The effect of estradiol-17β and actinomycin D on the release of PGF and PGE from separated cells of human endometrium

Estradiol-17β selestively stimulated the release of PGF from separated glandular but not stromal cells of human secretory endometrium (p<0.025) but had no effect on PGF release from either type of cells obtained from proliferative endometrium. PGE release was not affected by estradiol-17β. Actinomycin D did not antagonise the effect of estradiol-17β on PGF release from secretory, glandular cells. Basal release of PGF from these cells was stimulated by actinomycin D alone (100 ng/ml) (p<0.025) and PGE release stimulated in the presence of estradiol-17β. Actinomycin D had no effect on PGF or PGE release from proliferative endometrium. These findings suggest that estradiol-17β stimulates PGF release by a mechanism that does not affect PGE release and which is not dependent on the synthesis of new protein. The basal release of PGF and PGE by glandular cells of secretory endometrium in vitro is regulated by protein/proteins which reduce PG release.     

The release of PGF2 alpha and PGE2 from separated cells of human endometrium and decidua

The capacity of separated glandular and stromal cells from endometrium and first trimester decidua to release prostaglandins (PGs) was studied over 48 hours in culture. Glandular preparations released more PGs than stromal preparations in all tissues. Stromal release of PGs did not alter throughout the cycle or in early pregnancy but the capacity of glandular preparations to release PGs varied considerably. Proliferative glands released most PGF2 alpha and PGE2 followed by secretory glands and decidua. Histamine (10(-5)) stimulated PG release from endometrial and decidual glands but the response of proliferative glands was greatest. Actinomycin D stimulated release of PGF2 alpha and PGE2 from glandular cells of secretory endometrium and decidua. These results suggest that in vitro release of PGs is suppressed after ovulation and is in part due to inhibition of PG release by a protein or proteins synthesized in the glandular fraction of secretory endometrium or decidua.     

Prostaglandin E and E2 alpha secretion by glandular and stromal cells of the pig endometrium in vitro: effects of estradiol-17 beta, progesterone, and day of pregnancy.

Prostaglandins (PGs) are believed to play important roles in the establishment of pregnancy. Glandular and stromal cells were isolated from pig endometrium on days 11 through 19 of pregnancy and cultured in the presence of estradiol-17 beta (E2) and progesterone (P4) to determine the effect of day of pregnancy and steroids on the secretion of PGE and PGF2 alpha. Estradiol at concentrations between .01 and 1 microM did not affect PGE and PGF2 alpha secretion into the medium by glandular and stromal cells. Progesterone (.1 microM) suppressed (P less than .001) PGE and PGF2 alpha production from both cell types. Glandular cells secreted more (P less than .01) PGF2 alpha than PGE, whereas stromal cells collected on days 11, 12, 13, and 19 secreted more (P less than .05) PGE than PGF2 alpha. Stromal cells isolated from tissues collected on day 13 of pregnancy produced PGs with higher (P less than .01) PGE:PGF2 alpha ratio than those from tissues harvested on other days of pregnancy. Glandular cells isolated from tissues collected on days 13 and 19 and stromal cells isolated from tissue collected on day 13 of pregnancy secreted more (P less than .05) PGE and PGF2 alpha than cells isolated on other days of pregnancy. We conclude that: 1) P4 has a suppressing effect on PG secretion; 2) endometrial glandular and stromal cells each produce a unique profile of PGs; and 3) endometrial cells harvested on different days of pregnancy secrete different amounts of PGE and PGF2 alpha.     

The effect of cortisol on the synthesis of prostaglandins (PGF2 alpha, PGE2) by human endometrial fibroblasts in vitro with and without addition of estradiol-17 beta or progesterone

Cortisol is known as a potent inhibitor of phospholipase A2 activity in several tissues. In fibroblast monolayer cell cultures from proliferative human endometrium cortisol alone does not affect the basal PGF2 alpha or PGE2 synthesis. After stimulation of PGF2 alpha production by 10(-7) mol/l estradiol-17 beta increasing concentrations of cortisol up to 10(-5) mol/l dosedependently reduce the PGF2 alpha production. Also the progesterone (10(-4) mol/l) stimulated increase of PGF2 alpha and PGE2 synthesis is inhibited by cortisol (10(-7) mol/l).     

