<i>In Vitro</i> Cytochrome P450 2E1 and 2A Activities in the Presence of Testicular Steroids

Rasmussen, Martin Krøyer; Zamaratskaia, Galia; Ekstrand, Bo

doi:10.1111/j.1439-0531.2010.01613.x

Cited by 24 publications

(47 citation statements)

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“…It is likely that the higher CYP450 activity (for at least some isoforms) is due to the absence or low levels of testicular steroids, which otherwise inhibit CYP450 expression at the level of transcription (Tambyrajah et al, 2004;Gillberg et al, 2006;Kojima et al, 2008). Moreover, testicular steroids, particularly androstenone and oestradiol, are directly involved in the regulation of CYP2E1 activities (Zamaratskaia et al, 2007 andRasmussen et al, 2011b). It should be emphasised that other steroids of testicular origin, as well as growth hormone and IGFs, may also be relevant in such regulation.…”

Section: Discussionmentioning

confidence: 99%

“…Androstenone and oestrogens, which are produced in high amounts in the testicles of male pigs, were suggested to be particularly important in this modulation (Zamaratskaia et al, 2007 and. Studies investigating the interaction between testicular steroids and selected CYP450 have shown an effect both in vitro (Doran et al, 2002a;Zamaratskaia et al, 2007;Chen et al, 2008;Rasmussen et al, 2011b) and in vivo (Whittington et al, 2004;Kojima et al, 2008;Zamaratskaia et al, 2008 and. However, whether the in vivo effect of testicular steroids on hepatic enzymes is mediated by the hormones themselves, or indirectly through other agents, such as growth hormone or IGFs, is not known.…”

Section: Introductionmentioning

confidence: 99%

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Expression and activities of hepatic cytochrome P450 (CYP1A, CYP2A and CYP2E1) in entire and castrated male pigs

Brunius

Rasmussen

Lacoutière

et al. 2012

Animal

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This study aimed to provide further insights into the mechanism of in vivo regulation of cytochrome P450 (CYP450) 1A, 2A and 2E1 activities in pigs with different levels of testicular steroids. Hepatic mRNA and protein expression and enzymatic activity of CYP1A, CYP2A and CYP2E1 were compared between entire male and castrated pigs. Castration was performed either surgically or immunologically. The pigs were divided into four groups. In the first group, piglets were surgically castrated without anaesthesia. Immunological castration was performed by vaccination with Improvac R (Pfizer Ltd). Vaccinated pigs were subdivided into two groups according to the vaccination regimen: early and standard vaccination. Pigs in the early vaccination group were vaccinated when aged 11 and 15 weeks. Pigs in the standard vaccination group were vaccinated when aged 17 and 21 weeks. In the control group, pigs remained intact throughout the study. Hepatic CYP450 mRNA expression, measured by real-time RT-PCR, differed significantly between groups for all isoforms measured: CYP1A2 (P 5 0.002), 2A (P 5 0.000) and 2E1 (P 5 0.002). Lower CYP450 mRNA in entire male pigs suggests suppression of CYP1A2, CYP2A and CYP2E1 by testicular steroids at the transcriptional level. However, this suppression was not always reflected in decreased protein expression and activities of these isoforms, suggesting that at least some CYP450s (e.g. CYP2E1) are regulated by a post-transcriptional mechanism.Keywords: male pigs, testicular steroids, liver, cytochrome P450 ImplicationsWe studied in vivo regulation of cytochrome P450 (CYP450) 1A, 2A and 2E1 activities in uncastrated male pigs with high concentrations of testicular steroids, and surgically and immunologically castrated pigs with low steroid concentrations. We confirmed an association between steroids and CYP450 expression. We suggest that this regulation occurs at the transcriptional level, as indicated by suppressed CYP450 mRNA in uncastrated pigs. This suppression was not always reflected in decreased activities, suggesting that at least some CYP450s (e.g. CYP2E1) are regulated by a post-transcriptional mechanism. These results contribute to the knowledge on porcine CYP450 and its in vivo regulation by testicular steroids.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Expression and activities of hepatic cytochrome P450 (CYP1A, CYP2A and CYP2E1) in entire and castrated male pigs

Brunius

Rasmussen

Lacoutière

et al. 2012

Animal

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“…Animals were raised under the same conditions and slaughtered at the same age. For details about the animals and specific CYP450 expression and activity, see Rasmussen et al (2011b) and Rasmussen et al (2012).…”

Section: Methodsmentioning

confidence: 99%

“…These inhibitors have previously been shown to have an effect on the activities of CYP450 isoforms in microsomal or hepatocyte assays Rasmussen et al, 2011b;Zlabek and Zamaratskaia, 2012). The incubations were performed in the presence of 0.125, 1.25 and 12.5 µM of the specific inhibitor, except for E2 (used concentration 0.002, 0.02 and 0.2 µM) and quercetin (16, 32 and 128 µM).…”

Section: Microsomal Incubations With Cyp450 Isoform Inhibitorsmentioning

confidence: 99%

“…These differences are suggested to be because of the higher concentrations of sex steroids in male pigs (Skaanild and Friis, 1999;Rasmussen et al, 2011a). Until recently, we believed that this is because of the inhibition of skatole metabolism by high oestrogen levels found in uncastrated male pigs (Zamaratskaia et al, 2007;Rasmussen et al, 2011b). However, a recent in vivo study showed no differences in CYP1A, CYP2A and CYP2E1 activities in male pigs with physiological and artificially reduced oestrogen levels (Zamaratskaia and Berger, 2014).…”

