Differences between small and large intestine and liver in the inducibility of microsomal enzymes in response to stimulation by phenobarbitone and betanaphthoflavone in the diet

McDanell, Rosemary E.; McLean, A. E. M.

doi:10.1016/0006-2952(84)90558-6

Cited by 30 publications

(10 citation statements)

References 19 publications

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“…In the current study, induction of 7EC O-deethylation (CYP1A) was observed with bNF, 3MC (small intestine and colon), and IR (small intestine), well known AhR ligands (Lin and Lu, 1998;Guengerich et al, 2004;Abdelrahim et al, 2006). This finding is in line with published in vivo studies, in which orally administered bNF or 3MC induced 7EC O-deethylation 2-to 100-fold in small intestine (McDanell and McLean, 1984;Rosenberg, 1991;Spatzenegger et al, 2000).…”

Section: Discussionsupporting

confidence: 92%

Induction of Phase I and II Drug Metabolism in Rat Small Intestine and Colon in Vitro

et al. 2007

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ABSTRACT:The aim of this study was to evaluate drug metabolism in rat small intestinal and colon precision-cut slices during 24 h of incubation and the applicability of these slices for enzyme induction studies. Various parameters were evaluated: intracellular levels of ATP (general viability marker), alkaline phosphatase activity (specific epithelial marker), villin expression (specific epithelial marker), and metabolic rates of 7-ethoxycoumarin (CYP1A), testosterone (CYP3A and CYP2B), and 7-hydroxycoumarin (glucuronide and sulfate conjugation) conversions. ATP and villin remained constant up to, respectively, 5 and 8 h in small intestine and up to 24 h in colon. The metabolic rate remained constant in small intestinal slices up to 8 h and decreased afterward to 24 to 92%, depending on the substrate studied. The inducibility of metabolism in small intestinal and colon slices was tested with several inducers at various concentrations and incubation times. The following inducers were used: 3-methylcholanthrene, ␤-naphthoflavone, indirubin, and tertbutylhydroquinone (aryl hydrocarbon receptor ligands), dexamethasone (glucocorticoid receptor/pregnane X receptor ligand) and phenobarbital (constitutive androstane receptor ligand). After incubation with inducers, metabolic rates were evaluated with 7-ethoxycoumarin and testosterone (phase I) and 7-hydroxycoumarin (phase II) as substrate. All inducers elevated the metabolic rates consistent with the available published in vivo induction data. Induction of enzyme activity was already detectable after 5 h (small intestine) and after 8 h (colon) for 3-methylcholanthrene and ␤-naphthoflavone and was clearly detectable for all tested inducers after 24 h (up to 20-fold compared with noninduced controls). In conclusion, small intestinal and colon precision-cut slices are useful for metabolism and enzyme induction studies.

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Section: Discussionsupporting

confidence: 92%

Induction of Phase I and II Drug Metabolism in Rat Small Intestine and Colon in Vitro

et al. 2007

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“…Administered in vivo, ␤NF was reported to significantly induce CYP1A1 mRNA, protein, and activity (Zhang et al, 1997) and 7EC O-deethylation in small intestine (Borm et al, 1983) and colon (McDanell and McLean, 1984). Our finding is also consistent with the induction of CYP1A1/1A2 and 2B1 mRNA by ␤NF in intestinal slices reported by Martignoni et al (2004).…”

Section: Discussionsupporting

confidence: 90%

Characterization of Rat Small Intestinal and Colon Precision-Cut Slices as an in Vitro System for Drug Metabolism and Induction Studies

