Metabolism of human cytochrome P450 marker substrates in mouse: a strain and gender comparison

Abstract

The aim was to characterize mouse gender and strain differences in the metabolism of commonly used human cytochrome (CYP) P450 probe substrates. Thirteen human CYP probe substrates (phenacetin, coumarin, 7-ethoxy-4-trifluoromethyl coumarin, amiodarone, paclitaxel, diclofenac, S-mephenytoin, bufuralol, dextromethorphan, chlorzoxazone, p-nitrophenol, testosterone and lauric acid) were used in activity measurements. The metabolism of the probe substrates was compared in liver microsomes from male and female NMRI, CBA, C57bl/6, 129/SvJ and CD1 strains. The expression of proteins identified on Western blots with commonly available antibodies selective for specific human and rat CYP enzymes were compared in the different mouse strains. Males had higher metabolism than corresponding females for phenacetin O-deethylation (human marker for CYP1A2 activity), and a high correlation was found between phenacetin activity and immunoreactivity in Western blots produced with rat CYP1A2 antibodies. Protein detected by antibodies cross-reacting with human CYP2B6 and rat CYP2B1/2 antibodies was female specific except for the 129/SvJ strain, where it was absent in both genders. Females generally had a higher metabolism of bufuralol 1'-hydroxylation and dextromethorphan O-demethylation (human markers for CYP2D activity). Bufuralol 1'-hydroxylation correlated with a female-dominant mouse CYP, which was detected with antibodies against rat CYP2D4. p-Nitrophenol 2-hydroxylation correlated better than chlorzoxazone 6-hydroxylation with the protein detected with antibodies against rat CYP2E1, indicating that p-nitrophenol is a more specific substrate for mouse CYP2E1.

Expression, Purification, and Characterization of Mouse Cyp2d22

“…However, Cyp2d22 is known to be highly expressed in both male and female mouse liver and is modestly expressed in a variety of other tissues, such as adrenal, ovary, and mammary glands (Blume et al, 2000). Thus, our results would suggest that Cyp2d22 is not the CYP2D isozyme responsible for the CYP2D6-like enzyme activity reported by Lofgren et al (2004) in female mouse liver.…”

“…Given the sequence similarity with CYP2D6, we reasoned that characterization of the enzymatic function for the encoded Cyp2d22 protein would contribute to the understanding of the CYP2D6-like phenotype or lack thereof in mice. Recently, Lofgren et al (2004) reported CYP2D6-like enzymatic activity in mouse liver microsomes. This activity correlated with a protein that was immunoreactive to anti-rat Cyp2d4 antibody and that appeared more prevalent in females than males (Lofgren et al, 2004).…”

“…Recently, Lofgren et al (2004) reported CYP2D6-like enzymatic activity in mouse liver microsomes. This activity correlated with a protein that was immunoreactive to anti-rat Cyp2d4 antibody and that appeared more prevalent in females than males (Lofgren et al, 2004). However, Cyp2d22 is known to be highly expressed in both male and female mouse liver and is modestly expressed in a variety of other tissues, such as adrenal, ovary, and mammary glands (Blume et al, 2000).…”

Effect of Breed upon Cytochromes P450 and Phase II Enzyme Expression in Cattle Liver

“…As a whole, our data are suggestive of breed differences in DME expression in cattle, likewise to laboratory species (Casley et al, 1997;Jang et al, 2001;Löfgren et al, 2004;Saito et al, 2004;Stott et al, 2004). Differences in DME expression are likely to influence both the bioavailability and clinical efficacy of xenobiotics (Sallovitz et al, 2002), and these same might be of particular concern in farm animals, for the hypothetical presence of potentially harmful residues in foodstuffs of animal origin.…”

Species Differences in the Pharmacokinetic Parameters of Cytochrome P450 Probe Substrates between Experimental Animals, such as Mice, Rats, Dogs, Monkeys, and Microminipigs, and Humans

“…Dextromethorphan is metabolized to dextrorphan by CYP2D mainly in mouse, rat, dog, monkey and pig liver as well as in human liver [14,21,26,55,56]. Therefore we used dextromethorphan and its major metabolite, dextrorphan, is often used as probe drugs to evaluate the activity of the CYP2D isoform.…”