Western Diet Decreases Hepatic Drug Metabolism in Male LDLr-/-ApoB100/100 Mice

Abstract

Consumption of a Western diet is an important risk factor for several chronic diseases including nonalcoholic fatty liver disease (NAFLD), but its effect on the xenobiotic metabolizing enzyme activities in the liver has been studied incompletely. In this study, male LDLr^-/-ApoB^100/100 mice were fed with Western diet (WD) or a standard diet for five months to reveal the effects on drug metabolism such as cytochrome P450 (CYP) oxidation and conjugation activities in the liver. Hepatic steatosis, lobular inflammation, and early fibrosis were observed in WD fed mice, but not in chow diet control mice. When compared to the controls, the WD-fed mice had significantly decreased protein-normalized CYP probe activities of 7-ethoxyresorufinO-deethylation (52%), coumarin 7-hydroxylation (26%), 7-hydroxylation of 3-(3-fluoro-4-hydroxyphenyl)-6-methoxycoumarin (70%), 7-hydroxylation of 3-(4-trifluoromethoxyphenyl)-6-methoxycoumarin (78%), 7-hydroxylation of 3-(3-methoxyphenyl)coumarin (81%), and pentoxyresorufin O-depentylation (66%). Increased activity was seen significantly in sulfonation of 3-(4-methylphenyl)-7-hydroxycoumarin (289%) and cytosol catechol O-methyltranferase (COMT, 148%) in the WD group when compared to the controls. In conclusion, the WD-induced steatosis in male LDLr^-/-ApoB^100/100 mice was associated with decreased CYP oxidation reactions but had no clear effects on conjugation reactions of glucuronidation, sulfonation, and cytosolic catechol O-methylation. Consequently, the WD may decrease the metabolic elimination of drugs compared to healthier low-fat diets.

Figure 1

Prolonged Western diet (WD) induces hepatic steatosis in male LDLr^−/−ApoB^100/100 mice. LDLr^−/−ApoB^100/100 male mice were fed the WD for 5 months. When detecting hepatic steatosis, liver sections were stained with hematoxylin-eosin (a) on a chow diet and (b) after 5 months on the WD. When determining liver fibrosis, liver sections (c) on a chow and (d) after the WD was stained with Masson trichrome stain that designates fibrosis with blue color (arrow). The WD induced high increase in hepatic lipid accumulation and infiltration of inflammatory cells (arrowhead) and promoted liver fibrosis. Representative pictures of livers are shown with a scale bar 200 μm.

Figure 2

The effect of consumption of the Western diet (WD) on the probe protein-normalized activities of CYP enzymes in the liver microsomes of male LDLr^−/−ApoB^100/100 mice. The liver microsomes were prepared from the livers of eight months old mice; the animals were fed either with the WD or the chow diet for five months. CYP-oxidized reactions were determined with the indicated probe substrates: 7-ethoxyresorufin, 7-pentoxyresorufin, coumarin, 3-(4-trifluoromethoxyphenyl)-6-methoxycoumarin, 3-(3-benzyloxo)phenyl-7-methoxycoumarin, 3(3-fluoro-4-hydroxyphenyl)-6-methoxycoumarin, and 3-(3-methoxyphenyl)coumarin. ^∗, p < 0.05; ^∗∗, p < 0.01; and ^∗∗∗, p < 0.001 WD vs. chow diet. The lines of the groups represent geometrical means with 95% confidence interval: (a) 7-ethoxyresorufin, (b) coumarin, (c) 7-pentoxyresorufin, (d) 3-(3-methoxyphenyl)-coumarin, (e) 3-(3-fluoro-4-hydroxyphenyl)-6-methoxycoumarin, (f) 3-(4-trifluoromethoxyphenyl)-6-methoxycoumarin, and (g) 3-(3-benzyloxo)phenyl-7-methoxycoumarin.

Figure 3

The effect of the Western diet (WD) on the probe activities of conjugation enzymes in the liver cytosol or microsomes of male LDLr^−/−ApoB^100/100 mice. The liver microsome or cytosol samples were prepared from livers of eight months old mice; the animals were fed either with the WD or the chow diet for five months. Glucuronidation, sulfonation, and catechol (O)-methylation (COMT) activities determined with the indicated probe substrates. ^∗, p <0.05 ^∗∗∗, p < 0.001 WD vs. chow diet. The lines of the groups represent geometrical means with 95% confidence interval: (a) glucuronidation of 7-hydroxy-4-trifluoromethylcoumarin, (b) glucuronidation of 3-(1H-1,2,4-triazol-1-yl)7-hydroxycoumarin, (c) sulfonation of 7-hydorxy-4-trifluoromethylcoumarin. (d) sulfonation of 3-(4-methylphenyl)-7-hydroxycoumarin, (e) cytosolic COMT, and (f) Microsomal COMT.

Figure 4

Multivariate analysis separated the Western diet (WD) fed male LDLr^−/−ApoB^100/100 mice into low xenobiotic metabolism activity group in contrast to mice fed with the chow diet. Biplots showing the first two latent components of the principal component analysis ((a) cumulative R²X = 0.99 and cumulative Q² = 0.58) and a partial least sum of squares discriminant analysis ((b) cumulative R²Y = 0.86 and cumulative Q² = 0.66) of CYP oxidation, glucuronidation, sulfonation, and COMT activities in liver of control and WD male LDLr^−/− ApoB^100/100 mice. Explanations of the symbols: C1 = ethoxyresorufin 7-(O)-deethylation, C2 = 7-hydroxylation of 3-(4-trifluoromethoxyphenyl)-6-methoxycoumarin, C3 = 7-hydroxylation of 3-(3-fluoro-4-hydroxyphenyl)-6-methoxycoumarin, C4 = coumarin 7-hydroxylation, C5 = pentoxyresorufin 7-(O)-depentylation, C6 = 7-hydroxylation of 3-(3-methoxyphenyl)coumarin, C7 = 7-(O)-demethylation of 3-(3-benzyloxo)phenyl-7-methoxycoumarin, G1 = HFC glucuronidation, G2 = 3-(1H-1, 2, 4-triazol-1-yl)-7-hydroxycoumarin glucuronidation, S1 = HFC sulfonation, S2 = 3-(4-methylphenyl)-7-hydroxycoumarin sulfonation, Cs = cytosol COMT, and Cm = microsomal COMT.

Figure 5

Statistically significant linear correlations between the oxidation rates of two probe substrates in liver microsomes in Figure 2 and Table 2.