Advertisement
Research ArticleArticle

EXPRESSION PROFILES OF DRUG-METABOLIZING ENZYME CYP3A AND DRUG EFFLUX TRANSPORTER MULTIDRUG RESISTANCE 1 SUBFAMILY mRNAS IN RAT SMALL INTESTINE

Kohji Takara, Noriaki Ohnishi, Sayo Horibe and Teruyoshi Yokoyama
Drug Metabolism and Disposition October 2003, 31 (10) 1235-1239; DOI: https://doi.org/10.1124/dmd.31.10.1235

Abstract

The purpose of this study is to examine the expression profiles of CYP3A1, CYP3A2, CYP3A9, and CYP3A18 mRNAs as well as multidrug resistance (mdr)1a and mdr1b mRNAs in the liver and small intestine of normal male Wistar rats using a reverse transcription-polymerase chain reaction (PCR). In the rat liver, the PCR products for CYP3A1, CYP3A2, and CYP3A18 were readily detectable, whereas CYP3A9 was slightly and mdr1a and mdr1b barely detected. Surprisingly, no PCR products for CYP3A1 and CYP3A2 were detected in the small intestine, but those for CYP3A9, CYP3A18, and mdr1a were readily detectable, and a faint band for mdr1b was also observed. Both CYP3A9 and CYP3A18 levels were found to be high in the duodenum and decreased from the top to bottom of the gut, indicating regional differences in both CYP3A9 and CYP3A18 expression in the small intestine. In contrast, mdr1a expression increased gradually from the upper to lower intestine. Consequently, it was suggested that drug metabolism in the small intestine of normal rats was mediated by CYP3A9 and CYP3A18 rather than CYP3A1 and CYP3A2. Also, regional differences of CYP3A9, CYP3A18, and mdr1a expression were found in the small intestine. The distributions of CYP3A9 and CYP3A18 were different from the distribution of mdr1a, suggesting the cooperative action of drug clearance pathways. This information is important to drug metabolism research based on ex vivo and in vivo studies using rats.

The cytochrome P450 (P4501)-dependent microsomal mono-oxygenase system consists of a flavoprotein, cytochrome P450 reductase, and a multigene superfamily of hemeproteins (the cytochromes P450). Cytochromes P450 belonging to the CYP3A subfamily are among the most abundant, being predominantly expressed in the liver, but are also present in the gut, leukocytes, and brain (Miksys and Tyndale, 2002; Ding and Kaminsky, 2003). In addition, these CYP3A enzymes catalyze the 6β-hydroxylation of steroids such as cortisol, testosterone, and estradiol and are responsible for the metabolism of numerous drugs, including psychotropic, cardiac, analgesic, hormonal, immunosuppressant, antibiotic, and anticancer drugs. Thus, the CYP3A subfamily plays an important role in the detoxification of endogenous substances and xenobiotics.

In the rat, four CYP3A cDNAs have been recently characterized: CYP3A1 [also referred to as CYP3A23 (Kirita and Matsubara, 1993; Komori and Oda, 1994)], CYP3A2, CYP3A9, and CYP3A18. CYP3A1 had been identified in the liver after the treatment of male rats with a synthetic steroid, pregnenolone 16α-carbonitrile (Gonzalez et al., 1985). CYP3A2 is expressed in the livers of both female and male neonatal rats, but levels drop below detectable limits at puberty in females, whereas they are preserved throughout life in males (Gonzalez et al., 1986). CYP3A9 is the most recently cloned member of the family, and its mRNA was detected only in adult rats, with a higher level of expression in females (Wang et al., 1996; Mahnke et al., 1997). CYP3A18 is expressed predominantly in males (Strotkamp et al., 1995; Nagata et al., 1996). However, their existence in rat small intestine has been reported using various types of experimental methods, whereas some have reported the CYP3A subfamily was not expressed in rat small intestine (Watkins et al., 1987; de Waziers et al., 1990; Kolars et al., 1992; Zhang et al., 1996; Chiba et al., 1997). Since various types of reports exist, an understanding of their expression profiles is very important to drug metabolism research based on ex vivo and in vivo studies using rats.