Effect of porcine conceptus secretory proteins on in vitro secretion of prostaglandins-F2 alpha and -E2 from luminal and myometrial surfaces of endometrium from cyclic and pseudopregnant gilts

Uterine endometrium collected from pseudopregnant (PP) and cyclic gilts on day (D) 15 after estrus were perifused in vitro with 10 ug/ml of porcine conceptus secretory proteins (pCSP) or serum proteins (SP) in Krebs ringer bicarbonate (KRB) buffer. In Experiment 1, samples were collected from luminal and myometrial surfaces of endometrium and concentrations of prostaglandin F2 alpha (PGF) determined by radioimmunoassay (RIA). Secretion of PGF by endometrium from cyclic gilts was stimulated (P less than .05) by pCSP. In Experiment 2, endometrium from D 14 cyclic and PP gilts was perifused and concentrations of PGF and prostaglandin E2 (PGE) in perfusate were determined by RIA. Across both statuses, luminal surface secretion of PGF was stimulated (P less than .05) by pCSP. Treatment with pCSP decreased secretion of PGE from myometrial surface of endometrium from cyclic gilts and increased (P less than .01) secretion of PGE from the myometrial surface of endometrium from PP gilts. In Experiment 3, pCSP were separated into acidic and basic fractions by anion exchange chromatography and each fraction was perifused separately over the luminal surface of endometrium from cyclic and PP gilts. Perifusion with acidic pCSP suppressed secretion of PGF by endometrium from cyclic or PP gilts; while basic pCSP did not influence secretion of PGF. These results demonstrated that products secreted by Day 15 pig conceptuses stimulate release of PGF and PGE from porcine uterine endometrium.     

Endothelin-1 stimulates prostaglandin F2 alpha release from human endometrium

Despite a key role in the pathogenesis of menorrhagia, the factors controlling the uterine vascular bed are poorly understood. This study has assessed the effects of the potent vasoconstrictor endothelin (ET)-1 on prostaglandin (PG) release from human endometrial explants in short-term culture. There was no significant difference between the production of PGF2 alpha in proliferative and secretory tissue (1709 and 2434 pg/mg/h--median values, range 70,3745 and 219,6700 pg/mg/h). Less PGE was released than PGF2 alpha, and the amount did not vary with the phase of the menstrual cycle (308 and 296 pg/mg/h (range 65,387 and 105,429) for proliferative and secretory tissue). ET-1 (10 and 100 nM) and arachidonic acid (AA, 30 microM), stimulated PGF2 alpha release from proliferative, but not secretory endometrium, by 78%, 86% (P less than 0.01) and 80% respectively, compared with control tissue. No effect was seen on PGE release. ET-1 may play a role in the local control of the endometrial vascular bed either directly, or via the release of PGF2 alpha.     

Cell-type specific responses in prostaglandin secretion by glandular and stromal cells from pig endometrium treated with catecholestrogens, methoxyestrogens and progesterone.

The pig conceptus and endometrium possess the ability to convert estrogens into catecholestrogens and catecholestrogens into methoxyestrogens. Experiments were carried out to evaluate the effect of catecholestrogens, methoxyestrogens and progesterone on the secretion of prostaglandin (PG) E and F2 alpha by porcine endometrial glandular and stromal cells in vitro. Both 2-hydroxyestradiol (2-OH-E2, 0-20 microM) and 4-hydroxyestradiol (4-OH-E2, 0-20 microM) increased (P less than .05) PGE and PGF2 alpha secretion by stromal cells in a dose response manner. Two-hydroxyestradiol tended (P less than .1) to decrease PGF2 alpha production by glandular cells. Two-methoxyestradiol (20 microM) suppressed (P less than .05) PGF2 alpha secretion by glandular and stromal cells. Four-methoxyestradiol (20 microM) stimulated (P less than .05) PGE production and PGE:PGF2 alpha ratio. Progesterone (.1 microM) suppressed (P less than .05) PG secretion in both cell types. We conclude that catecholestrogens, methoxyestrogens, and progesterone may participate in the establishment of pregnancy by modulating PG production in the endometrium.     

What regulates placental steroidogenesis in 90-day pregnant ewes?

