Thus, loss of p-catenin limits cholestatic injury by modulating BA biosynthesis through regulation of FXR. These findings support an important role of Wnt/p-catenin signaling in bile duct homeostasis and repair and provide novel therapeutic opportunity of modulating p-catenin signaling for alleviating BA-associated hepatic injury during cholestasis. Disclosures: Satdarshan
(Paul) S. Monga – Consulting: Bristol Myers Squibb, Phase Rx, Merck The following people have nothing to disclose: Kari Nejak-Bowen, Michael Thompson During DMXAA concentration cholestasis the balance between biliary growth/loss is regulated by neuroendocrine peptides and neurotransmitters by autocrine/paracrine and endocrine pathways. Gonadotropin-releasing hormone (GnRH) is a trophic peptide hormone (released from the hypothalamus) regulating reproductive functions in mammals. GnRH also alters the function of extra-pituitary non-reproductive organs such as the kidneys and pancreas. Since no data exists regarding the role of GnRH in regulating biliary homeostasis, we aimed to evaluate if GnRH regulates biliary growth in normal and bile duct ligated (BDL) rats by interacting with GnRH receptor (GnRHR). Methods: The studies were performed in: (i) normal rats treated with saline or GnRH (1 μg/day); BIBW2992 and (ii) BDL rats that, immediately after surgery, were treated with non-immune serum or anti-GnRH antibody (300μg/day) for
1 wk. Then, we measured: (i) intrahepatic bile duct mass (IBDM) in liver sections; and CK-19 and PCNA expression in total liver and cholangiocytes; and (ii) serum levels of GnRH by EIA kits. We measured the expression of: (i) GnRH and GnRHR in liver sections and cholangiocytes from normal and BDL rats and biliary lines by immunofluorescence, qPCR or immunoblots; and (ii) the levels of GnRH in the medium 上海皓元医药股份有限公司 of short-term (12 hr) cultures of cholangiocytes from normal and BDL rats and
biliary lines by EIA kits. In vitro, the: (i) dose- (10, 50 and 100 nM) and time- (24 to 72 hr) dependent effects of GnRH (in the absence/presence of the GnRHR antagonist, Cetrorelix acetate, 5-10 μM); and (ii) effect of Cetrorelix acetate (5-10 μM) on the proliferation of biliary lines was measured by MTS assays. GnRH expression was transiently knocked-down in biliary lines using siRNA and cell proliferation was assessed by MTS assays. Results: GnRH and GnRHR are expressed by normal bile ducts, cholangiocytes and biliary cell lines. GnRH biliary expression increased after BDL. Cholangiocytes secrete GnRH and, after BDL, GnRH secretion increased. Administration of GnRH to normal rats increased GnRH serum levels, biliary proliferation and IBDM, whereas administration of anti-GnRH antibody to BDL rats reduced biliary proliferation and IBDM. GnRH induced a dosedependent increase in biliary proliferation that was reduced by Cetrorelix acetate. Silencing of GnRH decreased the proliferation of biliary lines.