It has been demonstrated that the substrate specificity of CYP3A4 in humans overlapped with that of the MDR1 gene (mdr1a and mdr1b in rat) product, the multidrug efflux transporter P-glycoprotein. It is now well accepted that P-glycoprotein is expressed in normal tissues with excretory function, i.e., intestine, liver, kidney, etc., and P-glycoprotein expressed throughout the body plays an important role in the pharmacokinetics of drugs that are substrates for P-glycoprotein (Fromm, 2002; Lin, 2003). Therefore, the impact of P-glycoprotein on pharmacokinetics as well as CYP3A4 has increased, and its expression profiles are also important.

In this study, the expression profiles of CYP3A1, CYP3A2, CYP3A9, and CYP3A18 mRNAs as well as mdr1a and mdr1b mRNAs were examined in both the liver and small intestine of normal male Wistar rats using a reverse transcription-polymerase chain reaction (RT-PCR).

Materials and Methods

Animals. Nine-week-old male Wistar rats (240–250 g) were purchased from Japan SLC, Inc. (Hamamatsu, Japan). After an overnight fast with free access to water, rats were anesthetized by intraperitoneal injection of pentobarbital sodium (Nembutal injection; Dainippon Pharmaceutical Co., Ltd., Osaka, Japan), and sacrificed by exsanguination via the aorta in the abdomen. Animal experiments were carried out in accordance with the Guidelines for Animal Experimentation at Kyoto Pharmaceutical University.

RNA Extraction. The liver was excised quickly after exsanguination, and parts (3-mm squares) were cut out. In the case of the small intestine, it was excised quickly after exsanguination and rinsed in ice-cold 0.9% NaCl solution. The small intestine (total of ca. 90 cm) was divided into three parts: upper (almost corresponding to the duodenum, ∼30 cm immediately distal to the pyloric valve), middle (almost corresponding to the jejunum, the 30 cm between the upper and lower sites), and lower (almost corresponding to the ileum, the last 30 cm before the cecum). Each part was re-divided into three (about 10 cm each), and the centers (1 cm distal) were cut out to obtain nine segments. These were designated as S1, S2, S3, S4, S5, S6, S7, S8, and S9, in the direction from the duodenum to ileum. Tissue samples of both liver and small intestine were collected from three rats, immersed quickly into RNAlater solution (Sigma-Aldrich, St. Louis, MO), and stored at -80°C until the RNA extraction.

For the extraction of RNA, first the aliquots (3-mm squares) of tissue samples were homogenized in RNAlater solution using a pestle, then their total RNA was extracted using a GenElute Mammalian Total RNA kit (Sigma-Aldrich) according to previous reports (Takara et al., 2002, 2003a,b) with modifications.

RT-PCR. RT-PCR analysis was performed according to modifications described in previous reports (Takara et al., 2002, 2003a,b). Aliquots (0.3 μg) of total RNA were used for reverse transcription with an RNA PCR kit (AMV) ver. 2.1 (Takara Shuzo Co., Ltd., Shiga, Japan). The RT reaction was conducted in 15 μl of RT reaction mixture, and this was incubated at 30°C for 10 min and subsequently at 42°C for 30 min in a thermal cycler (iCycler Thermal Cycler; Bio-Rad, Hercules, CA). The RT reaction was terminated by heating at 99°C for 5 min, followed by cooling at 5°C for 5 min in a thermal cycler (Bio-Rad), giving the RT product.

PCR primer sequences for amplification of CYP3A and the mdr1 subfamily, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) are listed in Table 1 (Vos et al., 1998; Hoen et al., 2000; Yokogawa et al., 2002) and were synthesized by Proligo K. K. Japan (Kyoto, Japan). PCR amplification of cDNA was performed in a total reaction volume of 25 μl including 5 μl of RT product using an RNA PCR kit (AMV) ver. 2.1 (Takara Shuzo Co., Ltd.). PCR amplification was initiated by one cycle of 95°C for 1 min followed by 22 (for CYP3A9 and GAPDH), 28 (for CYP3A1, CYP3A2, and CYP3A18), and 30 (for mdr1a and mdr1b) sequential cycles of denaturation at 94°C for 30 s, annealing at 60°C for 1 min, and extension at 72°C for 1 min, and then one cycle of final extension at 72°C for 10 min in a thermal cycler (Bio-Rad), giving the PCR product. Products were separated on Tris-acetate/EDTA 3% agarose gels containing 100 ng/ml ethidium bromide and photographed under ultraviolet illumination at 312 nm with a Polaroid camera (Eastman Kodak Co., Rochester, NY). Band densities were measured using the computer program NIH Image ver. 1.62 (National Institutes of Health, Bethesda, MD), and the ratio of band density (target gene/GAPDH) was calculated.

