Hormonal modulation of hepatic cAMP prevents estradiol 17ß-D-glucuronide induced cholestasis in perfused rat liver.

ZUCCHETTI, AE; BAROSSO, IR; BOAGLIO, AC; LUQUITA, MG; ROMA, MG; CROCENZI, FA; SÁNCHEZ POZZI, EJ

DIGESTIVE DISEASE AND SCIENCES

SPRINGER

Lugar: Berlin; Año: 2013 vol. 58 p. 1602 - 1614

0163-2116

Estradiol-17β-D-glucuronide (E17G) induces cholestasis in vivo, being endocytic internalization of the canalicular transporters multidrug-resistance associated protein 2 (Abcc2) and bile salt export pump (Abcb11) a key mechanism. cAMP prevents this cholestasis by targeting these transporters to the canalicular membrane. In hepatocyte couplets, glucagon and salbutamol, which increase cAMP, prevented E17G actions stimulating the traffic of transporters by different mechanisms. Glucagon activates a Protein Kinase A-dependent pathway whereas salbutamol activates an Exchange-protein activated by cyclic-AMP (Epac)-microtubule-dependent pathway. The present study evaluated whether glucagon and salbutamol prevent E17G-induced cholestasis in a more physiological model, the perfused rat liver (PRL). Additionally, preventive effect of in vivo alanine administration, which induces pancreatic glucagon secretion, was evaluated. In PRL, glucagon and salbutamol prevented E17G-induced decrease of bile flow and secretory activity of Abcc2 and Abcb11. Salbutamol prevention fully depended on microtubule integrity whereas glucagon prevention was only lately affected by colchicine. E17G also induced endocytic internalization of Abcb11 and Abcc2, which partially colocalized with the endosomal marker Rab11a. This effect was completely prevented by salbutamol, whereas some transporter-containing vesicles remained colocalizing with Rab11a after treatment with glucagon. In vivo, alanine administration increased hepatic cAMP and protected from cholestasis. Its early effects were microtubule-independent, but after 60 min of E17G administration, colchicine pretreatment inhibited alanine anticholestatic effects. We conclude that hormonal modulation of cAMP levels by direct administration of cAMP modulators or by physiological manipulations, like alanine administration, prevent estrogen-induced cholestasis in models with preserved liver architecture, by mechanisms similar to those postulated from in vitro studies.