RESUMO
We posed these questions: (i) Does administration of gastrin to 1-week bile duct ligation (BDL) rats inhibits established cholangiocyte proliferation and ductal secretion? (ii) Is gastrin inhibition of cholangiocyte proliferation and secretion of BDL rats associated with enhanced apoptosis? (iii) Are gastrin's effects on cholangiocyte function associated with increased expression of protein kinase C (PKC) isoforms; and (iv) Is gastrin stimulation of cholangiocyte apoptosis regulated by the Ca2+-dependent PKC pathway? METHODS: Seven days after BDL, rats were treated with gastrin by minipumps for 14 days. Cholangiocyte proliferation was assessed by measurement of the number of PCNA and CK-19 positive cholangiocytes in sections, and PCNA expression in cholangiocytes. Ductal secretion was determined by measurement of secretin-induced cAMP levels and choleresis. Apoptosis was evaluated by TUNEL analysis in sections and annexin-V staining in cholangiocytes. The expression of PKC isoforms was determined by immunoblots. RESULTS: Gastrin inhibits established cholangiocyte proliferation and enhanced secretin-stimulated ductal secretion of BDL rats.Gastrin's effects on cholangiocyte function were associated with enhanced apoptosis and increased expression of PKC alpha, and beta I and II. Gastrin increases in cholangiocyte apoptosis were blocked by BAPTA/AM and H7. SUMMARY/CONCLUSION: Gastrin inhibits cholangiocyte proliferation and secretin-induced ductal secretion in BDL rats by increasing apoptosis through a PKC-mediated mechanism.
Assuntos
Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Ductos Biliares/citologia , Cálcio/metabolismo , Gastrinas/administração & dosagem , Proteína Quinase C/biossíntese , Proteína Quinase C/efeitos dos fármacos , Secretina/administração & dosagem , Animais , Biomarcadores/análise , Divisão Celular/efeitos dos fármacos , AMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/fisiologia , Isoenzimas/biossíntese , Isoenzimas/efeitos dos fármacos , Ligadura , Masculino , Modelos Animais , Antígeno Nuclear de Célula em Proliferação/efeitos dos fármacos , Antígeno Nuclear de Célula em Proliferação/metabolismo , Ratos , Ratos Endogâmicos F344 , Estatística como AssuntoRESUMO
Bile acids are cytoprotective in hepatocytes by activating phosphatidylinositol-3-kinase (PI3-K) and its downstream signal AKT. Our aim was to determine whether feeding taurocholate to CCl(4)-treated rats reduces cholangiocyte apoptosis and whether this cytoprotective effect is dependent on PI3-K. Cholangiocyte proliferation, secretion, and apoptosis were determined in cholangiocytes from bile duct ligation (BDL), CCl(4)-treated BDL rats, and CCl(4)-treated taurocholate-fed rats. In vitro, we tested whether CCl(4) induces apoptosis and whether loss of cholangiocyte proliferation and secretion is dependent on PI3-K. The CCl(4)-induced cholangiocyte apoptosis and loss of cholangiocyte proliferation and secretion were reduced in CCl(4)-treated rats fed taurocholate. CCl(4)-induced cholangiocyte apoptosis, loss of cholangiocytes secretion, and proliferation were prevented by preincubation with taurocholate. Taurocholate cytoprotective effects were ablated by wortmannin. Taurocholate prevented, in vitro, CCl(4)-induced decrease of phosphorylated AKT protein expression in cholangiocytes. The cytoprotective effects of taurocholate on CCl(4) effects on cholangiocyte proliferation and secretion were abolished by wortmannin. Taurocholate protects cholangiocytes from CCl(4)-induced apoptosis by a PI3-K-dependent mechanism. Bile acids are important in the prevention of drug-induced ductopenia in cholangiopathies.
