ToxSci Advance Access originally published online on April 15, 2003
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Toxicological Sciences 73, 423-430 (2003)
Copyright © 2003 by the Society of Toxicology
REPRODUCTIVE AND DEVELOPMENTAL TOXICOLOGY |
Expression and Activity of Cytochromes P450 2E1, 2A, and 2B in the Mouse Ovary: The Effect of 4-Vinylcyclohexene and Its Diepoxide Metabolite
,1
* University of Arizona, Department of Pharmacology and Toxicology, Tucson, Arizona 85721;
Northern Arizona University, Department of Biological Sciences, Flagstaff, Arizona 86011; and
University of Arizona, Department of Physiology, Tucson, Arizona 85724
4-Vinylcyclohexene (VCH), an occupational chemical, causes destruction of small preantral follicles (F1) in mice. Previous studies suggested that VCH is bioactivated via cytochromes P450 (CYP450) to the ovotoxic, diepoxide metabolite, VCD. Whereas hepatic CYP450 isoforms 2E1, 2A, and 2B can metabolize VCH, the role of ovarian metabolism is unknown. This study investigated expression of these isoforms in isolated ovarian fractions (F1, 25–100 µm; F2, 100–250 µm; F3, >250 µm; interstitial cells, Int) from B6C3F1 mice dosed daily (15 days; ip) with vehicle, VCH (7.4 mmol/kg/day) or VCD (0.57 mmol/kg/day). Ovaries were removed and either isolated into specific ovarian compartments for mRNA analysis, fixed for immunohistochemistry, or prepared for enzymatic assays. mRNA and protein for all isoforms were expressed/distributed in all ovarian fractions from vehicle-treated mice. In the targeted F1 follicles, VCH or VCD dosing increased (p < 0.05) mRNA encoding CYP2E1 (645 ± 14% VCH; 582 ± 16% VCD), CYP2A (689 ± 8% VCH; 730 ± 22% VCD), and CYP2B (246 ± 7% VCH) above control. VCH dosing altered (p < 0.05) mRNA encoding CYP2E1 in nontargeted F3 follicles (168 ± 7%) and CYP2A in Int (207 ± 19%) above control. Immunohistochemical analysis revealed the greatest staining intensity for all CYP isoforms in the Int. VCH dosing altered (p < 0.05) staining intensity in Int for CYP2E1 (19 ± 2.4% below control) and CYP2A (39 ± 5% above control). Staining intensity for CYP2B was increased (p < 0.05) above control in granulosa cells of small preantral (187 ± 42%) and antral (63 ± 8%) follicles. Catalytic assays in ovarian homogenates revealed that CYP2E1 and CYP2B were functional. Only CYP2E1 activity was increased (149 ± 12% above control; p < 0.05) by VCH dosing. The results demonstrate that mRNA and protein for CYP isoforms known to bioactivate VCH are expressed in the mouse ovary and are modulated by in vivo exposure to VCH and VCD. Interestingly, there is high expression of these isoforms in the Int. Thus, the ovary may contribute to ovotoxicity by promoting bioactivation of VCH to the toxic metabolite, VCD.
Key Words: cytochrome P450; 4-vinylcyclohexene; ovary; ovarian follicles; mouse; confocal microscopy.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  R. D. Finn, L. A. McLaughlin, S. Ronseaux, I. Rosewell, J. B. Houston, C. J. Henderson, and C. R. Wolf Defining the in Vivo Role for Cytochrome b5 in Cytochrome P450 Function through the Conditional Hepatic Deletion of Microsomal Cytochrome b5 J. Biol. Chem., November 14, 2008; 283(46): 31385 - 31393. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. F. Keating, K. S. Rajapaksa, I. G. Sipes, and P. B. Hoyer Effect of CYP2E1 Gene Deletion in Mice on Expression of Microsomal Epoxide Hydrolase in Response to VCD Exposure Toxicol. Sci., October 1, 2008; 105(2): 351 - 359. [Abstract] [Full Text] [PDF]
|
|