Kerkhof¹,

Graaf²,

Jager³

et al. 2005

Drug Metab Dispos

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ABSTRACT:The aim of this study was to characterize rat small intestinal and colon tissue slices as a tool to study intestinal metabolism and to investigate gradients of drug metabolism along the intestinal tract as well as drug-induced inhibition and induction of biotransformation. Tissue morphology and the intestinal mucus layer remained intact in small intestinal and colon slices during 3 h of incubation, while alkaline phosphatase was retained and the rate of metabolism of three model compounds (7-hydroxycoumarin, 7-ethoxycoumarin, and testosterone) appeared constant. Phase I and phase II metabolic gradients, decreasing from stomach toward colon were shown to be clearly different for the model compounds used. Furthermore, the observed slice activities were similar or even higher compared with the literature data concerning metabolism of in vitro intestinal systems. Preincubation with ␤-naphthoflavone for 24 h induced the O-deethylation of 7-ethoxycoumarin from nearly undetectable to 140 pmol/min/mg protein in small intestine (fresh slices, 43 pmol/min/mg protein) and to 100 pmol/min/mg protein in colon slices (fresh slices, undetectable). Ketoconazole inhibited metabolism of testosterone by 40% and that of 7-ethoxycoumarin by 100%. In conclusion, we showed that the intestinal slice model is an excellent model to study drug metabolism in the intestine in vitro, since we found that the viability parameters remain constant and the measured enzyme activities are relevant, sensitive to inhibitors, and inducible. Therefore, it is a promising tool to study intestinal drug metabolism in human intestine in vitro in the future.

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“…S9 fractions are generally incubated between 5 min [171] and 30 min [168] and co-factors, such as NADPH generating system, UDPGA, PAPS etc are added to the incubation medium [168]. No information is provided stating whether S9 fractions can be incubated for longer incubation periods.…”

Section: S9 Homogenatesmentioning

confidence: 99%

“…Subsequently, mucosal cells are gently scraped off with a glass slide [17,[170][171][172]. The scrapings are dipped in buffer containing PMSF, trypsin inhibitor, leupeptine, aprotinin, bestatin, glycerol and microsomes are prepared [172].…”

Section: Subcellular Fractionsmentioning

confidence: 99%

In Vitro Methods to Study Intestinal Drug Metabolism

Kerkhof¹,

Graaf²,

Groothuis

2007

CDM

108

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Although the liver has long been thought to play the major role in drug metabolism, also the metabolic capacity of the intestine is more and more recognized. In vivo studies eventually pointed out not only the significance of first-pass metabolism by the intestinal wall for the bioavailability of several compounds, but also the relevance of transporters in this process. Only a few methods are available to study drug metabolism in vivo or in situ and with most of these methods it remains difficult to discriminate between the contribution of liver and extrahepatic tissues. To study intestinal drug metabolism in vitro, apart from subcellular fractions, several intact cell systems are nowadays available. This review discusses the available intestinal in vitro methods to study drug metabolism. The advantages and limitations of intact cell systems (isolated intestinal perfusion, everted sac, Ussing chamber preparations, biopsies, precision-cut slices, primary cells), subcellular fractions (S9 fractions, microsomes) and intestinal cell lines (caco-2, LS180 cells amongst others) are discussed. Their applicability to different species and to study phase I and II metabolism/transport and drug-drug interactions are summarized. Furthermore, causes of variation within and between methods are discussed and metabolic rates obtained with different methods are compared. Whereas subcellular fractions and cell lines are efficient methods to study mechanistic aspects of drug metabolism at the enzyme level, the isolated intestinal perfusion, everted sac and Ussing chamber appear particularly useful for studying drug metabolism of rapidly metabolised drugs and interactions with transporters. Biopsies, precision-cut slices and primary cells seem all appropriate to study induction and metabolism of slowly metabolised drugs.

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Differences between small and large intestine and liver in the inducibility of microsomal enzymes in response to stimulation by phenobarbitone and betanaphthoflavone in the diet

Cited by 30 publications

References 19 publications

Induction of Phase I and II Drug Metabolism in Rat Small Intestine and Colon in Vitro

Induction of Phase I and II Drug Metabolism in Rat Small Intestine and Colon in Vitro

Characterization of Rat Small Intestinal and Colon Precision-Cut Slices as an in Vitro System for Drug Metabolism and Induction Studies

In Vitro Methods to Study Intestinal Drug Metabolism

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