By day-90, the placenta secretes half of the circulating progesterone and 85% of the circulating estradiol-17beta [Weems YS, Vincent D, Tanaka Y, et al. Effects of prostaglandin F(2alpha) on sources of progesterone and pregnancy in intact, ovariectomized, and hysterectomized 90-100 day pregnant ewes. Prostaglandins 1992;43:203-22; Weems YS, Vincent DL, Nusser K, et al. Effects of prostaglandin F(2alpha) (PGF(2alpha)) on secretion of estradiol-17beta and cortisol in 90-100 day hysterectomized, intact, or ovariectomized pregnant ewes. Prostaglandins 1994;48:139-57]. Ovariectomy (OVX) or prostaglandin (PG) F(2alpha) (PGF(2alpha)) does not abort intact or OVX 90-day pregnant ewes and PGF(2alpha) regresses the corpus luteum, but does not affect placental progesterone secretion in vivo [Weems YS, Vincent D, Tanaka Y, et al. Effects of prostaglandin F(2alpha) on sources of progesterone and pregnancy in intact, ovariectomized, and hysterectomized 90-100 day pregnant ewes. Prostaglandins 1992;43:203-22]. Luteal progesterone secretion in vitro at day-90 of pregnancy in ewes is regulated by PGE(1)and/or PGE(2), not by ovine luteinizing hormone (LH; 3). Concentrations of PGE in uterine or ovarian venous plasma averaged 6 ng/ml at 90-100 days of pregnancy in ewes [Weems YS, Vincent DL, Tanaka Y, Nusser K, Ledgerwood KS, Weems CW. Effect of prostaglandin F(2alpha) on uterine or ovarian secretion of prostaglandins E and F(2alpha) (PGE; PGF(2alpha)) in vivo in 90-100 day hysterectomized, intact or ovariectomized pregnant ewes. Prostaglandins. 1993;46:277-96]. Ovine placental PGE secretion is regulated by LH up to day-50 and by pregnancy specific protein B (PSPB) after day-50 of pregnancy [Weems YS, Kim L, Humphreys V, Tsuda V, Weems CW. Effect of luteinizing hormone (LH), pregnancy specific protein B (PSPB), or arachidonic acid (AA) on ovine endometrium of the estrous cycle or placental secretion of prostaglandins E(2) (PGE(2)) and F(2alpha) (PGF(2alpha)), and progesterone in vitro. Prostaglandins Other Lipid Mediators 2003;71:55-73]. Indomethacin (INDO), a prostaglandin synthesis inhibitor [Lands WEM. The biosynthesis and metabolism of prostaglandins. Annu Rev Physiol 1979;41:633-46], lowers jugular venous progesterone [Bridges PJ, Weems YS, Kim L, et al. Effect of prostaglandin F(2alpha) (PGF(2alpha)), indomethacin, tamoxifen or estradiol-17beta on pregnancy, progesterone and pregnancy specific protein B (PSPB) secretion in 88-90 day pregnant ewes. Prostaglandins Other Lipid Mediators 1999;58:113-24] and inferior vena cava PGE of pregnant ewes with ovaries by half at day-90 [Bridges PJ, Weems YS, Kim L, LeaMaster BR, Vincent DL, Weems CW. Effect of prostaglandin F(2alpha) (PGF(2alpha)), indomethacin, tamoxifen or estradiol-17beta on prostaglandin E (PGE), PGF(2alpha) and estradiol-17beta secretion in 88-90 day pregnant sheep. Prostaglandins Other Lipid Mediators 1999;58:167-78]. In addition, treatment of 90 day ovine diced placental slices with androstenedione in vitro increased placental estradiol-17beta, but treatment with PGF(2alpha)in vitro did not decrease placental progesterone secretion, which indicates that ovine placenta progesterone secretion is resistant to the luteolytic action of PGF(2alpha) [Weems YS, Bridges PJ, LeaMaster BR, Sasser RG, Vincent DL, Weems CW. Secretion of progesterone, estradiol-17beta, prostaglandins (PG) E (PGE), F(2alpha) (PGF(2alpha)), and pregnancy specific protein B (PSPB) by day 90 intact or ovariectomized pregnant ewes. Prostaglandins Other Lipid Mediators 1999;58:139-48]. This also explains why ovine uterine secretion of decreased around day-50 [Weems YS, Kim L, Humphreys V, Tsuda V, Weems CW. Effect of luteinizing hormone (LH), pregnancy specific protein B (PSPB), or arachidonic acid (AA) on ovine endometrium of the estrous cycle or placental secretion of prostaglandins E(2) (PGE(2)) and F(2alpha) (PGF(2alpha)), and progesterone in vitro. Prostaglandins Other Lipid Mediators 2003;71:55-73], when