title: Expression and activity of microsomal epoxide hydrolase in follicles isolated from mouse ovaries.
abstract: Microsomal epoxide hydrolase (mEH) is involved in the detoxification of xenobiotics that are or can form epoxide metabolites, including the ovotoxicant, 4-vinylcyclohexene (VCH). This industrial chemical is bioactivated by hepatic CYP450 to the diepoxide metabolite, VCD, which destroys mouse small preantral follicles (F1). Since ovarian mEH may play a role in VCD detoxification, these studies investigated the expression and activity of mEH in isolated ovarian fractions. Mice were given 1 or 15 daily doses (ip) of VCH (7.4 mmol/kg/day) or VCD (0.57 mmol/kg/day); 4 h following the final dose, ovaries were removed, distinct populations of intact follicles (F1, 25-100 microm; F2, 100-250 microm; F3, > 250 microm) and interstitial cells (Int) were isolated, and total RNA and protein were extracted. Real-time polymerase chain reaction and the substrate cis-stilbene oxide (CSO; 12.5 microM) were used to evaluate expression and specific activity of mEH, respectively. Confocal microscopy evaluated ovarian distribution of mEH protein. Expression of mRNA encoding mEH was increased in F1 (410 +/- 5% VCH; 292 +/- 5% VCD) and F2 (1379 +/- 4% VCH; 381 +/- 11% VCD) follicles following repeated dosing with VCH or VCD. Catalytic activity of mEH increased in F1 follicles following repeated dosing with VCH/VCD (381 +/- 11% VCH; 384 +/- 27% VCD). Visualized by confocal microscopy, mEH protein was distributed throughout the ovary with the greatest staining intensity in the interstitial cells and staining in the theca cells that was increased by dosing (56 +/- 0.8% VCH; 29 +/- 0.9% VCD). We conclude that mEH is expressed and is functional in mouse ovarian follicles. Additionally,in vivo dosing with VCH and VCD affects these parameters.
authors.affiliation: University of Arizona, Department of Pharmacology and Toxicology, Tucson 85721, USA.
authors.forename: Ellen A
authors.initials: EA
authors.lastname: Cannady
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Dyer
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Christian
authors.forename: I Glenn
authors.initials: IG
authors.lastname: Sipes
authors.forename: Patricia B
authors.initials: PB
authors.lastname: Hoyer
mesh_terms: D000818:Animals; D003510:Cyclohexanes / Q000633:toxicity; D053138:Cyclohexenes; D004851:Epoxide Hydrolases / Q000235:genetics / Q000378:metabolism*; D005260:Female; D051379:Mice; D008815:Mice, Inbred Strains; D018613:Microscopy, Confocal; D006080:Ovarian Follicle / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014753:Vinyl Compounds / Q000633:toxicity
chemical_list: D003510:Cyclohexanes; D053138:Cyclohexenes; D012333:RNA, Messenger; D014753:Vinyl Compounds; C013733:4-vinylcyclohexene; C012606:4-vinyl-1-cyclohexene dioxide; D004851:Epoxide Hydrolases