate constant of elimination, but we saw a similar fall in aminopyrine rate constant of elimination of about 40% within 1 wk of bile duct excision to a value still above baseline aminopyrine rate constant of elimination of untreated controls. Aminopyrine rate constant of elimination remained at a plateau for 3.5 wk without changes in urinary sodium excretion. After 3.5 wk, a sudden decrease in aminopyrine rate constant of elimination was associated with the sudden onset of sodium retention.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ketorolac pharmacokinetics in experimental cirrhosis by bile duct ligation in the rat

The purpose of the present work was to study the pharmacokinetics of ketorolac, a poorly metabolized drug, in experimental cirrhosis. Cirrhosis was induced by bile duct ligation (BDL) for four weeks in male Wistar rats. Ketorolac was given intravenously (1 mg/kg ) or orally (3.2 mg/kg) to control (sham-operated) and BDL-rats. Determination of ketorolac in plasma was carried out by HPLC and estimation of pharmacokinetic parameters was performed by non-compartmental analysis. Indicators of liver damage and liver fibrosis were significantly increased (p < 0.05) in BDL compared to control rats. Experimental cirrhosis did not induce any significant alteration in intravenous ketorolac pharmacokinetics. Volume of distribution, clearance, AUC and t1/2 were similar in BDL and control animals. Notwithstanding, oral ketorolac bioavailability was significantly altered in BDL rats. AUC and Cmax were reduced, while tmax was prolonged, suggesting that both, the extent and the rate of ketorolac absorption were decreased. Results show that liver cirrhosis may result in significant pharmacokinetic alterations, even for poorly bio-transformed drugs, but that alterations may vary with the route of administration. In conclusion, uncritical generalizations on the effect of liver damage on drug kinetics should be avoided and systematic studies for every drug and every route of administration are thus recommended.     

Dietary glycine blunts liver injury after bile duct ligation in rats

AIM： To investigate the effects of （dietary） glycine against oxidant-induced injury caused by bile duct ligation （BDL）.
METHODS： Either a diet containing 5% glycine or a standard diet was fed to male Sprague-Dawley （SD） rats. Three days later, BDL or sham-operation was performed. Rats were sacrificed 1 to 3 d after BDL. The influence of deoxycholic acid （DCA） in the presence or absence of glycine on liver cells was determined by measurement of calcium and chloride influx in cultivated Kupffer cells and lactate dehydrogenase （LDH） activity was determined in the supernatant of cultivated hepatocytes.
RESULTS： Serum alanine transaminase levels increased to about 600 U/L 1 d alter BDL. However, enzyme release was blunted by about two third in rats receiving glycine. Release of the alkaline phosphatase and aspartate aminotransferase was also blocked significantly in the group fed glycine. Focal necrosis was observed 2 d after BDL. Glycine partially blocked the histopathological changes. Incubation of Kupffer cells with DCA led to increased intracellular calcium that could be blocked by incubation with glycine. However, systemic blockage of Kupffer cells with gadolinium chloride had no effects on transaminase release. Incubation of isolated hepatocytes with DCA led to a significant release of LDH after 4 h. This release was largely blocked when incubation with glycine was performed.
CONCLUSION： These data indicate that glycine significantly decreased liver injury, most likely by a direct effect on hepatocytes. Kupffer cells do not appear to play an important role in the pathological changes caused by cholestasis.     

Ursodeoxycholic acid limits liver histologic alterations and portal hypertension induced by bile duct ligation in the rat.

