ToxSci Advance Access published online on April 15, 2003
Toxicological Sciences, doi:10.1093/toxsci/kfg077
Toxicological Sciences © Society of Toxicology 2003; all rights reserved
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 University of Arizona, Department of Pharmacology and Toxicology, Tucson, Arizona, 85721, USA
* To whom correspondence should be addressed. E-mail: hoyer{at}u.arizona.edu.
4-Vinylcyclohexene (VCH), an occupational chemical, causes destruction of small pre-antral follicles (F1) in mice. Previous studies suggested that VCH is bioactivated via cytochromes P450 (Cyp 450) to the ovotoxic, diepoxide metabolite, VCD. Whereas hepatic Cyp 450 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, 25-100µm; F2, 100-250µm; F3, >250µm; interstitial cells; Int) from B6C3F1 mice dosed daily (15 d; ip) with vehicle, VCH (7.4 mmol/kg/d) or VCD (0.57 mmol/kg/d). 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 Cyp 2E1 (645±14% VCH; 582±16% VCD), Cyp 2A (689+8% VCH; 730±22% VCD), and Cyp 2B (246±7% VCH) above control. VCH dosing altered (p<0.05) mRNA encoding Cyp 2E1 in non-targeted F3 follicles (168±7%) and Cyp 2A 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 Cyp 2E1 (19±2.4% below control) and Cyp 2A (39±5% above control). Staining intensity for Cyp 2B was increased (p<0.05) above control in granulosa cells of small pre-antral (187±42%) and antral (63±8%) follicles. Catalytic assays in ovarian homogenates revealed that Cyp 2E1 and Cyp 2B were functional. Only Cyp 2E1 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.
© 2003 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
2 Northern Arizona University, Department of Biological Sciences, Flagstaff, Arizona, 86011, USA
3 University of Arizona, Department of Physiology, Tucson, Arizona, 85724, USA
Abstract 
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]
|
|