dinoprost and lilopristone

The inhibition of prostaglandin (PG) synthesis found in early human decidua is antagonized by the anti-progestin, ZK 98734. This action of ZK 98734 is abolished by actinomycin, an inhibitor of protein synthesis and by the calcium channel blocker, verapamil. Calmidazolium, an antagonist of the intracellular calcium binding protein calmodulin was less effective in inhibiting the stimulation of PG synthesis induced by the anti-progestin. Chronic stimulation of protein kinase C activity by 1-oleoyl-2-acetyl-sn-glycerol (OAG) induced a slight reduction of PG release and was antagonized by polymixin. These findings suggest that inhibition of PG synthesis in early pregnancy is caused by progesterone and that increased release of PGs induced by anti-progestins is dependent on new protein formation and requires extracellular calcium.

Topics: Abortion, Spontaneous; Calmodulin; Cells, Cultured; Dactinomycin; Decidua; Diglycerides; Dinoprost; Estrenes; Female; Humans; Imidazoles; Kinetics; Pregnancy; Progesterone; Progestins; Radioimmunoassay; Verapamil

Enriched preparations of glandular and stromal cells were obtained from early human decidua and incubated for 24 h in the presence of two progesterone antagonists, RU 486 (17 beta-hydroxy-11 beta-[4-dimethylaminophenyl]17 alpha-[1-propynyl]-estra-4,9-dien-3-one) and ZK 98734 (17 beta-hydroxy-11 beta-4[4-dimethylaminophenyl]17 alpha-[3-hydroxy-1-propynyl]estra-4,9-dien-3-one) to determine the effect of the antiprogestins on the release of prostaglandin F2 alpha (PGF2 alpha) and PGE2 and their subsequent conversion to 15-keto-13,14-dihydro-PGF2 alpha and 15-keto-13,14-dihydro-PGE2. In the presence of exogenous arachidonic acid (AA, 30 microM), both steroids stimulated PGF2 alpha release by glandular, but not stromal, cells (P less than 0.001) and inhibited the metabolism of PGF2 alpha by the glandular fraction (P less than 0.005 and P less than 0.001 respectively). In the absence of exogenous AA, RU 486 and ZK 98734 stimulated the release of PGF2 alpha from glandular, but not stromal, cells (P less than 0.001 and P less than 0.005, respectively). Neither steroid altered the release or metabolism of PGE2 when the cells were incubated with AA, but both RU 486 and ZK 98734 increased the release of PGE2 by glandular, but not stromal, cells when incubated without AA (P less than 0.005 and P less than 0.001, respectively). Both steroids inhibited the metabolism of PGE2 under these conditions (P less than 0.05). These results suggest that 1) antiprogestins stimulate the synthesis of PGs by glandular cells in early human decidua, but do not alter the synthesis of PGs by stromal cells; 2) this stimulation of PG synthesis involves an effect on cyclooxygenase activity and is not a consequence of increased availability of endogenous AA; 3) the metabolism of PGs by glandular cells is altered by RU 486 and ZK 98734; 4) as RU 486 has greater antiglucocorticoid activity than ZK 98734, these results suggest that both steroids act on decidua by antagonizing endogenous progesterone rather than glucocorticoid activity.

Topics: Cells, Cultured; Decidua; Dinoprost; Dinoprostone; Estrenes; Female; Humans; Mifepristone; Pregnancy; Progestins; Prostaglandins E; Prostaglandins F

Three antiprogestogens of the RU 38.486, ZK 98.734, and ZK 98.299, were studied at different stages of pregnancy in the guinea pig. Treatment starting on postconception day 4 completely prevented nidation; all three compounds had comparable inhibitory potency. Treatment after nidation, starting on postconception day 8, induced decidual collapse and bleeding, but embryonic tissue was retained in nidation sites. In contrast to results in animals in nonfertile cycles, luteolysis was not induced, indicating that antiprogestogens lack the ability to induce uterine prostaglandin synthesis/liberation. On postconception day 43, RU 38.486 showed marginal abortifacient activity. The other compounds induced expulsion more rapidly and at a higher rate. The comparatively pronounced antiglucocorticoid activity of RU 38.486 may account for this difference. With RU 38.486, a high level of uterine prostaglandin sensitivity and a cervical ripening were induced consistently and fast; spontaneous labor, on the other hand, occurred after several days, if at all. Complete uterine evacuation was induced within hours by otherwise inactive doses of sulprostone in various combinations with ZK 98.299 RU 38.486 but surprisingly not with ZK 98.734. A single dose of ZK 98.299 induced an approximately thirtyfold increase in uterine prostaglandin sensitivity within 24 hours, exceeding that present before term, but did not induce spontaneous labor. This is evidence that endogenous prostaglandins were not activated, analogous to perinidation stages. Observation of antiluteolytic activity of antiprogestogens in nonpregnant animals is considered of major theoretical importance in this context. It seems that inhibition of progesterone leads to suppressed uterine prostaglandin liberation. The same effect in pregnancy could explain the inability of the uterus to expel a seriously compromised conceptus. In conclusion, we suggest that progesterone is a stimulator rather than a depressor of uterine prostaglandins in the late luteal phase and pregnancy. The ability of the conceptus to neutralize this stimulatory action of progesterone is considered to be essential for the rescue of the corpus luteum and uterine motor quiescence in the guinea pig. The clinical significance of these findings is that the high frequency of incomplete abortions and protracted, sometimes heavy bleeding in pregnant women treated with RU 38.486 may reflect decidual compromise and simultaneous uterine prostaglandin deficie