View this table:
TABLE 1

Gene-specific oligonucleotide PCR primers

Statistical Analysis. Results are expressed as percentages of the ratio of target gene to GAPDH mRNA levels in the S1 group. These data except the liver were compared with the S1 region by nonrepeated measures one-way analysis of variance followed by Dunnett's test. The p values of less than 0.05 (two-tailed) were considered significant.

Results

Expression Profiles of CYP3A and mdr1 Subfamily mRNAs in Rat Liver and Small Intestine. The mRNA expression profiles of CYP3A and the mdr1 subfamily were compared in the liver and small intestine (Fig. 1). In normal rat liver, the PCR products for CYP3A1, CYP3A2, and CYP3A18 were readily detectable, whereas little CYP3A9 mRNA was detected (Fig. 1A). In addition, faint bands were obtained for mdr1a and mdr1b mRNAs. Surprisingly, no PCR products for CYP3A1 and CYP3A2 mRNAs in the small intestine of normal rats were detected (Fig. 1B). In contrast, the PCR products for CYP3A9, CYP3A18, and mdr1a mRNAs were readily detectable, and a faint band for mdr1b was also observed.

Fig. 1.
Fig. 1.

Expression profiles for CYP3A and mdr1 subfamily mRNAs in rat liver (A) and small intestine (B) by RT-PCR.

Rats were sacrificed, and their tissues were quickly collected into RNAlater solution (Sigma-Aldrich). Total RNA was extracted from the tissue using a GenElute Mammalian Total RNA kit (Sigma-Aldrich). PCR products were separated on a 3% agarose gel stained with 100 ng/ml ethidium bromide to visualize the DNA bands. M.W., molecular weight marker (ϕX174-HaeIII digest).

Regional Differences in CYP3A9 mRNA Expression in Rat Small Intestine. The CYP3A9 mRNA expression increased in the direction from the upper to lower intestine of normal rats, was significantly stronger in the S3 than in the S1 region, and subsequently declined in the S4 region (Fig. 2). The expression from S5 to S9 was almost stable, and not significantly different from that in the S1 region. These levels were similar to those of CYP3A9 in normal liver, compared on a per 0.3-μg total RNA basis.

Fig. 2.
Fig. 2.

Regional differences in CYP3A9 mRNA expression in rat small intestine determined by RT-PCR.

Rats were sacrificed, and their tissues were quickly collected into RNAlater solution (Sigma-Aldrich). Total RNA was extracted from the tissue using a GenElute Mammalian Total RNA kit (Sigma-Aldrich). PCR products were separated on a 3% agarose gel stained with 100 ng/ml ethidium bromide to visualize the DNA bands. Data were obtained after densitometric analysis of three electrophoretograms derived from three rats. Results are expressed as percentages of the ratio of CYP3A9 to GAPDH mRNA levels in the S1 group. Each bar represents the mean ± S.E. of three rats. *, p < 0.05, significantly different from S1.

Regional Differences in CYP3A18 mRNA Expression in Rat Small Intestine. The CYP3A18 mRNA expression increased in the direction from the upper to lower intestine of normal rats (Fig. 3). The expression in S3 was maximal and significantly higher than that in S1, and the expression in the region from S4 to S9 was almost stable. In addition, CYP3A18 mRNA expression throughout the small intestine was remarkably weaker than that in liver, compared on a per 0.3-μg total RNA basis.

Fig. 3.
Fig. 3.

Regional differences in CYP3A18 mRNA expression in rat small intestine determined by RT-PCR.

Rats were sacrificed, and their tissues were quickly collected into RNAlater solution (Sigma-Aldrich). Total RNA was extracted from the tissue using a GenElute Mammalian Total RNA kit (Sigma-Aldrich). PCR products were separated on a 3% agarose gel stained with 100 ng/ml ethidium bromide to visualize the DNA bands. Data were obtained after densitometric analysis of three electrophoretograms derived from three rats. Results are expressed as percentages of the ratio of CYP3A18 to GAPDH mRNA levels in the S1 group. Each bar represents the mean ± S.E. of three rats. *, p < 0.05 significantly different from S1.

Regional Differences in mdr1a mRNA Expression in Rat Small Intestine. From the upper to lower intestine, the mdr1a mRNA expression in normal rats gradually increased (Fig. 4), with the expression in the lower region markedly stronger than that in the upper or middle region. Moreover, the mdr1a mRNA expression level was higher in the small intestine, especially the lower region, than liver, compared on a per 0.3-μg total RNA basis.

