The effect of an anti-progestin compound (RU486) on gonadotropin release from rat anterior pituitary cells in vitro.

Abstract

AbstractAnterior pituitary cells from castrated female rats were cultured in a medium with or without progesterone (P4), estradiol‐17 β (E2), 17 β‐hydroxy‐11 β‐(4‐dimethylaminophenyl)‐17‐(prop‐1‐ynyl)‐estra‐4,9‐dien‐3‐one (RU486) or norethisterone (NE). Three days later, the media were changed and the cells were incubated further with or without luteinizing hormone releasing hormone (LHRH) (10‐6‐10‐12 M) for 3 hours. LH and FSH released in the media were measured by radioimmunoassay (RIA).At a high concentration of LHRH (>10‐8 M), E2 (10‐9 M) increased the release of LH and FSH significantly. When P4 (10‐6 M) was combined with E2 for 3 days, the release of LH and FSH by E2 was inhibited.RU486 had no direct effect on LH and FSH release. However, the effect of P4 against E2, as mentioned above, was nullified by 10‐6 M of RU486.In the same experimental model, RU486 also inhibited the effect of norethisterone.By the use of the anti‐progestin compound, RU486, it was confirmed that progestins directly inhibited the action of E2 at the anterior pituitary level.