placental estradiol-17beta secretion is increasing [Weems C, Weems Y, Vincent D. Maternal recognition of pregnancy and maintenance of gestation in sheep. In: Reproduction and animal breeding: advances and strategies. Enne G, Greppi G, Lauria A, editors, Elsevier Pub., Amsterdam 1995. p. 277-93]. Treatment of 90 day pregnant ewes with estradiol-17beta+ PGF(2alpha), but not either treatment alone, caused a linear increase in both estradiol-17beta and PGF(2alpha) and ewes were aborting [Bridges PJ, Weems YS, Kim L, Sasser RG, LeaMaster BR, Vincent DL, Weems CW. Effect of prostaglandin F(2alpha) (PGF(2alpha)), indomethacin, tamoxifen or estradiol-17beta on pregnancy, progesterone and pregnancy specific protein B (PSPB) secretion in 88-90 day pregnant ewes. Prostaglandins Other Lipid Mediators 1999;58:113-24; Bridges PJ, Weems YS, Kim L, LeaMaster BR, Vincent DL, Weems CW. Effect of prostaglandin F(2alpha) (PGF(2alpha)), indomethacin, tamoxifen or estradiol-17beta on prostaglandin E (PGE), PGF(2alpha) and estradiol-17beta secretion in 88-90 day pregnant sheep. Prostaglandins Other Lipid Mediators 1999;58:167-78]. Pregnant ewes OVX on day 83 of pregnancy and placental slices cultured in vitro secretes 2-3-fold more estradiol-17beta, PSPB, PGE, and progesterone than placental slices from 90 day intact pregnant ewes, but placental PGF(2alpha) secretion by placental slices from intact or OVX ewes did not change [Denamur R, Kann G, Short R V. How does the corpus luteum of the sheep know that there is an embryo in the uterus? In: Pierrepont G, editor. Endocrinology of pregnancy and parturition, vol. 2. Cardiff, Wales, UK: Alpha Omega Pub Co.; 1973. p. 4-38]. The objective of these experiments was to determine what regulates ovine placental progesterone and estradiol-17beta secretion at day-90 of pregnancy, since the hypophysis [Casida LE, Warwick J. The necessity of the corpus luteum for maintenance of pregnancy in the ewe. J Anim Sci 1945;4:34-9] or ovaries [Weems CW, Weems YS, Randel RD. Prostaglandins and reproduction in female farm animals. Vet J 2006;171:206-28] are not necessary after day-55 to maintain pregnancy. In Experiment 1, diced placental slices from day-90 intact or OVX pregnant ewes that were ovariectomized or laparotomized and ovaries were not removed on day 83 were collected on day-90 and incubated in vitro in M-199 with Vehicle, ovine luteinizing hormone (oLH), ovine follicle stimulating hormone (oFSH), ovine placental lactogen (oPL), PGE(l), PGE(2), PGD(2), PGI(2), insulin-like growth factor (IGF) 1 or 2 (IGF(l); IGF(2)), leukotriene C(4) (LTC(4)), platelet activating factor (PAF) 16 or 18 (PAF-16; PAF-18) at doses of 0, 1, 10, or 100ng/ml for 4h. In Experiment 2, placental slices from day-90 intact and OVX (intact or OVX laporotomized 7 days earlier) pregnant ewes were incubated in vitro with vehicle, INDO, Meclofenamate (MECLO), PGE(l), PGE(2), INDO+PGE(1), MECLO+PGE(l), INDO+PGE(2), or MECLO+PGE(2) for 4h. Media were analyzed for progesterone, estradiol-17beta, PGE, or PGF(2alpha) by RIA. Hormone data in media were analyzed in Experiment 1 by a 2x3x13 and in Experiment 2 by a 2x9 Factorial Design for ANOVA. In Experiment 1, placental progesterone, PGE, or estradiol-17beta secretion were increased (P< or =0.05) two-fold by OVX. Progesterone was not increased (P> or =0.05) by any treatment other than OVX and only FSH increased (P< or =0.05) estradiol-17beta secretion by placental slices in both OVX and intact ewes 90-day pregnant ewes. In Experiment 2, INDO or MECLO decreased (P< or =0.05) placental progesterone secretion by 88% but did not decrease (P> or =0.05) placental estradiol-17beta secretion from intact or OVX ewes. PGE(l) or PGE(2) increased (P< or =0.05) progesterone secretion only in ewes treated with INDO or MECLO. It is concluded that FSH probably regulates day-90 ovine placental estradiol-17beta secretion, while PGE(l) or PGE(2) regulates day-90 placental progesterone secretion.     