Chronic administration of ursodeoxycholic acid (UDCA) has recently been suggested as a potential treatment for cholestatic liver disease. The purpose of this study was to examine the effects of chronic oral administration of UDCA on the histological, biochemical, and hemodynamic abnormalities induced by bile duct ligation in the rat. Fifty-one rats with ligation-section of the common bile duct were randomly and blindly assigned to receive UDCA (25 mg/kg each day) or placebo by gavage for 4 weeks. At the end of the treatment period, morphometric analysis showed that in rats treated with UDCA, hepatocyte and sinusoidal volume fractions were significantly higher than in rats receiving placebo [41.9 +/- 3.2% vs. 28.1 +/- 1.8%, (mean +/- SE) and 7.4 +/- 0.1% vs. 4.3 +/- 0.3%, respectively], whereas bile duct volume fraction (reflecting bile ductular proliferation) and connective tissue fraction were significantly lower in rats treated with UDCA than in rats receiving placebo (14.2 +/- 1.5% vs. 20.0 +/- 1.0% and 35.4 +/- 2.4% vs. 47.6 +/- 1.7%, respectively). Serum aminotransferase and alkaline phosphatase activities, and total serum bile acids and individual bile acid concentrations were not significantly different between the two groups. Portal pressure (12.7 +/- 0.5 mm Hg vs. 17.1 +/- 0.5 mm Hg), portal tributary blood flow (5.7 +/- 0.4 vs. 9.3 +/- 0.4 mL.min-1.100 g-1 body weight), and cardiac index (41.1 +/- 1.8 vs. 50.6 +/- 1.4 mL.min-1.100 g-1 body weight) were significantly lower in UDCA-treated rats than in placebo-treated animals. In portal vein stenosed rats, chronic administration of UDCA had no hemodynamic effects, a finding that suggests UDCA has no direct vasoactive effect on splanchnic circulation. It is concluded that in rats with bile duct ligation UDCA limits the severity of liver disease and consequently of portal hypertension and hyperkinetic circulation.     

Impaired synthesis of retinol-binding protein and transthyretin in rat liver with bile duct obstruction

To gain further insight into the protein metabolism in bile duct-obstruction, we examined the synthesis of retinol-binding protein (RBP) and transthyretin (TTR) in rats with common bile duct-ligation. In these rats, liver and plasma levels of RBP and TTR decreased markedly, whereas liver retinoid contents remained unchanged. Although there appeared no decrease in the total amount of RBP or TTR mRNA expressed in the liver, the subcellular distribution of these mRNAs changed from the membrane-bound polysome fraction to the membrane-unbound polysome fraction. This abnormal distribution recovered rapidly after biliary drainage, resulting in the subsequent recovery of the plasma RBP and TTR levels. These observations suggest that cholestasis inhibits the synthesis and secretion of RBP and TTR by disrupting the binding of their mRNAs to membrane-bound polysomes. Plasma levels of RBP and TTR might be sensitive indicators of the recovery of protein synthesis after biliary drainage in patients with obstructive biliary disorders.Supported in part by Grant-in-Aids from the Ministry of Education, Science and Culture (05770350 to M.O.; 05670463 to H.M.; 07780553 to S.K.) and by a grant from the Ryoichi Naito Foundation for medical research (to S.K.).     

A quantitative analysis of the liver following ligation of the common bile duct

A quantitative analysis of the liver was performed at intervals of 24, 48, 72 and 96 h and 7, 21 and 50 days following total biliary obstruction (TBO) in the Sprague-Dawley rat. During this period, the liver weight increased from 7.72 +/- 0.51 g (mean +/- SEM) in controls to 24.57 +/- 1.66 g (p less than 0.0005) at 50 days. There was a concomitant reduction in the volume proportion of the liver occupied by liver cells, from 71.37 +/- 1.36% to 21.54 +/- 3.27% (p less than 0.0005), but there were increases in the volume proportions of biliary epithelial cells (BEC) from 0.14 +/- 0.02% to 16.39 +/- 1.12% (p less than 0.0005), of other cell and tissue types from 5.50 +/- 4.89% to 30.73 +/- 2.42% (p less than 0.0005) and of vascular and biliary channel spaces from 22.99 +/- 1.17% to 31.35 +/- 0.87% (p less than 0.0025). In control animals, the liver cell and BEC volume was estimated to be 6240 +/- 360 microns 3 and 100 +/- 10 microns 3, respectively. Following TBO, the liver cell volume was significantly greater than control only from 48-96 h, whereas the BEC increased significantly in volume from 24 to 72 h and then remained approximately 6 times the control value until the end of the period of study. Contrary to the histological appearance and decrease observed in volume proportion, the total liver cell population did not significantly differ from the control value of 8.83 x 10(8) +/- 0.80 x 10(8) cells, other than at 21 days when it increased to 14.90 x 10(8) +/- 1.04 x 10(8) cells (p less than 0.05). When expressed as the number of liver cells/100 g b.wt., an increase from the control value of 4.37 x 10(8) +/- 0.32 x 10(8) cells was observed only at 7 (5.66 x 10(8) +/- 0.42 x 10(8) cells; p less than 0.05) and 21 days (6.94 x 10(8) +/- 0.48 x 10(8) cells; p less than 0.05). This maintenance of liver cell population, following biliary obstruction, at or above the control values matches the clinical observation of preserved liver cell function. The total BEC population in control livers was 1.11 x 10(8) +/- 0.20 x 10(8) cells. A significant increase in this population was observed at 7 days (3.82 x 10(8) +/- 0.62 x 10(8) cells; p less than 0.05) with further increases to 57.90 x 10(8) +/- 6.42 x 10(8) cells (p less than 0.05) at 50 days, 52 times the control value. When expressed as cells/100 g b.wt., similar changes were observed. The results reported here indicate the importance of taking into account the change in the entire organ size and total mass of the cells in question when assessing alterations in their number.     