Section: Introductionmentioning

confidence: 97%

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Gender-related differences in the formation of skatole metabolites by specific CYP450 in porcine hepatic S9 fractions

Borrisser-Pairó¹,

Rasmussen

Ekstrand

et al. 2015

Animal

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Higher accumulation of skatole in the fat of male pigs compared with female pigs might be due to gender-related differences in the rate of skatole degradation. In the present study, skatole metabolites and cytochrome P450 (CYP450) isoforms involved in skatole metabolism were for the first time investigated in hepatic S9 fractions from six male and four female pigs (crossbred Landrace × Yorkshire dams and Duroc boar). Surprisingly, the rates of production of major skatole metabolites were similar in male and female pigs. The most abundant metabolite of skatole was 3-hydroxy-3-methyloxindole (HMOI) followed by 3-methyloxindole and indole-3-carbinol in both male and female S9 fractions. Concentrations of formed HMOI and 3-methyloxindole did not differ between the genders (P = 0.124 for HMOI, and P = 0.575 for 3-methyloxindole). Indole-3-carbinol formation was higher in S9 fractions from the females compared with male pigs (P = 0.0001). Enzyme kinetic parameters were similar for both genders (P > 0.05). In both male and female pigs, ellipticine, diallyl sulphide (DAS) and quercetin inhibited HMOI formation, confirming the involvement of CYP1A1 and CYP2E1. The formation of 3-methyloxindole was reduced in the presence of the CYP2E1 inhibitor DAS, and formation of indole-3-carbinol was reduced in the presence of CYP1A1 and CYP2A19 inhibitors. We found only minor differences in skatole metabolism between male and female pigs, particularly the involvement of CYP2C and CYP3A in indole-3-carbinol formation in female but not in male pigs. This is a very essential finding, suggesting the involvement of larger number of CYP450 isoforms in female pigs. On the other hand, indole-3-carbinol is a minor skatole metabolite, and the physiological significance of CYP2C and CYP3A involvement in its formation in female pigs, but not in male pigs, needs to be elucidated. Our results, however, should be interpreted with caution because of the low number of animals and possibility of breed and age effects on skatole metabolism.Keywords: boar taint, skatole, 3-methyloxindole, indole-3-carbinol, 3-hydroxy-3-methyloxindole, CYP450 isoforms ImplicationsWe studied skatole metabolism in hepatic S9 fractions from male and female pigs. Generally, skatole levels are higher in entire male than in female pigs. Until recently, we believed that this is because of the differences in skatole metabolism between male and female pigs. The present study suggests that production of skatole metabolites is similar in both male and female pigs. We found only minor differences in skatole metabolism, particularly the involvement of CYP2C and CYP3A in indole-3-carbinol formation. These results contribute to the knowledge on skatole metabolism by CYP450 and are of interest for animal and meat scientists.

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Para-nitrophenol hydroxylation by fish liver microsomes: kinetics and effect of selective cytochrome P450 inhibitors

Zamaratskaia

Žlábek

2011

Fish Physiol Biochem

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The study investigated the kinetics of p-nitrophenol hydroxylase (PNPH) in hepatic microsomes obtained from Atlantic salmon (Salmo salar). The selective inhibitors for some major mammalian cytochrome P450 (CYP450) were used to investigate the potential inhibitory effect on enzymes involved in p-nitrophenol hydroxylation. The following inhibitors were used: α-naphtoflavone (CYP1A), ellipticine (CYP1A1), furafylline (CYP1A2), 8-methoxypsoralen (8MOP, CYP2A6), 4-methylpyrazole (4MP, CYP2A6/2E1), diallyl sulfide (DAS, CYP2E1), and ketoconazole (CYP3A4). Additionally, the natural steroids 17-beta-oestraiol (E2) and testosterone were investigated as potential inhibitors of PNPH activity. It was found that formation of 4-nitrocatechol from p-nitrophenol followed monophasic kinetics with K(m) = 0.17 ± 0.03 mM and V(max) = 21.8 ± 1.05 pmol/min/mg. PNPH activity was competitively inhibited by diallyle sulfide with the K(i) value of 285.1 ± 94.2 μM μM and uncompetitively by ellipticine with K(i) value of 65.7 ± 7.8 μM. Moreover, E2 showed an ability to reduce PNPH activity through the mechanism-based inhibition mode. Our results suggest that hepatic microsomes from Atlantic salmon possess CYP2E1-like activity. However, specific isoform-mediated PNPH activity should be identified.

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In Vitro Cytochrome P450 2E1 and 2A Activities in the Presence of Testicular Steroids

Cited by 24 publications

References 29 publications

Expression and activities of hepatic cytochrome P450 (CYP1A, CYP2A and CYP2E1) in entire and castrated male pigs

Expression and activities of hepatic cytochrome P450 (CYP1A, CYP2A and CYP2E1) in entire and castrated male pigs

Gender-related differences in the formation of skatole metabolites by specific CYP450 in porcine hepatic S9 fractions

Para-nitrophenol hydroxylation by fish liver microsomes: kinetics and effect of selective cytochrome P450 inhibitors

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