PGE2 induces its own secretion in vitro by bovine 270-day placenta but not by 200-day placenta.

Two separate experiments were conducted to determine whether prostaglandin (PG) E2 stimulates the secretion of progesterone by 270- or 200-day Brahman placentas in vitro. Secretion of progesterone, PGF2alpha, pregnancy specific protein B, or estradiol-17beta by 270-day Brahman placentas was not affected (p > or = 0.05) by PGE2, during the 4-h incubation period at the doses tested. Indomethacin or meclofenamic acid decreased (p < or = 0.05) 270-day Brahman placental secretion of PGE and PGF2alpha by 98 and 60%, respectively. However, PGE2 induced (p < or = 0.05) its own secretion, but not the secretion of PGF2alpha (p > or = 0.05), by 270-day Brahman placentas, even in the presence of indomethacin or meclofenamic acid at a dose of 100 ng/mL. Also, secretion of 8-Epi-PGE2 by Day 270 Brahman placentas was increased (p < or = 0.05) by PGE2. Secretion of progesterone, estradiol-17beta, or pregnancy specific protein B by 200-day Brahman placentas was not affected by PGE2, 8-Epi-PGE2, PGF2alpha, estradiol-17beta, or trichosanthin during the 4- or 8-h incubation period (p > or = 0.05). Secretion of estradiol-17beta at 8 h was lower (p < or = 0.05) in all treatment groups and did not differ (p > or = 0.05) among the 8-h incubation treatment groups. Secretion of PGE by 200-day Brahman placentas was reduced (p < 0.05) by indomethacin 72 and 82% and by meclofenamic acid 72 and 96%, respectively, at 4 and 8 h when compared to controls. Secretion of PGF2alpha was reduced (p < or = 0.05) 71 and 86% by indomethacin or 89 and 89% by meclofenamic acid at 4 and 8 h, respectively, and did not differ (p > or = 0.05) between 4 and 8 h of incubation. PGE2 did not (p > or = 0.05) induce secretion of PGE above what was added in any treatment group. PGE in culture media was increased (p < or = 0.05) by 8-Epi-PGE2, pregnancy specific protein B, and the 100 ng/mL PGF2alpha dose (p < or = 0.05), but not by PGE2, progesterone, estradiol-17beta, 8-Epi-PGF2alpha, or trichosanthin. Secretion of PGF2alpha by 200-day Brahman placentas was not affected (p > or = 0.05) by 8-Epi-PGE2, progesterone, or estradiol-17beta, but PGF2alpha secretion was increased (p < or = 0.05) by trichosanthin or PGE2, even in the presence of indomethacin or meclofenamic acid. It is concluded that PGE does not affect secretion of progesterone by 200- or 270-day bovine placentas, but, pregnancy specific protein B may regulate placental secretion of PGE. Also, indomethacin and meclofenamic may affect enzymes converting PGH to PGE rather than acting only on cyclooxygenase because indomethacin and meclofenamic acid lowered PGE secretion by 270-day Brahman placentas more than they lowered PGF2alpha. In addition, it is concluded that PGE2 can induce bovine placental secretion of PGE, but this is dependent upon the stage of gestation.     

Effects of 17 beta-estradiol and progesterone on the levels of prostaglandins F2 alpha and E in human endometrium

17 beta-estradiol and progesterone were administered to post-menopausal women to determine their effects in vivo on the capacity of human endometrium to synthesize prostaglandins (PGs) F2 alpha and E. Basal amounts of PGF2 alpha and PGE synthesized by endometrium exposed to 17 beta-estradiol and progesterone were significantly higher than the levels produced by endometrium exposed to 17 beta-estradiol alone (p less than 0.02 for both PGs). Levels found in the former endometrium were broadly comparable to levels in secretory endometrium and in the latter to amounts found in proliferative endometrium of spontaneous, ovulatory cycles.     

The effect of progesterone and human interferon alpha-2 on the release of PGF2 alpha and PGE from epithelial cells of human proliferative endometrium.

Progesterone and interferon-like trophoblastic proteins modulate prostaglandin (PG) synthesis from endometrium in early ovine and bovine pregnancy. Enriched epithelial cells were prepared from human endometrium removed in the proliferative phase of menstrual cycle (n = 8). Progesterone at a concentration of 1 microM suppressed PGE release from the cells during the first 24 hours in culture. After 48 hours in culture progesterone at a dose of 100 nM and 1 microM suppressed both the release of PGF2 alpha and PGE from the cells and this suppression was maintained for a further two days. Addition of exogenous 30 microM arachidonic acid (AA) abolished this effect of progesterone on both PGF2 alpha and PGE release. Interferon alpha-2 did not suppress the basal release of PGF2 alpha nor PGE. In the presence of progesterone, interferon alpha-2 attenuated the progesterone mediated suppression of PGF2 alpha but not PGE release from endometrial cells. These findings suggest that progesterone suppresses the basal release of PGs from human endometrium, but unlike the sheep, interferon alpha-2 does not exert this action on human endometrium.     