Topics: Abortion, Induced; Animals; Dinoprost; Dinoprostone; Dose-Response Relationship, Drug; Embryo Implantation; Endometrium; Estrenes; Female; Gonanes; Guinea Pigs; Mifepristone; Myometrium; Pregnancy; Pregnancy, Animal; Progesterone; Prostaglandins E, Synthetic; Prostaglandins F; Uterine Contraction

The mechanism by which progesterone inhibits PG production is not clear. In systems using isolated human endometrial fragments, progesterone has been shown to inhibit PG production markedly. We have used such a system to test the action of two antiprogesterone steroids RU486 (Roussell-Uclaf) and ZK98734 (Schering) on isolated human endometrial and decidual tissue, with and without added progesterone. Progesterone (200 nM) reduced PGF2 alpha production by the secretory phase endometrium from 10.9 ng/mg tissue/24 hr to 1.9 ng/mg/24hr on the third day of culture (p less than .01) and this effect was antagonised by the addition of either 200 nM RU486 or 200 nM ZK98734 (6.3 and 7.2 ng/mg/24 hr respectively). The antiprogestins on their own showed a slight inhibitory effect on day 3 and RU486 treatment resulted in a significant (p less than .05) decrease in PG production from control. PGE and the main 13,14-dihydro-15-keto metabolites of E and F were also significantly decreased by progesterone and restored by the antiprogestins. The PG production by decidua increased on days 2 and 3 in response to progesterone + antiprogestins but this was not significant. This data shows that the inhibition of PG production shown by progesterone, acting on secretory phase endometrium cultured as tissue fragments, is reversible by the receptor blocking antiprogestins.

Topics: Adult; Decidua; Dinoprost; Endometrium; Estrenes; Female; Humans; Mifepristone; Progesterone; Progestins; Prostaglandins; Prostaglandins F

Endometrial stromal cells and isolated endometrial glands obtained from women during days 6-26 of the ovarian cycle were cultured for 24 h in the presence of the progesterone antagonists 17 beta-hydroxy-11 beta-[4-dimethylaminophenyl]17 alpha-[1-propynyl] estra-4,9-dien-3-one (RU486) and 17 beta-hydroxy-11 beta-[4-dimethylaminophenyl] 17 alpha-[3-hydroxy-1-propenyl]estra-4,9-dien-3-one (ZK 98734). Both steroids stimulated prostaglandin F2 alpha (PGF2 alpha) production by stromal cells in a dose-dependent manner, in doses ranging from 10-1000 nM. Progesterone (100 nM) inhibited RU486 stimulation, except at the highest dose of antiprogestin. PGE2 was produced in smaller amounts than PGF2 alpha, but, when measurable, it also increased in the presence of RU486. In contrast, RU486 did not increase PG production by endometrial glands. In an experiment to determine the effect of pretreatment, stromal cells were incubated for 24 h with 1000 nM progesterone or RU486 (all with 100 nM 17 beta-estradiol) with either 30 or 6 microM arachidonic acid. These six batches of cells were incubated for a second 24 h with either progesterone or antiprogestin. Cells pretreated with the higher dose of arachidonic acid had a marked increase in PGF2 alpha production during the second 24 h only when also pretreated with progesterone. This finding suggests that progesterone allows an accumulation of PG precursor in a suitable accessible pool. Pretreatment with progesterone also allowed a greater conversion of PG to its 13,14-dihydro-15-keto metabolite. These results suggest that antiprogesterone steroids may act as menstrual regulators by: stimulating endogenous PG production within the endometrial stromal cells and inhibiting PG catabolism.

Topics: Dinoprost; Dinoprostone; Endometrium; Estrenes; Fatty Acids; Female; Humans; In Vitro Techniques; Mifepristone; Progesterone; Prostaglandins; Prostaglandins E; Prostaglandins F