Effect of sensory denervation with capsaicin on liver fibrosis induced by common bile duct ligation in rat

Hepatic fibrosis represents an important stage in the progression of chronic liver disease to cirrhosis. In the present paper we have investigated whether capsaicin-sensitive neuropeptide-containing sensory neurons may participate in the development of liver fibrosis. The expression of hepatic fibrosis induced by common bile duct obstruction has been studied both in capsaicin- and vehicle-treated rats. Common bile duct-induced liver fibrosis was less marked in capsaicin-treated rats than in vehicle-treated rats. Diffuse alterations of liver parenchyma structure with marked collagen deposition and nodular regeneration occurred 8 weeks after common bile duct ligation in vehicle-treated animals, while none of the capsaicin-treated rats exhibited the formation of complete connective septa altering the parenchyma architecture. Both vehicle- and capsaicin-treated rats showed an increasing number of desmin-positive cells in the perivenular zone, but the density of these cells was lower in treated animals than in untreated rats. The hydroxyproline content of the liver increased after common bile duct ligation in a time-dependent manner. Eight weeks after bile duct obstruction vehicle-treated rats showed a 7-fold increase of liver collagen content in comparison to normal animals. This enhancement was about 3.5-fold in capsaicin-treated rats. These findings raise the possibility that the peripheral release of neuropeptides stored in sensory nerves might participate in the development of liver fibrosis following common bile duct obstruction.     

Kupffer cells alter organic anion transport through multidrug resistance protein 2 in the post-cold ischemic rat liver

Although Kupffer cells (KCs) may play a crucial role in post-cold ischemic hepatocellular injury, their role in nonnecrotic graft dysfunction remains unknown. This study examined reveal the role of KC in post-cold ischemic liver grafts. Rat livers treated with or without liposome-encapsulated dichloromethylene diphosphonate, a KC-depleting reagent, were stored in University of Wisconsin (UW) solution at 4 degrees C for 8 to 24 hours and reperfused while monitoring biliary output and constituents. The ability of hepatocytes to excrete bile was assessed through laser-confocal microfluorography in situ. Cold ischemia-reperfused grafts decreased their bile output significantly at 8 hours without any notable cell injury. This event coincided with impaired excretion of glutathione and bilirubin-IXalpha (BR-IXalpha), suggesting delayed transport of these organic anions. We examined whether intracellular relocalization of multidrug resistance protein-2 (Mrp2) occurred. Kinetic analyses for biliary excretion of carboxyfluorescein, a fluoroprobe excreted through this transporter, revealed significant delay of dye excretion from hepatocytes into bile canaliculi. The KC-depleting treatment significantly attenuated this decline in biliary anion transport mediated through Mrp2 in the 8-hour cold ischemic grafts via redistribution of Mrp2 from the cytoplasm to the canalicular membrane. Furthermore, thromboxane A(2) (TXA(2)) synthase in KC appeared involved as blocking this enzyme improved 5-carboxyfluorescein excretion while cytoplasmic internalization of Mrp2 disappeared in the KC-depleting grafts. In conclusion, KC activation is an important determinant of nonnecrotic hepatocellular dysfunction, jeopardizing homeostasis of the detoxification capacity and organic anion metabolism of the post-cold ischemic grafts.     