Oxytocin-stimulated production of prostaglandin F2alpha by isolated endometrium of rabbit: modulation by ovarian steroids

To test the hypothesis that ovarian steroid hormones modulate oxytocin-induced release of prostaglandin F2alpha (PGF2alpha) from uterine endometrium, 2 ovariectomized rabbits were pretreated with progesterone (5 mg/day for 10 days), 2 with estradiol-17 beta (25 microgram/day for 10 days), 2 with both steroids, and one with sesame oil only. On the last day of treatment, endometrial fragments were excised and incubated in vitro with or without oxytocin (100 muU/ml). Although endometrium from rabbits pretreated with combined steroids released more PGF2alpha immediately after excision than did tissue from animals pretreated with either steroid by itself, endometrium from animals pretreated with estradiol-17 beta alone released the most PGF2alpha during sustained incubation in vitro. Moreover, only this tissue exhibited significant oxytocin-dependent release of PGF2alpha. At the dosages used, progesterone completely antagonized both of these effects of estradiol-17 beta. The results support the hypothesis that ovarian steroid hormones regulate oxytocin-dependent release of PGF2alpha from endometrial cells. A posible mechanism of action is suggested.     

Phytoestrogens modulate prostaglandin production in bovine endometrium: cell type specificity and intracellular mechanisms

Prostaglandins (PGs) are known to modulate the proper cyclicity of bovine reproductive organs. The main luteolytic agent in ruminants is PGF2alpha, whereas PGE2 has luteotropic actions. Estradiol 17beta (E2) regulates uterus function by influencing PG synthesis. Phytoestrogens structurally resemble E2 and possess estrogenic activity; therefore, they may mimic the effects of E2 on PG synthesis and influence the reproductive system. Using a cell-culture system of bovine epithelial and stromal cells, we determined cell-specific effects of phytoestrogens (i.e., daidzein, genistein), their metabolites (i.e., equol and para-ethyl-phenol, respectively), and E2 on PGF2alpha and PGE2 synthesis and examined the intracellular mechanisms of their actions. Both PGs produced by stromal and epithelial cells were significantly stimulated by phytoestrogens and their metabolites. However, PGF2alpha synthesis by both kinds of cells was greater stimulated than PGE2 synthesis. Moreover, epithelial cells treated with phytoestrogens synthesized more PGF2alpha than stromal cells, increasing the PGF2alpha to PGE2 ratio. The epithelial and stromal cells were preincubated with an estrogen-receptor (ER) antagonist (i.e., ICI), a translation inhibitor (i.e., actinomycin D), a protein kinase A inhibitor (i.e., staurosporin), and a phospholipase C inhibitor (i.e., U73122) for 0.5 hrs and then stimulated with equol, para-ethyl-phenol, or E2. Although the action of E2 on PGF2alpha synthesis was blocked by all reagents, the stimulatory effect of phytoestrogens was blocked only by ICI and actinomycin D in both cell types. Moreover, in contrast to E2 action, phytoestrogens did not cause intracellular calcium mobilization in either epithelial or stromal cells. Phytoestrogens stimulate both PGF2alpha and PGE2 in both cell types of bovine endometrium via an ER-dependent genomic pathway. However, because phytoestrogens preferentially stimulated PGF2alpha synthesis in epithelial cells of bovine endometrium, they may disrupt uterus function by altering the PGF2alpha to PGE2 ratio.     

A possible role of prostaglandin E2 in reproduction of the male water frog, Rana esculenta. In vivo and in vitro studies.

Plasma prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2 alpha), androgens and estradiol-17 beta were measured in the male water frog, Rana esculenta, during the annual sexual cycle. In vivo experiments were carried out to study the effects of PGE2 and PGF2 alpha on plasma sex steroids during the following periods: prereproduction (April), reproduction (May), postreproduction (June) and recovery (October). In the same months, in vitro experiments were performed to evaluate the effects of these two prostaglandins (PGs) on testicular release of sex steroids. The PGE2 plasma levels peaked in April. PGE2 treatment in vivo increased androgens in April and October, while PGF2 alpha increased estradiol-17 beta in June and October. In in vitro experiments, PGE2 increased androgens in April, while PGF2 alpha increased estradiol-17 beta in October. These results suggest that PGE2 could induce the breeding activity, probably through androgens synthesis. PGF2 alpha could interrupt the breeding, through estradiol-17 beta secretion.     

