Influence of dichlorodiphenylchloroethylene on vascular endothelial growth factor and insulin-like growth factor in human and rat ovarian cells

1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE, DDE), a metabolite of DDT is a persistent hormonally active environmental toxicant present in human serum and follicular fluid. The objective of this study was to investigate the effects of DDE on the expression of the ovarian vascular endothelial growth factor (VEGF) and insulin-like growth factor (IGF-1) in primary cultures of human granulosa cells and in the rat ovary. Granulosa cells were obtained at the time of oocyte retrieval for in vitro fertilization and cultured with environmentally relevant concentrations of DDE. Immature female rats were treated with 100 microg DDE/kg body weight or vehicle at 28 and 31 days of age and then euthanized at 50 days of age for collection of ovarian tissue. Expression of VEGF, the VEGF receptor fetal liver kinase (Flk-1) and IGF-1 were determined by Western blotting analysis of protein lysates from granulosa cell cultures and by immunohistochemistry in the rat ovary. DDE at concentrations of 100-1000 ng/mL increased the expression of VEGF, Flk-1 and IGF-1 in vitro in primary cultures of human granulosa cells, with the highest expression occurring at 1000 ng/mL. Similarly, acute administration of DDE resulted in a significant increase in immunoreactive VEGF, Flk-1 and IGF-1 in the rat ovary. We conclude that DDE, at levels, which have been detected in humans, alters the expression of the ovarian growth factors VEGF and IGF-1 both in vivo and in vitro. This alteration in expression of growth factors may lead to altered ovarian function as seen in polycystic ovaries and impaired fertility.