RKIP在胆总管结扎肝纤维化大鼠肝脏组织的表达

目的 研究RKIP在胆总管结扎肝纤维化大鼠肝脏组织中的表达.方法 SD大鼠60只,随机分为模型组(48只)、对照组(12只).运用胆总管结扎方法 制作大鼠肝纤维化模型,模型组分别于结扎后1、2,3、4 w麻醉动物,假手术组与4 w模型组同批麻醉,留取肝脏标本.组织切片经HE和Masson三色染色检测病理变化,westem印迹和免疫组织化学方法 检测RKlP在肝组织的表达,用westem印迹方法 检测RKIP和ERK的磷酸化水平.结果 HE和Masson三色染色结果 证明胆总管结扎大鼠肝纤维化模型制作成功.随着肝纤维化程度增高RKIP表达下降,RKIP和ERK的磷酸化水平则相应增加.结论 胆总管结扎大鼠肝纤维化过程中肝脏组织Raf-1/MEK/ERKl,2信号转导途径的激活与RKIP的蛋白表达下降和磷酸化增加有关.     

Effects of bile duct ligation and cholic acid treatment on fatty liver in two rat models of non-alcoholic fatty liver disease

Background

Non-alcoholic fatty liver disease, one of the most prevalent liver disorders in Western countries, is characterized by hepatic accumulation of triglycerides. Bile acids have long been known to affect triglyceride homeostasis through a not completely understood mechanism.

Aim

To analyse the effects of two different manipulations of bile acid circulation on non-alcoholic fatty liver disease.

Methods

Two animal models of non-alcoholic fatty liver disease were developed by either feeding rats with a choline deficient or with a high fat diet. After 4 weeks, rats were randomized to undergo either bile duct ligation, sham operation or cholic acid administration.

Results

During cholestasis there was an increased CYP7A1 expression, the rate limiting enzyme in bile acid synthesis, and a reduction of hepatic concentration of oxysterols, ligands of the liver X receptors. Target genes of the liver X receptors, involved in fatty acid and triglyceride synthesis, were down-regulated in association with decreased hepatic triglyceride content and improvement of fatty liver. Administration of cholic acid, ligand of farnesoid X receptor, also had a beneficial effect on fatty liver in rats on choline deficient diet.

Conclusion

These results indicate that pharmacological approaches increasing the expression of CYP7A1 or stimulating farnesoid X receptor pathway could represent a promising treatment for non-alcoholic fatty liver disease.     

Effect of ZVAD-fmk on hepatocyte apoptosis after bile duct ligation in rat

AIM: Retention and accumulation of toxic hydrophobic bile salts within hepatocyte may cause hepatocyte toxicity by inducing apoptosis. Apoptosis is a pathway of cell death orchestrated by a family of proteases called caspases. Z-Val-Ala-Asp (OMe)-fluoromethyl ketone (ZVAD-fmk) is a cell-permeable irreversible inhibitor of caspase. The purpose of this study was to evaluate the possible effect of ZVAD-fmk on hepatocyte apoptosis after bile duct ligation in the rat. METHODS: Male Sprague-Dawley rats, weighing 250-300 g, were randomized to five groups of five rats each. Group 1 underwent common bile duct ligation and simultaneous treatment with ZVAD-fmk (dissolved in dimethylsulfoxide (DMSO)). Group 2 underwent common bile duct ligation and simultaneous treatment with Z-Phe-Ala-fluoromethyl ketone (ZFA-fmk, dissolved in DMSO). Group 3 underwent sham operation and simultaneous treatment with the same amount of DMSO. Group 4 underwent sham operation and simultaneous treatment with the same amount of normal saline. Group 5 underwent common bile duct ligation without other manipulation. After three days, liver tissue was harvested for histopathologic analysis and measurements of apoptosis. RESULTS: When compared with sham operation, common bile duct ligation significantly increased hepatocyte apoptosis (P= 0.008) and ductular proliferation (P= 0.007). ZVAD-fmk significantly diminished the increased hepatocyte apoptosis and ductular proliferation after common bile duct ligation (P= 0.008 and P= 0.007, respectively). ZFA did not show the same effects. CONCLUSION: Hepatocyte apoptosis and ductular proliferation significantly increased after common bile duct ligation. ZVAD-fmk effectively diminished the increased hepatocyte apoptosis and ductular proliferation after common bile duct ligation, whereas ZFA-fmk did not.     

