Down-Regulation of Hepatic Transporters for BSP in Rats with Indomethacin-Induced Intestinal Injury

Abstract

Systemic administration of indomethacin (IDM) causes inflammation of the small intestine. Although the pathogenic events of IDM are more complex, it is considered that suppression of prostaglandin synthesis, mitochondrial damage and oxidative stress response are involved in it.1,2) And, generation of reactive oxygen species decreases alkaline phosphatase (ALP) activity in intestinal mucosa, followed by an attenuation of differentiation and proliferation of villus. 3,4) In addition, gram-negative bacteria-derived endotoxin also strongly induces damages of villus enterocyte and contributes to its exacerbation. 5,6) Previous studies using animal models of bowel disease involving IDM-induced intestinal injury, trinitrobenzene sulfonic acid (TNBS)-induced colitis and dextran sulfate sodium-induced colitis have shown that the enteropathy is associated with the alteration of hepatic cytochrome P450 (CYP) and been suggested the relationship of the entering bacterial endotoxin into portal vein according to an increase of intestinal epithelium permeability. [7][8][9] In contrast with CYPs, little is known about the expression of hepatic transporters in bowel injury, although drug transporters as well as metabolizing enzymes play an important role in the disposition of most drugs.Organic anion transporting polypeptides (Oatp), located in the liver sinusoidal membrane, take part in the hepatic uptake of bile acids, peptide hormones, steroid hormones and a variety of drugs.10,11) Multidrug resistance-associated protein 2 (Mrp2), located in the liver canalicular membrane, excretes a variety of organic anions including endogenous glutathione (GSH), GSH-conjugates and glucuronides into bile. 12,13) Interplay between these influx and efflux transporters is fundamental to the biliary elimination or enterohepatic recirculation of endogenous and exogenous compounds. [14][15][16] The aim of this study is to characterize the alteration in these hepatic organic anion transporters in rats with IDM-induced injury to the small intestine. The hepatic transporter function was evaluated by a pharmacokinetic study of bromosulfophthalein (BSP), and the expression of hepatic transporters for BSP was also evaluated in control and IDMtreated rats. Inflammatory mediators in the portal plasma were traced as causal candidates ultimately affecting hepatic transporter expression. MATERIALS AND METHODSChemicals IDM was purchased from Wako Pure Chemical Industries (Osaka, Japan). BSP was purchased from Sigma-Aldrich (St. Louis, MO, U.S.A.). Other chemicals and solvents used were of the highest quality commercially available.In Vivo Experimental Procedures Male Sprague-Dawley rats (Japan SLC Inc., Shizuoka, Japan) weighing 235-290 g (7-8 weeks old) were used throughout the experiments. Rats were housed in an air-conditioned room (25°C) under a 12 h light-dark cycle for at least 1 week before use. Food (the MF diet, standard laboratory diet commercially available, Oriental Yeast Co., Ltd., Tokyo, Japan) and water were given ad libitum. The rats were inje...

Integrated Approach of In Vivo and In Vitro Evaluation of the Involvement of Hepatic Uptake Organic Anion Transporters in the Drug Disposition in Rats Using Rifampicin as an Inhibitor

“…Considering BSP is mainly cleared by hepatic transporters with minimal contribution from Cyp enzyme (Fujiyama et al, 2007), this observation can be accounted for by the inhibition of hepatic uptake transporters, presumably Oatps. This is supported by the observation that the average plasma concentration of rifampicin (from 1-7 hours) achieved after an oral dose of 30 mg/kg was 31.4 mM, which is high enough to inhibit Oatps considering the IC 50 value of rifampicin for rat Oatps (3.2 mM) (Zaher et al, 2008) and the unbound fraction in plasma (0.25) (unpublished data).…”

Long-Lasting Inhibition of the Transporter-Mediated Hepatic Uptake of Sulfobromophthalein by Cyclosporin A in Rats

“…For example, administration of indomethacin caused intestinal injury, leading to down-regulation of mRNA and protein of hepatic Oatp1b2 and Mrp2 in rats, and ethynylestradiol reduced the expression of Na ϩ -taurocholate cotransporting polypeptide, bile salt export pump, and Mrp2 (Lee et al, 2000;Fujiyama et al, 2007). By this mechanism, drugs can cause transporter dysfunction.…”

Regulation of hepatic ABCC transporters by xenobiotics and in disease states

“…; 3 days), liver Mrp2 mRNA and protein expression is significantly reduced. This is caused by nitric oxide arising from bowel injury (Fujiyama et al, 2007). …”