Effect of prostaglandins on in vitro synthesis of progesterone and oestradiol-17 beta in placenta from early human pregnancy

In vitro synthesis of progesterone and estradiol-17 beta from endogenous precursors was studied in the placenta from women in early stage of gestation (less than 7 weeks). Radioimmunoassay techniques were used to measure progesterone and estradiol-17 beta. It was shown that placental tissue from as early as six weeks of gestation can synthesize both progesterone and estradiol-17 beta in vitro. Prostaglandins F2 alpha and E2 in concentration of 100 micrograms/ml of the incubation media did not have any significant effect on the in vitro synthesis of progesterone and estradiol-17 beta in the placental tissue. It seems unlikely that the abortifacient effect of natural prostaglandins PGE2 and PGF2 alpha is due to their direct action on the synthesis of progesterone and estradiol-17 beta in the placenta.     

Effect of prostaglandin F2alpha (PGF2alpha), indomethacin, tamoxifen or estradiol-17beta on prostaglandin E (PGE), PGF2alpha and estradiol-17beta secretion in 88 to 90-day pregnant sheep

Treatment with PGF2alpha plus estradiol-17beta aborts 90-day pregnant ewes, whereas PGF2alpha or estradiol-17beta alone does not abort ewes. The objective of this experiment was to evaluate whether tamoxifen, an estrogen receptor antagonist, estradiol-17beta, prostaglandin F2alpha (PGF2alpha), indomethacin, or some of their interactions affected ovine uterine/placental secretion of PGF2alpha, estradiol-17beta or prostaglandins E (PGE), because a single treatment with PGF2alpha and estradiol-17beta given every 6 h aborts 90-day pregnant ewes. Concentrations of PGF2alpha in uterine venous blood were increased (P < or = 0.05) by estradiol-17beta, PGF2alpha + estradiol-17beta, and PGF2alpha + tamoxifen, and decreased (P < or = 0.05) by indomethacin or PGF2alpha + indomethacin at 72 h when compared to the 0 h samples. Concentrations of PGE in uterine venous blood were decreased (P < or = 0.05) by indomethacin and PGF2alpha + indomethacin and increased (P < or = 0.05) by PGF2alpha + estradiol-17beta at 72 h when compared to the 0 h samples. Concentrations of PGF2alpha in inferior vena cava blood at 6 h were increased (P < or = 0.05) by PGF2alpha either alone or in combination with indomethacin, tamoxifen, or estradiol-17beta, which is due to the PGF2alpha injected. Concentrations of PGF2alpha in inferior vena cava blood in PGF2alpha + estradiol-17beta-treated 88- to 90-day pregnant ewes increased (P < or = 0.05) linearly over the 72-h sampling period and averaged 4.0 + 0.4 ng/ml. Concentrations of PGF2alpha in inferior vena cava blood of control, PGF2alpha, tamoxifen, PGF2alpha + indomethacin, PGF2alpha + tamoxifen, and estradiol-17beta-treated ewes did not differ (P > or = 0.05) and averaged 0.4 + 0.04 ng/ml. Profiles of PGE in inferior vena cava blood of 88- to 90-day pregnant ewes treated with vehicle, PGF2alpha, estradiol-17beta, tamoxifen, tamoxifen + PGF2alpha, or estradiol-17beta + PGF2alpha did not differ (P > or = 0.05). Concentrations of PGE in inferior vena cava blood of 88- to 90-day pregnant ewes treated with indomethacin or PGF2alpha + indomethacin were lower (P < or = 0.05) than in control ewes. Concentrations of estradiol-17beta in jugular venous plasma of PGF2alpha + estradiol-17beta-treated 88- to 90-day pregnant ewes increased linearly and differed (P < or = 0.05) from controls. Profiles of estradiol-17beta in jugular venous plasma of PGF2alpha, indomethacin, tamoxifen, and PGF2alpha + tamoxifen and PGF2alpha + indomethacin, estradiol-17beta, and controls did not differ (P > or = 0.05). It is concluded that treatment with a single injection of PGF2alpha and estradiol-17beta given every 6 h causes a linear increase in PGF2alpha and estradiol-17beta.     

Ultrastructural changes in guinea pig endometrial cells during the estrous cycle.

