The methoxychlor metabolite, 2,2-bis-(p-hydroxyphenyl)-1,1,1-trichloroethane, inhibits steroidogenesis in rat ovarian granulosa cells in vitro
The exquisitely balanced hormonal mechanisms that control female fertility can be affected by several internal and external factors including pathogens, genetic maladies, and environmental agents. In the latter group are natural and synthetic agents known as endocrine disruptors. One such compound, 2,2-bis-(p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE), is the predominant metabolite of the pesticide methoxychlor. The effects of HPTE on ovarian steroidogenesis have not been previously reported and were investigated in the present study. Granulosa cells harvested from immature rats were treated with follicle-stimulating hormone (FSH) or N(6),2'-O-dibutyryladenosine 3',5'-cyclic monophosphate (db-cAMP) in the presence or absence of HPTE. After 48h, progesterone (P4) and estradiol-17beta (E2) concentrations were measured in the culture media. Steady-state levels of the mRNAs encoding steroidogenic acute regulatory protein (StAR), P450 side-chain cleavage (P450scc), 3beta-hydroxysteroid dehydrogenase type 1 (3beta-HSD), and P450 aromatase (P450arom) were examined using real-time PCR. Both FSH- and db-cAMP-stimulated P(4) accumulation were impaired by HPTE. In contrast, FSH-, but not db-cAMP-stimulated, E2 content was suppressed by HPTE. The FSH-dependent increase in the abundance of P450scc, 3beta-HSD, and P450arom mRNAs was blocked by HPTE; however, StAR expression was not altered. Although db-cAMP-dependent P450arom was moderately reduced by HPTE, the levels of db-cAMP-dependent StAR, P450scc, and 3beta-HSD mRNAs were increased in the presence of HPTE. These data collectively show that HPTE can disrupt P4 and E2 production in granulosa cells, with implications for sites of action both preceding and following the generation of cAMP. The steroid-modulatory effects of HPTE in granulosa cells appear to involve the general suppression of the FSH-dependent expression of mRNAs encoding steroid pathway proteins, whereas the disparate effects of HPTE on cAMP-dependent mRNA content in this regard suggest a broader and more complex mechanism of action.