Printed in U.S.A. Copyright © 1998 by The Endocrine Society Dioxin Perturbs, in a Dose- and Time-Dependent Fashion, Steroid Secretion, and Induces Apoptosis

Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin; TCDD) is the most toxic congener of a large class of environmental pollutants. Several studies have shown that TCDD exposure reduced fecundity and ovulatory rate in rats and increased the incidence of endometriosis in monkeys. Recent work suggests that TCDD’s endocrine-disrupting effects are, at least in part, caused by a direct action at the ovary. Although the factors involved in TCDD-induced toxicity are still under investigation, several studies have shown that TCDD induces programmed cell death, or apoptosis, in various tissues and may act in a similar fashion in the ovary. In the present study, we set out to evaluate the in vitro effects of TCDD on steroid secretion, specifically estradiol-17 � (E 2) and progesterone, by human luteinized granulosa cells (LGC), and to further determine whether TCDD is capable of inducing apoptosis in this cell type. Human LGC were obtained from