Fig. 4.
Fig. 4.

Regional differences in mdr1a mRNA expression in rat small intestine determined by RT-PCR.

Rats were sacrificed, and their tissues were quickly collected into RNAlater solution (Sigma-Aldrich). Total RNA was extracted from the tissue using a GenElute Mammalian Total RNA kit (Sigma-Aldrich). PCR products were separated on a 3% agarose gel stained with 100 ng/ml ethidium bromide to visualize the DNA bands. Data were obtained after densitometric analysis of three electrophoretograms derived from three rats. Results are expressed as percentages of the ratio of mdr1a to GAPDH mRNA levels in the S1 group. Each bar represents the mean ± S.E. of three rats. * and **, p < 0.05 and 0.01, significantly different from S1, respectively.

Discussion

Consistent with previous reports (Mahnke et al., 1997; Rowlands et al., 2000), the expression of CYP3A1, CYP3A2, CYP3A9, and CYP3A18 mRNAs was observed in the liver of normal male rats (Fig. 1A). Unexpectedly, no signals for CYP3A1 and CYP3A2 were detected in the small intestine of normal rats, but CYP3A9 and CYP3A18 mRNA were observed (Fig. 1B). To rule out inhibition of the PCR caused by the primer interaction, other primer pairs, reported by Zhang et al. (1996) and Yokogawa et al. (2002), were used. However, their signals were also unable to be detected, even using the samples derived from different sites of the normal small intestine (data not shown). Is CYP3A1 or CYP3A2 really present in the small intestine of normal Wistar rats? The presence of the CYP3A subfamily in rat small intestine has been reported (Watkins et al., 1987; de Waziers et al., 1990; Chiba et al., 1997), although some authors were unable to detect message for CYP3A1 or CYP3A2 (Zhang et al., 1996; Gushchin et al., 1999). Also, it was reported that a protein in enterocytes of male Wistar rats reacted with a commercially available antibody to CYP3A2, but RT-PCR analysis resulted in the amplification of a product, which corresponded to CYP3A1 and not to CYP3A2 (Kolars et al., 1992). Taking these reports into consideration, CYP3A1, but not CYP3A2, is considered to be expressed in rat small intestine. However, Kolars et al. (1992) have reported that the message for CYP3A1 was able to be detected by RT-PCR in the small intestine of dexamethasone-treated rats, but not detected in normal rats. Furthermore, Zhang et al. (1996) obtained data on whether CYP3A1 was expressed or not in the small intestine, but the expression level was not entirely clarified. Therefore, a moot point remains regarding the expression of CYP3A1 in the small intestine of normal rats. Gushchin et al. (1999) reported the presence of a CYP3A isoenzyme, which is clearly distinguishable from CYP3A1 and CYP3A2, in rat intestinal microsomes using immunoblot, RT-PCR, and Northern blot analysis. In the present study, we were unable to detect the message for either CYP3A1 or CYP3A2 in the small intestine of normal rats using RT-PCR (Fig. 1). Accordingly, CYP3A2 has been confirmed not to be expressed in the small intestine of normal male rats. It was, however, suggested that CYP3A1 expression was absent or extremely weak in the small intestine of normal male rats considering previous reports.

Of note, CYP3A9 was observed in the small intestine of normal male rats, and its level was higher in the small intestine than in the liver, although not significantly (Figs. 1 and 2), confirming the results of Robertson et al. (1998) and Gushchin et al. (1999). In addition, CYP3A18 was remarkably expressed in both liver and small intestine of normal male rats (Figs. 1 and 3). The previous reports also indicated that CYP3A18 was expressed predominantly in the liver rather than in the small intestine in normal male Wistar rats, but the hepatic expression of CYP3A18 was of much higher levels in male than in female rats (Robertson et al., 1998). Hence, it was found that CYP3A9 and CYP3A18, but not CYP3A1 and CYP3A2, were predominantly expressed in the small intestine of normal male Wistar rats. The expression of both CYP3A9 and CYP3A18 was, however, reported to be remarkably dependent on sex (Robertson et al., 1998). Accordingly, it was suggested that CYP3A9 and CYP3A18 play a major role in drug metabolism in the gut via the CYP3A subfamily, but may be gender-dependent. Therefore, we propose the importance of considering the drug metabolism mediated by CYP3A9 and CYP3A18 rather than CYP3A1 and CYP3A2 in the small intestine of normal male rats.

