Regulation of gender-dependent CYP2A expression in pigs: involvement of androgens and CAR.

Publisher: Blackwell Country of Publication: England NLM ID: 101208422 Publication Model: Print Cited Medium: Print ISSN: 1742-7835 (Print) Linking ISSN: 17427835 NLM ISO Abbreviation: Basic Clin Pharmacol Toxicol Subsets: MEDLINE

Publication: <2005-> : Oxford : Blackwell
Original Publication: Copenhagen, Denmark : Oxford, UK : Nordic Pharmacological Society Distributed by Blackwell Munksgaard, 2004-

Gene Expression Regulation, Enzymologic*; Aryl Hydrocarbon Hydroxylases/*metabolism ; Liver/*drug effects ; Oximes/*pharmacology ; Receptors, Cytoplasmic and Nuclear/*agonists ; Steroid Hydroxylases/*metabolism ; Swine, Miniature/*metabolism ; Thiazoles/*pharmacology ; Transcription Factors/*agonists; Animals ; Aryl Hydrocarbon Hydroxylases/genetics ; Cells, Cultured ; Constitutive Androstane Receptor ; Coumarins/metabolism ; Cytochrome P-450 CYP3A/genetics ; Cytochrome P-450 CYP3A/metabolism ; Dose-Response Relationship, Drug ; Hepatocytes/drug effects ; Hepatocytes/enzymology ; Humans ; Liver/enzymology ; Male ; Orchiectomy ; Phenobarbital/pharmacology ; Pregnane X Receptor ; RNA, Messenger/metabolism ; Receptors, Cytoplasmic and Nuclear/metabolism ; Receptors, Steroid/metabolism ; Sex Factors ; Steroid Hydroxylases/genetics ; Swine ; Transcription Factors/metabolism

The expression of drug metabolizing cytochrome P4502A (CYP2A) is highly gender-dependent in minipigs with the highest activity in females. In other species, orthologs of CYP2A have been shown to be under the regulation of nuclear receptor constitutive androstane receptor, whereas little is known about regulation in pigs. To investigate the effect of sex hormones on porcine cytochrome P450 CYP2A and CYP3A expression was assessed in liver samples taken before and after castration of sexually mature minipig boars. Removal of the primary androgen source resulted in significant increases of CYP2A mRNA, protein and enzyme activity levels. Likewise, expression of CYP3A was increased, although to a lesser extent. To examine the involvement of constitutive androstane receptor in the regulation of CYP2A, primary porcine hepatocytes were exposed to modulators of murine constitutive androstane receptor and human constitutive androstane receptor activity. The CYP2A activity was significantly increased by exposure to phenobarbital, an indirect activator of constitutive androstane receptor, and the human constitutive androstane receptor-ligand CITCO. In contrast, no effect was seen following exposure to the potent murine constitutive androstane receptor-ligand TCPOBOP and the hormonal murine constitutive androstane receptor-ligands androstenol and oestrone. Thus, the results support that 1) porcine CYP2A is reversibly inhibited by androgens on a transcriptional basis in vivo; 2) the induction profile of CYP2A in vitro shares similarity with that of human constitutive androstane receptor-regulated CYPs, indicating an involvement of a porcine constitutive androstane receptor in the regulation of CYP2A.

0 (Constitutive Androstane Receptor)
0 (Coumarins)
0 (Oximes)
0 (Pregnane X Receptor)
0 (RNA, Messenger)
0 (Receptors, Cytoplasmic and Nuclear)
0 (Receptors, Steroid)
0 (Thiazoles)
0 (Transcription Factors)
D77H8321PB (6-(4-chlorophenyl)imidazo(2,1-b)(1,3)thiazole-5-carbaldehyde O-(3,4-dichlorobenzyl)oxime)
EC 1.14.- (Steroid Hydroxylases)
EC 1.14.14.1 (Aryl Hydrocarbon Hydroxylases)
EC 1.14.14.1 (Cytochrome P-450 CYP3A)
EC 1.14.14.1 (steroid hormone 7-alpha-hydroxylase)
YQE403BP4D (Phenobarbital)

Date Created: 20060426 Date Completed: 20061207 Latest Revision: 20211203

20221213

10.1111/j.1742-7843.2006.pto_261.x

16635107