title: Regulation of expression and activity of rat intestinal multidrug resistance-associated protein 2 by cholestatic estrogens.
abstract: The effect of the cholestatic estrogens ethynylestradiol (EE) and estradiol 17beta-D-glucuronide (E2-17G) on expression and activity of intestinal multidrug resistant-associated protein 2 (Mrp2, Abcc2) was studied in rats. Expression and localization of Mrp2 were evaluated by Western blotting, real-time polymerase chain reaction, and confocal immunofluorescence microscopy. Mrp2 transport activity toward dinitrophenyl-S-glutathione (DNP-SG) was assessed in vitro in intestinal sacs. EE, administered subcutaneously at a 5 mg/kg b.wt. dose, for 5 consecutive days, produced a marked decrease in Mrp2 expression at post-transcriptional level, without affecting its normal localization at the apical membrane of the enterocyte. This effect was selective because expression of other ATP-binding cassette proteins such as breast cancer resistance protein and Mrp3 were not affected and that of multidrug resistance protein 1 was only minimally impaired. Consistent with down-regulation of expression of Mrp2, a significant impairment in serosal to mucosal transport of DNP-SG and in protection against absorption of this same compound were registered. Simultaneous administration of EE with spironolactone (200 micromol/kg b.wt./day for 3 days), an Mrp2 inducer, prevented these alterations, confirming down-regulation of expression of Mrp2 by EE as a major component of functional changes. Incorporation of E2-17G (30 microM) in the serosal medium of intestinal sacs decreased serosal to mucosal transport of DNP-SG, probably because of competitive inhibition, without affecting normal Mrp2 expression or localization. Our data indicate impairment of function of intestinal Mrp2 by both cholestatic estrogens, although through a different mechanism. This finding represents an aggravation of deteriorated hepatic Mrp2 function that could further increase bioavailability of specific xenobiotics after oral exposure.
authors.affiliation: Instituto de Fisiología Experimental, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina.
authors.forename: Agostina
authors.initials: A
authors.lastname: Arias
authors.forename: Silvina S M
authors.initials: SS
authors.lastname: Villanueva
authors.forename: María L
authors.initials: ML
authors.lastname: Ruiz
authors.forename: Marcelo G
authors.initials: MG
authors.lastname: Luquita
authors.forename: Luis M
authors.initials: LM
authors.lastname: Veggi
authors.forename: José M
authors.initials: JM
authors.lastname: Pellegrino
authors.forename: Mary
authors.initials: M
authors.lastname: Vore
authors.forename: Viviana A
authors.initials: VA
authors.lastname: Catania
authors.forename: Aldo D
authors.initials: AD
authors.lastname: Mottino
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D002779:Cholestasis / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects*; D007413:Intestinal Mucosa / Q000378:metabolism; D008297:Male; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
chemical_list: D018528:ATP-Binding Cassette Transporters; D015415:Biomarkers; D004958:Estradiol; D004967:Estrogens; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C423013:Abcc2 protein, rat; C025483:estradiol-17 beta-glucuronide