Relationships between NOS2 and HO-1 in liver of rats with chronic bile duct ligation.

An increased expression and activity of the heme oxygenase-1 (HO-1) in the liver has been observed in models of hepatic damage. Nitric oxide (NO) seems to be involved in HO-1 regulation. The aim of this work is to assess HO-1 induction and heme oxygenase (HO) activity in rats with bile duct ligation (BDL). We have assessed the effect of chronic inhibition of the NO synthesis by N(G)-nitro-l-arginine methyl ester (l-NAME) on HO-1 induction and HO activity. In the BDL animals, compared with sham-operated ones, we found an increased plasma nitrite and bilirubin concentration, and a marked liver expression of inducible nitric oxide synthase and HO-1, assessed by both Western blot and immunohistochemistry. Chronic l-NAME treatment prevented plasma nitrite increase in animals subjected to BDL. BDL animals treated with l-NAME, compared with untreated BDL rats, showed an important decrease in HO-1 expression and in HO activity (assessed as a decreased plasma bilirubin and bilirubin excretion). In conclusion, our experiments show parallel changes in expression and activity of HO-1 and NOS2 activity in the BDL model of liver damage and suggest that increased NO production is involved in HO-1 overexpression.     

Antifibrotic effect of N-acetyl-seryl-aspartyl-lysyl-proline on bile duct ligation induced liver fibrosis in rats

AIM:To investigate the preventive effect of N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) on bile duct ligation (BDL)induced liver fibrosis in rats. METHODS:Liver fibrosis in rats was induced by BDL and AcSDKP was infused subcutaneously for 2 wkvia a osmotic minipump (Alzet 2ML4) immediately after BDL operation. After scarifying, serum and liver specimens were collected. Hematoxylin and eosin staining, Sirius red staining, enzyme linked immunosorbent assay, Western blot or real-time polymerase chain reaction were used to determinate liver functions, histological alterations, collagen deposition, mRNA expression of markers for fibroblasts, transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein-7 (BMP-7). RESULTS:When compared to model rats, chronic exogenous AcSDKP infusion suppressed profibrogenicTGF-β1 signaling, α-smooth muscle actin positivity (α-SMA), fibroblast specific protein-1 (FSP-1) staining and collagen gene expression. Col Ⅰ, Col Ⅲ, matrix metalloproteinase-2, tissue inhibitors of metallopro-teinase-1 and tissue inhibitors of metalloproteinase-2 mRNA expressions were all significantly downregulated by AcSDKP infusion (2.02 ± 1.10vs 14.16 ± 6.50, 2.02 ± 0.45vs 10.00 ± 3.35, 2.91 ± 0.30vs 7.83 ± 1.10, 4.64 ± 1.25 vs 18.52 ± 7.61, 0.46 ± 0.16 vs 0.34 ± 0.12, respectively, P 0.05). Chronic exogenous AcSDKP infusion attenuated BDL-induced liver injury, inflammation and fibrosis. BDL caused a remarkable increase in alanine transaminase, aspartate transaminase, total bilirubin, and prothrombin time, all of which were reduced by AcSDKP infusion. Mast cells, collagen accumulation, α-SMA, TGF-β1, FSP-1 and BMP-7 increased. The histological appearance of liver specimens was also improved. CONCLUSION:Infusion of exogenous AcSDKP attenu-ated BDL-induced fibrosis in the rat liver. Preservation of AcSDKP may be a useful therapeutic approach in the management of liver fibrosis.     

