title: Genipin enhances Mrp2 (Abcc2)-mediated bile formation and organic anion transport in rat liver.
abstract: Inchin-ko-to (ICKT), an herbal medicine, and its ingredients exert potent choleretic effects by a "bile acid-independent" mechanism. The current study was designed to determine whether ICKT or its ingredients potentiate multidrug resistance-associated protein 2 (Mrp2; Abcc2)-mediated choleresis in vivo. Biliary secretion of Mrp2 substrates and the protein mass, subcellular localization, and messenger RNA (mRNA) level of Mrp2 were assessed in rat liver after infusion of genipin, an intestinal bacterial metabolite of geniposide, a major ingredient of ICKT. The function of Mrp2 was also assessed by the adenosine triphosphate (ATP)-dependent uptake of Mrp2-specific substrates using canalicular membrane vesicles (CMVs) from the liver. Infusion of genipin increased bile flow by 230%. It also increased biliary secretion of bilirubin conjugates and reduced glutathione (GSH) by 513% and 336%, respectively, but did not increase bile acid secretion. The ATP-dependent uptake of estradiol 17-beta-D-glucuronide (E(2)17 beta G; by 265%), leukotriene C4 (LTC(4); by 161%), taurolithocholate-3-sulfate (TLC-3S; by 266%), and methotrexate (MTX; by 234%) was significantly stimulated in the CMVs from the liver. These effects were not observed in Mrp2-deficient rats. Under these conditions, genipin treatment increased the protein mass of Mrp2 in the CMVs but not the mRNA level. In immunoelectron microscopic studies, a marked increase in Mrp2 density in the canalicular membrane (CM) and microvilli was observed in the genipin-treated liver tissue sections when compared with the vehicle-treated liver tissue sections. In conclusion, genipin may enhance the bile acid-independent secretory capacity of hepatocytes, mainly by stimulation of exocytosis and insertion of Mrp2 in the bile canaliculi. ICKT may be a potent therapeutic agent for a number of cholestatic liver diseases.
authors.affiliation: Department of Gastroenterology, Institute of Clinical Medicine, The University of Tsukuba, Ibaraki, Japan. shodaj@md.tsukuba.ac.jp
authors.forename: Junichi
authors.initials: J
authors.lastname: Shoda
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Miura
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Utsunomiya
authors.forename: Koji
authors.initials: K
authors.lastname: Oda
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Masahito
authors.initials: M
authors.lastname: Kano
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ikegami
authors.forename: Naomi
authors.initials: N
authors.lastname: Tanaka
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Akita
authors.forename: Kousei
authors.initials: K
authors.lastname: Ito
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Suzuki
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Sugiyama
mesh_terms: D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D008841:Actin Cytoskeleton / Q000187:drug effects; D000255:Adenosine Triphosphate / Q000378:metabolism; D000284:Administration, Oral; D000818:Animals; D000838:Anions / Q000378:metabolism; D001646:Bile / Q000378:metabolism*; D002756:Cholagogues and Choleretics / Q000737:chemistry / Q000494:pharmacology*; D004365:Drugs, Chinese Herbal / Q000494:pharmacology; D004958:Estradiol / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D015870:Gene Expression; D066298:In Vitro Techniques; D057889:Iridoid Glycosides; D039823:Iridoids / Q000494:pharmacology; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism*; D010590:Phalloidine / Q000494:pharmacology; D011714:Pyrans / Q000737:chemistry / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D014316:Tritium
chemical_list: D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters; D000255:Adenosine Triphosphate; D000838:Anions; D002756:Cholagogues and Choleretics; D004365:Drugs, Chinese Herbal; D004958:Estradiol; D057889:Iridoid Glycosides; D039823:Iridoids; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D010590:Phalloidine; D011714:Pyrans; D012333:RNA, Messenger; D014316:Tritium; C490548:Abcb11 protein, rat; C078038:inchinko-to; C007835:geniposide; C025483:estradiol-17 beta-glucuronide; C007834:genipin