Next, we examined whether there were regional differences in CYP3A9 or CYP3A18 expression in the small intestine of normal Wistar rats. Both CYP3A9 and CYP3A18 were found to be highly expressed in the upper site (almost corresponding to the duodenum) of the small intestine (Figs. 2 and 3). It is generally accepted that the level of P450s decreases in the direction from top to bottom of the gut (Kaminsky and Fasco, 1991), supporting the present findings. Therefore, it was found that there were regional differences in both CYP3A9 and CYP3A18 expression in the small intestine of normal rats, indicating the need for performing experiments carefully.

Expression profiles of mdr1a and mdr1b as well as the CYP3A subfamily were also examined. Signals for mdr1a and mdr1b were detected in both liver and small intestine of normal male rats, and the expression of mdr1a in small intestine was remarkable (Fig. 1) and consistent with a previous report (Borst et al., 1993). In addition, the level of mdr1a mRNA in rat small intestine increased significantly from the top to bottom of the gut (Fig. 4). Stephens et al. (2002) also found that the level of P-glycoprotein was higher in ileum than jejunum by immunoblotting, although in normal mice. Furthermore, the level of mdr1a was higher in small intestine than in liver (Figs. 1 and 4), indicating the importance of P-glycoprotein in the intestine, as others have claimed. Accordingly, it was found that regional differences in the expression of mdr1a mRNA as well as CYP3A9 and CYP3A18 existed in the small intestine of normal male rats. Also, the trends for distribution were markedly different between CYP3A and mdr1a, implying cooperative action of the CYP3A family and P-glycoprotein in the drug clearance pathway (as stated below).

Regrettably, the physiological rationale of our findings remains unclear, but we speculate as follows. The jejunum has a relatively short transit time (∼40 min in the rat) (Kayne et al., 1993); in other words, the high membrane permeability in the jejunum is essential for the absorption of lipophilic xenobiotics. In the case of such substances, P-glycoprotein-mediated efflux might be offset by passive influx and consequently lead to a net absorption. Thus, P450s are considered essential for the detoxification of xenobiotics, which have penetrated the intestinal epithelial cells. In contrast, the transit time in the ileum was reported to be considerably longer (∼140 min in the rat) (Kayne et al., 1993), and thus absorption was able to be performed even at a lower membrane permeability. Given that the membrane permeability is low, P-glycoprotein-mediated efflux but not P450-mediated metabolism is considered to be very efficient for the detoxification of xenobiotics. Therefore, these points are considered to be an interpretation of the high levels of expression of CYP3A9 and CYP3A18 at the upper site and mdr1a at the lower site in rat small intestine.

In conclusion, we clarified the expression profiles of CYP3A and mdr1 subfamily mRNAs in both liver and small intestine of normal male Wistar rats and also the regional differences of CYP3A9, CYP3A18, and mdr1a in the small intestine. The information is very important to drug metabolism research based on ex vivo and in vivo studies using rats.

Footnotes

  • ↵1 Abbreviations used are: P450, cytochrome P450; RT-PCR, reverse transcription-polymerase chain reaction; GAPDH, glyceraldehyde-3-phosphate dehydrogenase.

    • Received March 17, 2003.
    • Accepted July 1, 2003.