The mechanism of elevated alkaline phosphatase activity after bile duct ligation in the rat

Alkaline phosphatase activity in the liver and intestine increases after bile duct ligation, reportedly by increased enzyme synthesis. To ascertain the mechanism of this increased synthesis in the absence of a cDNA clone encoding the enzyme, we have estimated the concentration of liver and intestinal alkaline phosphatase mRNA by translational analysis. Monospecific antiserum to rat placental alkaline phosphatase was raised. The resulting antiserum precipitated two peptides of 53 and 56 kd after translation of liver poly(A) + RNA. The precipitation of both peptides was blocked by the single 64 kd placental alkaline phosphatase. Processing of the cell-free products by microsomal membranes produced peptides of 62 and 64 kd. Antiserum to rat intestinal alkaline phosphatase also identified two peptides as products of intestinal RNA translation. After bile duct ligation, we confirmed a transient 2-fold increase in alkaline phosphatase activity in the intestine and a more constant 7-fold increase in the liver. However, the alkaline phosphatase mRNA concentration remained unchanged in both organs. We conclude that increased alkaline phosphatase synthesis after bile duct ligation results from an enhanced rate of translation of mRNA.     

梗阻性黄疸大鼠肝细胞MRP2和FXR蛋白表达变化及意义分析

目的通过建立梗阻性黄疸动物模型，在蛋白水平观察多耐药相关蛋白MRP2（muhidrug resistance-associated protein2，MRP2）和类法尼醇X受体FXR（farnesoid X receptor）表达变化并分析二者之间的关系。方法用胆总管结扎术方法制备大鼠梗阻性黄疸模型，检测肝功能；提取大鼠肝细胞膜蛋白与核蛋白，测定提取液蛋白浓度；采用Westernblot技术检测MRP2和FXR蛋白表达。结果梗阻性黄疸大鼠总胆红素、直接胆红素显著升高；与假手术对照组相比，梗阻性黄疸组大鼠肝细胞MRP2蛋白表达明显降低（P=0．041），FXR蛋白无表达，差异均有统计学意义。结论MRP2表达下调可能与FXR表达抑制有关，FXR蛋白可能对MRP2蛋白表达有正性调控作用。     

Cell proliferation and oncogene expression after bile duct ligation in the rat: Evidence of a specific growth effect on bile duct cells

The proliferative response of the rat liver was measured after temporary or permanent total biliary obstruction (BDO) and in different regions after selective ligation of the lobar ducts draining the right 60% of the hepatic mass. The results were compared with those after 70% partial hepatectomy (PH). Cell proliferation was assessed globally by measuring DNA synthesis and stratified to the separate cell populations with cytostaining techniques that allowed distinction of hepatocytes, duct cells, and nonparenchymal cells (NPCs). In selected experimental groups, gene expression was determined of transforming growth factor-β1 (TGFβ-1), prothrombin, c-erb-B2, transforming growth factor alpha (TGFα), human Cyclophilin (CyP), and 28S ribosomal RNA. The stimulation of a proliferative response to total BDO required obstruction for longer than 24 hours, but after this deligation did not switch off regeneration. In the first week after permanent BDO, there was progressive infiltration of NPCs, fibrous linkage of some portal areas, and a crescendo of DNA synthesis that was obvious at 24 hours, maximal at 48 hours, and back nearly to baseline at 6 days. At the 2-day mark, the bile duct cells had a 17-fold increase in proliferation, accompanied by a threefold to fourfold increase in hepatocyte renewal. Little or no increase in expression of TGFα or the hepatocyte-specific prothrombin gene was detectable in the first 48 hours, whereas levels of the oncogene c-erb-B2 that is associated with cholangiocarcinoma were expressed from 48 to 96 hours. Livers subjected to regional BDO with or without immunosuppressive treatment with FK 506 and cyclosporine had an inflammatory reaction only on the side with ligated ducts. DNA synthesis increased in both the obstructed and freely draining lobes to approximately half the level that occurred after total BDO. The proliferation of the obstructed side was similar to the mixed duct cell/hepatocyte response after total BDO, but this almost exclusively involved duct cells on the freely draining side. In contrast to the findings after BDO, livers after PH regenerated maximally at 24 hours rather than 48 hours, had a predominantly noninflammatory hepatocyte as opposed to duct cell response, and had marked expression of the prothrombin and TGFα genes but only weakly and late of c-erb-B2 messenger RNA. The results show that the liver responds as a whole and in a biologically intelligent way to the nature of the injury inflicted on any part of it. It further implies the presence of humoral communications and control networks that assure organ homeostasis and relate this to total body homeostasis.