Disruption of function and localization of tight-junctional structures and Mrp2 in sustained estradiol-17ß-D-glucuronide-induced cholestasis

MOTTINO, ALDO D; HOFFMAN, TIM; CROCENZI, FERNANDO A; SANCHEZ POZZI, EJ; ROMA, MARCELO G; VORE, MARY

AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY

AMER PHYSIOLOGICAL SOC

Año: 2007 vol. 293 p. 391 - 402

0193-1857

Estradiol-17-D-glucuronide (E217G) induces immediate, profound but transient cholestasis in rats when administered as a single bolus dose. Here we examined the consequence of sustained E217G cholestasis and assessed function and localization of the tight-junctional proteins zonnula occludens-1 (ZO-1) and occludin, and of the canalicular transporter Mrp2. An initial dose of E217G (15 µmol/kg, i.v.), followed by 5 subsequent doses of 7.5 µmol/kg from 60 to 240 min induced a sustained 40 - 70% decrease in bile flow. Following their biliary retrograde administration, cholera toxin B subunit-FITC or horseradish peroxidase were detected at the sinusoidal domain, indicating opening of the paracellular route; this occurred as early as 15 min after the first dose, as well as 15 min after the last dose of E217G, but not following administration of vehicle in controls. Localization of ZO-1 and occludin was only slightly affected under acute cholestatic conditions, but was severely disrupted under sustained cholestasis, with their appearance suggesting a fragmented structure. Endocytic internalization of Mrp2 to the pericanalicular region was apparent 20 min after single E217G-administration; however, Mrp2 was found more deeply internalized and partially redistributed to the basolateral membrane under sustained cholestasis. In conclusion, acute E217G-induced cholestasis increased permeability of the tight junction, while sustained cholestasis provoked a significant redistribution of ZO-1, occludin and Mrp2 in addition to increased permeability of the tight-junction. Altered tight junction integrity likely contributes to impaired bile secretion, and may be causally related to changes in Mrp2 localization.