The action of low- and high-chlorinated biphenyl mixture on prepubertal porcine ovary: steroid secretion and cells apoptosis.

To compare the effects on ovarian function of low chlorinated polychlorinated biphenyls (PCBs) mixture generally distributed at a faster rate and metabolised to a greater extent (Delor 103) with high chlorinated PCBs mixture which are accumulated in large amounts in biological samples (Delor 106). Theca interna and granulosa cells were isolated from prepubertal porcine follicles and initially cultured in M199/CS without test compounds for 24 hrs to allow for cell attachment to the wells. After 24 h, the medium was discarded and 0.3 ml of fresh M199 alone was added to the control culture, while Delor 103 or Delor 106 at concentrations of 0.02, 0.2 or 2 ng/ml medium were added to the cultures. For analysis of steroid levels, the media were collected after 24 hrs (single exposure) or 72 hrs (repeated exposure) and frozen at--20 degrees C. Additionally, after 72 hrs, LDL test was used to show the action of both mixtures on the cell viability and cells were used for the measurement of caspase-3 activity. An increase in testosterone secretion after the single exposure and strong stimulatory action on estradiol secretion was noted after permanent treatment with Delor 103. In Delor 106 treated cultures, antiestrogenic action after the single exposure and strong estrogenic action in permanently treated cells was observed. Both mixtures had no effect on cell viability and apoptosis. By stimulation of estradiol secretion from ovarian follicles in prepubertal animals, PCB mixture could be responsible for premature development of follicles and in consequence, premature sexual maturation.