ESTROGEN RECEPTOR IS INVOLVED IN THE IMPAIRMENT OF BILE SALT SECRETION INDUCED BY ESTRADIOL-17ß-GLUCURONIDE IN ISOLATED RAT HEPATOCYTE COUPLETS

ISMAEL BAROSSO; ANDRES ZUCCHETTI; DIEGO TABORDA; ENRIQUE SANCHEZ POZZI; FERNANDO CROCENZI

Copenague

Congreso; International Liver Congress 2009 44 Annual Meeting of the European Association for the Study of the Liver; 2009

The European Association for the Study of the Liver

The endogenous estradiol metabolite, estradiol 17 beta-D-glucuronide (E17G), induces an acute cholestasis in rat liver due in part to retrieval of canalicular transporters such as the bile salt export pump (Bsep, Abcc11) in a process that involves PKC alpha (Hepatology 2008, 48: 1885-95). Recently, estrogen receptors (ER) have been  implicated in the chronic estrogen cholestasis model induced by ethynylestradiol (JBC 2006, 281:16625-31). The aim of this study was to evaluate the involvement of ER in E17G-induced changes in bile salt canalicular excretion.Methods: Isolated rat hepatocytes couplets were cultured for 5 h, exposed to the estrogen receptor inhibitor ICI-182,780 (ICI, 1 µM) for 15 min and then incubated with E17G (50 µM) for 20 min. Other couplet preparations were additionally incubated with PKC inhibitor Gö 6976 (Gö, 1 µM, 15 min) before E17G incorporation. Finally, all preparations were incubated with cholyl-lysylfluorescein (CLF) a fluorescent bile salt substrate of Bsep. Couplets accumulating CLF in their vacuole were counted in a fluorescent microscope and informed as a percentage. Results were compared by ANOVA followed by Student-Newman-Keuls test.Results:Control    Gö         ICI    E17G    E17G+Gö    E17G+ICI  E17G+ICI+Gö  54±5    53±4        53±4   32±3a     42±3b      44±7b      43±2b[% Couplets accumulating CLF]a significantly different from Control (p< 0.01);b significantly different from Control and E17G (p< 0.05). n=3Conclusions: ER inhibition prevents E17G-induced alteration in bile salt excretion. Selective blockage of PKC alpha activation with Gö6976 protects from E17G effects but did not increased the estrogen inhibitor action. These findings support a role for ER in E17G-induced cholestasis probably in a pathway that involves PKC alpha activation since the effects were not additive.