title: CYP1B1 expression in rat testis and Leydig cells is not inducible by aryl hydrocarbon receptor agonists.
abstract: 1. Cytochrome P450 1B1 (CYP1B1) is highly expressed in testis, but there is conflicting information regarding the inducibility of testicular CYP1B1 by aryl hydrocarbon receptor (AhR) agonists. 2. To assess AhR-mediated regulation, testicular CYP1B1 expression was measured following treatment of adult rats with 3-methylcholanthrene and various dosages of benzo[a]pyrene and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The effect of TCDD on CYP1B1 expression in R2C rat Leydig and MA-10 mouse Leydig cells in culture was also determined. 3. Immunoblot analysis showed that treatment with benzo[a]pyrene at dosages up to 200 mg/kg/day and 3-methylcholanthrene at 25 mg/kg/day did not induce testicular CYP1B1 expression. Treatment with TCDD at dosages of 1, 5 or 100 microg/kg had no effect, but testicular CYP1B1 protein levels were increased by approximately 50% at dosages of 10 and 50 microg/kg. 4. CYP1B1 mRNA levels in MA-10 and CYP1B1 protein levels in R2C cells were not induced by exposure to TCDD (10-1000 nM). 5. Overall, the results indicate that rodent testicular CYP1B1 is not inducible by AhR agonists.
authors.affiliation: Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Deb
authors.forename: M
authors.initials: M
authors.lastname: Kawai
authors.forename: T K H
authors.initials: TK
authors.lastname: Chang
authors.forename: S M
authors.initials: SM
authors.lastname: Bandiera
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism*; D001564:Benzo(a)pyrene / Q000494:pharmacology; D002460:Cell Line; D065633:Cytochrome P-450 CYP1B1; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects* / Q000502:physiology; D015151:Immunoblotting; D007985:Leydig Cells / Q000378:metabolism*; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology; D051379:Mice; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018336:Receptors, Aryl Hydrocarbon / Q000819:agonists*
chemical_list: D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D001564:Benzo(a)pyrene; D008748:Methylcholanthrene; D001189:Aryl Hydrocarbon Hydroxylases; C585498:Cyp1b1 protein, mouse; C585499:Cyp1b1 protein, rat; D065633:Cytochrome P-450 CYP1B1