References

  1. ↵
    Borst P, Schinkel AH, Smit JJ, Wagenaar E, Van Deemter L, Smith AJ, Eijdems EW, Baas F, and Zaman GJ (1993) Classical and novel forms of multidrug resistance and the physiological functions of P-glycoproteins in mammals. Pharmacol Ther 60: 289-299.
    OpenUrlCrossRefPubMed
  2. ↵
    Chiba M, Hensleigh M, and Lin JH (1997) Hepatic and intestinal metabolism of indinavir, an HIV protease inhibitor, in rat and human microsomes. Major role of CYP3A. Biochem Pharmacol 53: 1187-1195.
    OpenUrlCrossRefPubMed
  3. ↵
    de Waziers I, Cugnenc PH, Yang CS, Leroux JP, and Beaune PH (1990) Cytochrome P 450 isoenzymes, epoxide hydrolase and glutathione transferases in rat and human hepatic and extrahepatic tissues. J Pharmacol Exp Ther 253: 387-394.
    OpenUrlAbstract/FREE Full Text
  4. ↵
    Ding X and Kaminsky LS (2003) Human extrahepatic cytochromes P450: function in xenobiotic metabolism and tissue-selective chemical toxicity in the respiratory and gastrointestinal tracts. Annu Rev Pharmacol Toxicol 43: 149-173.
    OpenUrlCrossRefPubMed
  5. ↵
    Fromm MF (2002) The influence of MDR1 polymorphisms on P-glycoprotein expression and function in humans. Adv Drug Deliv Rev 54: 1295-1310.
    OpenUrlCrossRefPubMed
  6. ↵
    Gonzalez FJ, Nebert DW, Hardwick JP, and Kasper CB (1985) Complete cDNA and protein sequence of a pregnenolone 16 α-carbonitrile-induced cytochrome P-450. A representative of a new gene family. J Biol Chem 260: 7435-7441.
    OpenUrlAbstract/FREE Full Text
  7. ↵
    Gonzalez FJ, Song BJ, and Hardwick JP (1986) Pregnenolone 16 α-carbonitrile-inducible P-450 gene family: gene conversion and differential regulation. Mol Cell Biol 6: 2969-2976.
    OpenUrlAbstract/FREE Full Text
  8. ↵
    Gushchin GV, Gushchin MI, Gerber N, and Boyd RT (1999) A novel cytochrome P450 3A isoenzyme in rat intestinal microsomes. Biochem Biophys Res Commun 255: 394-398.
    OpenUrlCrossRefPubMed
  9. ↵
    Hoen PA, Commandeur JN, Vermeulen NP, Van Berkel TJ, and Bijsterbosch MK (2000) Selective induction of cytochrome P450 3A1 by dexamethasone in cultured rat hepatocytes: analysis with a novel reverse transcriptase-polymerase chain reaction assay section sign. Biochem Pharmacol 60: 1509-1518.
    OpenUrlCrossRefPubMed
  10. ↵
    Kaminsky LS and Fasco MJ (1991) Small intestinal cytochromes P450. Crit Rev Toxicol 21: 407-422.
    OpenUrlPubMed
  11. ↵
    Kayne LH, D'Argenio DZ, Meyer JH, Hu MS, Jamgotchian N, and Lee DB (1993) Analysis of segmental phosphate absorption in intact rats. A compartmental analysis approach. J Clin Investig 91: 915-922.
    OpenUrlCrossRefPubMed
  12. ↵
    Kirita S and Matsubara T (1993) cDNA cloning and characterization of a novel member of steroid-induced cytochrome P450 3A in rats. Arch Biochem Biophys 307: 253-258.
    OpenUrlCrossRefPubMed
  13. ↵
    Kolars JC, Schmiedlin-Ren P, Dobbins WO 3rd, Schuetz J, Wrighton SA, and Watkins PB (1992) Heterogeneity of cytochrome P450IIIA expression in rat gut epithelia. Gastroenterology 102: 1186-1198.
    OpenUrlPubMed
  14. ↵
    Komori M and Oda Y (1994) A major glucocorticoid-inducible P450 in rat liver is not P450 3A1. J Biochem (Tokyo) 116: 114-120.
    OpenUrlAbstract/FREE Full Text
  15. ↵
    Lin JH (2003) Drug-drug interaction mediated by inhibition and induction of P-glycoprotein. Adv Drug Deliv Rev 55: 53-81.
    OpenUrlCrossRefPubMed
  16. ↵
    Mahnke A, Strotkamp D, Roos PH, Hanstein WG, Chabot GG, and Nef P (1997) Expression and inducibility of cytochrome P450 3A9 (CYP3A9) and other members of the CYP3A subfamily in rat liver. Arch Biochem Biophys 337: 62-68.
    OpenUrlCrossRefPubMed
  17. ↵
