Estrogen receptor is involved in the impairment of bile salt secretion induced by estradiol 17ß-glucuronide in isolated rat hepatocyte couplets

BAROSSO, IR; ZUCCHETTI, AE; TABORDA, DR; SÁNCHEZ POZZI, EJ; CROCENZI, FA

Copenhague

Congreso; International Liver Congress 2009 (EASL); 2009

European Association for the Study of the Liver

The endogenous estradiol metabolite, estradiol 17β-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 (% AC). Results were compared by ANOVA followed by Student-Newman-Keuls test.Results: n=3          Control    Gö      ICI     E17G   E17G+Gö  E17G+ICI  E17G+ICI+Gö% AC   54±5     53±4   53±4  32±3a      42±3b        44±7b        43±2ba significantly different from Control (p<0.01); b significantly different from Control and E17G (p<0.05)Conclusions: 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.