Volume 122, Issue 4, Pages 1058-1069 (April 2002) Corticosteroids modulate the secretory processes of the rat intrahepatic biliary epithelium  Domenico Alvaro, Alessandro Gigliozzi, Luca Marucci, Gianfranco Alpini, Barbara Barbaro, Rita Monterubbianesi, Lara Minetola, Maria Grazia Mancino, Juan F. Medina, Adolfo F. Attili, Antonio Benedetti  Gastroenterology  Volume 122, Issue 4, Pages 1058-1069 (April 2002) DOI: 10.1053/gast.2002.32374 Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 1 Immunohistochemistry for GcR in liver sections from normal, dexamethasone-treated, and 1-week BDL rats. (A) In normal liver, a specific reaction appears in the cytoplasm mostly in the apical area and in the perinuclear region of cholangiocytes (curved arrow). (B) After BDL, a pronounced nuclear positivity (arrow) as well as a diffuse cytoplasmic staining are evident. (C) A stronger nuclear and cytoplasmic positivity is evident in sections of dexamethasone-treated rats. In all situations, a positive reaction is also present in cells of the surrounding connective tissue (arrowhead) and hepatocytes (star). Control sections taken from (A1) normal, (B1) 1-week BDL, and (C1) dexamethasone-treated rats and incubated with the primary antibody neutralized by preabsorption with the blocking peptide show absence of specific staining. L, lumen. Original magnification 250×. Gastroenterology 2002 122, 1058-1069DOI: (10.1053/gast.2002.32374) Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 2 (A) Cholangiocytes from both normal and BDL rats were examined for the presence of the message for GcR and GAPDH (the housekeeping gene) by RT-PCR. The message for GcR was expressed by normal cholangiocytes and up-regulated in cholangiocytes from BDL rats. GAPDH gene expression, which assures the comparability of the total mRNA used, was similar among normal and hyperplastic cholangiocytes from BDL rats. Poly (A)+ mRNA from rat brain and yeast transfer RNA were the positive and negative controls, respectively. Representative experiment of n = 2. (B) Western blot analysis of GcR in cholangiocytes isolated from normal rats (N), rats treated for 2 days with dexamethasone (N+Dexa.), and BDL rats. Bar graph shows the percent increase of protein mass in comparison with normal rats. Data are mean ± SE of n = 3. *P < 0.05 vs. normals. Gastroenterology 2002 122, 1058-1069DOI: (10.1053/gast.2002.32374) Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 3 Effect of (A) acute or (B) chronic administration of corticosteroids on bile flow and bicarbonate biliary excretion in normal and BDL rats. (A) Dexamethasone (5 μmol/L, n = 10) or budesonide (1 μmol/L, n = 6) administered for 40–80 minutes through the jugular vein in normal (left) or 2-week BDL (right) bile fistula rats showed no significant effect on bile flow and bicarbonate biliary excretion. In addition, no significant changes were observed when the 2 corticosteroids were interrupted. (B) A 2-day treatment of normal rats with dexamethasone (DEXA. 0.9 mg/3 times daily, subcutaneously; n = 12) or budesonide (BUDE. 0.15 mg/3 times daily, subcutaneously; n = 12) induced a significant increase of bile flow (left) and bicarbonate biliary excretion (right) compared with controls (C; n = 10) administered with the carrier alone (i.e., DMSO+KRB). Rats treated with dexamethasone + RU-486 (n = 10), a specific GcR antagonist, showed a similar bile flow and bicarbonate biliary excretion to controls and significantly (P < 0.05) lower levels compared with rats treated with dexamethasone alone. *P < 0.05 vs. controls; &P < 0.05 vs. dexamethasone. Data are mean ± SE. Gastroenterology 2002 122, 1058-1069DOI: (10.1053/gast.2002.32374) Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 4 Effect of a 2-day treatment with dexamethasone on the activity of the (A) Cl−/HCO3− and (B) Na+/H+ exchangers in IBDU. (A) Two consecutive acute Cl− removal/readmission maneuvers were performed, the second during superfusion with 50 nmol/L secretin. The maximal rate of pHi alkalinization after Cl− removal and the maximal rate of pHi recovery after Cl− readmission were higher (P < 0.05) after treatment with dexamethasone (top) than controls (bottom), both in basal conditions and during secretin superfusion. (B) IBDU cultured and perfused with solutions nominally free of bicarbonate (L15 and HEPES, respectively). The recovery rates from NH4Cl-induced acidification were higher (P < 0.05) when measured in IBDUs from rats treated with dexamethasone (top) than from control rats (bottom). When EIPA was administered, only marginal pHi recovery was seen indicating that, in HEPES, the Na+/H+ exchanger was the only transporter involved in pHi recovery. Experiments are representative of data reported in Tables 1 and 2. Gastroenterology 2002 122, 1058-1069DOI: (10.1053/gast.2002.32374) Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 5 Effect of 2 days administration of dexamethasone on the protein level of AE2, NHE1, Na+/K+-ATPase, Na+/K+/2Cl−, and CFTR in (A) isolated cholangiocytes and (B) isolated hepatocytes. (A) Western blot analyses of the AE2 member of the Cl−/HCO3− exchanger, NHE1 isoform of the Na+/H+ exchanger, Na+/K+-ATPase, Na+/K+/2Cl−, and CFTR in cholangiocytes isolated from (C) control rats or (D) rats treated for 2 days with dexamethasone. Bar graphs show the percent increase of protein mass in comparison with controls, which was significant for AE2 and NHE1 but not for Na+/K+-ATPase, Na+/K+/2Cl−, and CFTR. *P < 0.05 vs. controls. Data are mean ± SE of n = 3. (B) Western blot analyses of the NHE1 isoform of the AE2 member of the Cl−/HCO3− exchanger and NHE1 isoform of the Na+/H+ exchanger in hepatocytes isolated from control rats (C) or rats treated for 2 days with dexamethasone (D). Bar graphs show the percent increase of protein mass in comparison with controls, which was not significant. Data are mean ± SE of n = 3. Gastroenterology 2002 122, 1058-1069DOI: (10.1053/gast.2002.32374) Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 6 Effect of 2 days of administration of dexamethasone on AE2, NHE1, and secretin receptor mRNA levels in isolated cholangiocytes (ribonuclease protection assays). mRNA level for NHE1 but not AE2 or SR in isolated cholangiocytes was increased (*P < 0.05) by 2 days of treatment with dexamethasone with respect to controls. GAPDH was used as housekeeping gene. Bar graph shows percent changes of mRNA level of (D) dexamethasone-treated rats in comparison with (C) controls. Data are mean ± SE of n = 3. Gastroenterology 2002 122, 1058-1069DOI: (10.1053/gast.2002.32374) Copyright © 2002 American Gastroenterological Association Terms and Conditions