    Miksys SL and Tyndale RF (2002) Drug-metabolizing cytochrome P450s in the brain. J Psychiatry Neurosci 27: 406-415.
    OpenUrlPubMed
  18. ↵
    Nagata K, Murayama N, Miyata M, Shimada M, Urahashi A, Yamazoe Y, and Kato R (1996) Isolation and characterization of a new rat P450 (CYP3A18) cDNA encoding P450(6)β-2 catalyzing testosterone 6 β- and 16 α-hydroxylations. Pharmacogenetics 6: 103-111.
    OpenUrlCrossRefPubMed
  19. ↵
    Robertson GR, Farrell GC, and Liddle C (1998) Sexually dimorphic expression of rat CYP3A9 and CYP3A18 genes is regulated by growth hormone. Biochem Biophys Res Commun 242: 57-60.
    OpenUrlCrossRefPubMed
  20. ↵
    Rowlands JC, Wang H, Hakkak R, Ronis MJ, Strobel HW, and Badger TM (2000) Chronic intragastric infusion of ethanol-containing diets induces CYP3A9 while decreasing CYP3A2 in male rats. J Pharmacol Exp Ther 295: 747-752.
    OpenUrlAbstract/FREE Full Text
  21. ↵
    Stephens RH, Tanianis-Hughes J, Higgs NB, Humphrey M, and Warhurst G (2002) Region-dependent modulation of intestinal permeability by drug efflux transporters: in vitro studies in mdr1a(-/-) mouse intestine. J Pharmacol Exp Ther 303: 1095-1101.
    OpenUrlAbstract/FREE Full Text
  22. ↵
    Strotkamp D, Roos PH, and Hanstein WG (1995) A novel CYP3 gene from female rats. Biochim Biophys Acta 1260: 341-344.
    OpenUrlPubMed
  23. ↵
    Takara K, Tsujimoto M, Kokufu M, Ohnishi N, and Yokoyama T (2003a) Up-regulation of MDR1 function and expression by cisplatin in LLC-PK1 cells. Biol Pharm Bull 26: 205-209.
    OpenUrlCrossRefPubMed
  24. ↵
    Takara K, Tsujimoto M, Ohnishi N, and Yokoyama T (2002) Digoxin up-regulates MDR1 in human colon carcinoma Caco-2 cells. Biochem Biophys Res Commun 292: 190-194.
    OpenUrlCrossRefPubMed
  25. ↵
    Takara K, Tsujimoto M, Ohnishi N, and Yokoyama T (2003b) Effects of continuous exposure to digoxin on MDR1 function and expression in Caco-2 cells. J Pharm Pharmacol 55: 675-681.
    OpenUrlCrossRefPubMed
  26. ↵
    Vos TA, Hooiveld GJ, Koning H, Childs S, Meijer DK, Moshage H, Jansen PL, and Muller M (1998) Up-regulation of the multidrug resistance genes, Mrp1 and Mdr1b, and downregulation of the organic anion transporter, Mrp2 and the bile salt transporter, Spgp, in endotoxemic rat liver. Hepatology 28: 1637-1644.
    OpenUrlCrossRefPubMed
  27. ↵
    Wang H, Kawashima H, and Strobel HW (1996) cDNA cloning of a novel CYP3A from rat brain. Biochem Biophys Res Commun 221: 157-162.
    OpenUrlCrossRefPubMed
  28. ↵
    Watkins PB, Wrighton SA, Schuetz EG, Molowa DT, and Guzelian PS (1987) Identification of glucocorticoid-inducible cytochromes P-450 in the intestinal mucosa of rats and man. J Clin Investig 80: 1029-1036.
    OpenUrlPubMed
  29. ↵
    Yokogawa K, Shimada T, Higashi Y, Itoh Y, Masue T, Ishizaki J, Asahi M, and Miyamoto K (2002) Modulation of mdr1a and CYP3A gene expression in the intestine and liver as possible cause of changes in the cyclosporin A disposition kinetics by dexamethasone. Biochem Pharmacol 63: 777-783.
    OpenUrlCrossRefPubMed
  30. ↵
    Zhang QY, Wikoff J, Dunbar D, and Kaminsky L (1996) Characterization of rat small intestinal cytochrome P450 composition and inducibility. Drug Metab Dispos 24: 322-328.
    OpenUrlAbstract
Back to top

In this issue

Download PDF
Article Alerts
Email Article
Citation Tools

Research ArticleArticle

EXPRESSION PROFILES OF DRUG-METABOLIZING ENZYME CYP3A AND DRUG EFFLUX TRANSPORTER MULTIDRUG RESISTANCE 1 SUBFAMILY mRNAS IN RAT SMALL INTESTINE

Kohji Takara, Noriaki Ohnishi, Sayo Horibe and Teruyoshi Yokoyama
Drug Metabolism and Disposition October 1, 2003, 31 (10) 1235-1239; DOI: https://doi.org/10.1124/dmd.31.10.1235
Reddit logo Twitter logo Facebook logo Mendeley logo

Jump to section

Advertisement