<abstract xml:lang="en" xmlns="http://www.w3.org/1999/xhtml"><p>Sexually mature pigs are known to possess high concentrations of testicular steroids, which have been shown to change the activities of cytochrome P450 <italic>in vitro</italic>. The aim of the present study was to evaluate the regulation of CYP1A and CYP2E1 activity by the steroids dihydrotestosterone (DHT), 3β-androstenol, 17β-estradiol and 17α-estradiol. Catalytic activities of 7-ethoxyresorufin O-deethylase (EROD) and 7-methoxyresorufin O-demethylase (MROD) were used as markers of CYP1A activities, while p-nitrophenol hydroxylase (PNPH) was used as a marker of CYP2E1 activities. Of the steroids tested, only 17β-estradiol and 17α-estradiol inhibited EROD and MROD activities. This inhibition was observed when a steroid concentration of 100 μM was used, while lower concentrations showed no inhibitory effect. PNPH activities were inhibited only by 100 μM of 17β-estradiol. The significance of these results in vivo is unknown because inhibition was only found when concentrations of estrogens higher than physiological levels were used. Nevertheless, the results provided further evidence on the important role of estrogens in regulation of porcine cytochrome P450 activities.</p></abstract>

Sexually mature pigs are known to possess high concentrations of testicular steroids, which have been shown to change the activities of cytochrome P450 in vitro. The aim of the present study was to evaluate the regulation of CYP1A and CYP2E1 activity by the steroids dihydrotestosterone (DHT), 3β-androstenol, 17β-estradiol and 17α-estradiol. Catalytic activities of 7-ethoxyresorufin O-deethylase (EROD) and 7-methoxyresorufin O-demethylase (MROD) were used as markers of CYP1A activities, while p-nitrophenol hydroxylase (PNPH) was used as a marker of CYP2E1 activities. Of the steroids tested, only 17β-estradiol and 17α-estradiol inhibited EROD and MROD activities. This inhibition was observed when a steroid concentration of 100 μM was used, while lower concentrations showed no inhibitory effect. PNPH activities were inhibited only by 100 μM of 17β-estradiol. The significance of these results in vivo is unknown because inhibition was only found when concentrations of estrogens higher than physiological levels were used. Nevertheless, the results provided further evidence on the important role of estrogens in regulation of porcine cytochrome P450 activities.

<italic>In vitro</italic> inhibition of porcine cytochrome P450 by 17β-estradiol and 17α-estradiol

Department of Food Science, BioCenter, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden

Department of Food Science, Faculty of Agricultural Sciences, Aarhus University, Denmark

South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Faculty of Fisheries and Protection of Waters, University of South Bohemia in Ceske, Budejovice, 389 25 Vodnany, Czech Republic

Interdisciplinary Toxicology

 inhibition of porcine cytochrome P450 by 17β-estradiol and 17α-estradiol

Sexually mature pigs are known to possess high concentrations of testicular steroids, which have been shown to change the activities of cytochrome P450 in...

In vitro inhibition of porcine cytochrome P450 by 17β-estradiol and 17α-estradiol

Online veröffentlicht: 17. Juni 2011

Seitenbereich: 78 - 84

DOI: https://doi.org/10.2478/v10102-011-0014-x

Schlüsselwörter
pig, liver, microsomes, cytochrome P450, steroid hormones

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