In the guinea pig, the estrous cycle is characterized by a constant measurable level of plasma progesterone with two peaks: the first one associated with the peak of plasma estradiol-17 beta occurring at proestrus and the second, during diestrus, more pronounced at the time at which the level of estradiol-17 beta is undetectable. The progesterone receptor content is the highest on day 1 and the lowest on day 10 of the estrous cycle, which lasts 16.3 +/- 1.5 days (n = 37; mean +/- SD). There is a positive correlation between the plasma level of estradiol-17 beta and the progesterone receptors detected immunocytochemically in both endometrial epithelial and stromal cells. The general morphology of the endometrium during proestrus and estrus is consistent with an estrogenic stimulation, i.e., a smooth and regular surface of the endometrium and the presence of numerous microvilli on the cell surface. However, a moderate secretory activity also occurs in proestrus and estrus. During postestrus, the glandular cells display an increase in characteristic secretory features which parallels the rise of progesterone in the plasma.     

Synthesis of prostaglandins by pig blastocysts cultured in medium containing estradiol or catechol estrogen.

Two experiments were conducted to determine the effects of 2-hydroxy-estradiol-17 beta (2-OH-E2; 0, 50 and 100 microM) and estradiol-17 beta (E2; 0, 25 and 50 microM) on prostaglandin (PG) E and PGF2 alpha synthesis by day-10 pig blastocysts (day 0 is first day of estrus). Blastocysts were incubated in a modified Krebs-Ringer bicarbonate medium, supplemented with bovine serum albumin (4 mg/ml) and the vitamins and amino acids (essential and nonessential) in Minimum Essential Medium (without phenol red or antibiotics). The incubations were conducted at 39 degrees C for three 2-h periods; the second and third periods included an E2 or catechol estrogen treatment. Release of PGF2 alpha into the culture medium decreased (p less than 0.001) linearly with increasing concentrations of 2-OH-E2 in both periods. Release of PGE was not affected by 2-OH-E2, therefore 2-OH-E2 increased (p less than 0.06) the PGE:PGF2 alpha. When E2 was added to the medium, release of PGE was decreased (p less than 0.01) during the second and third periods. Release of PGF2 alpha also was decreased (p less than 0.05) by E2 during period 2, but E2 did not alter the PGE:PGF2 alpha. Content of PGs in blastocysts at recovery was less than 10% of the PGs released in vitro. Therefore, these studies demonstrate effects of both the primary and catechol forms of E2 on the synthesis of PGE and PGF2 alpha. Catechol estrogens and E2 may inhibit PG synthesis and modify the PGE:PGF2 alpha during the establishment of pregnancy in pigs.     

Effect of in vitro heat shock upon the synthesis and secretion of prostaglandins and protein by uterine and placental tissues of the sheep

The objectives of this study were to determine the secretion patterns of prostaglandins (PG) and protein during mid- (Day 100) and late- (Day 140) pregnancy in the ewe and to ascertain whether that pattern is altered by in vitro heat shock. Explant cultures were prepared from intercaruncular endometrium, caruncular endometrium, fetal cotyledon and interplacentomal placenta. Cultures were incubated at 39 or 42 degrees C for 18 h in the presence of arachidonic acid or L-[4,5(3)H]leucine. There were no effects of day of gestation or consistent effects of temperature upon de novo synthesis of tissue and secretory protein. Elevated temperature generally depressed PGE(2) secretion by maternal tissues and PGF secretion by caruncular endometrium but had little effect on PGE(2) release by fetal tissues or on PGF release by intercaruncular endometrium or fetal tissues. Day of gestation by tissue type interactions were found for PGF and PGE(2) release. At Day 100, maternal tissues secreted more PGF and PGE(2) than fetal tissues; at Day 140, PG secretion from fetal tissues was greater than at Day 100, and fetal PGE(2) release exceeded release from maternal tissues. Tissue proteins resolved by SDS-PAGE revealed the appearance in heat-shocked tissue of 93 and 72 kDa heat-shock proteins. In conclusion, elevated temperature depressed PGE(2) release, particularly from maternal tissues. Changes in PGE(2) suggest that the increase in utero-placental PGE(2) with increasing gestational age is due to changes in secretion of the fetal placenta.     

Effects of tumor necrosis factor-alpha on secretion of prostaglandins E2 and F2alpha in bovine endometrium throughout the estrous cycle

To determine the physiological significance of tumor necrosis factor-alpha (TNFalpha) in the regulation of endometrial prostaglandin (PG) release in cattle, we investigated the effects of TNFalpha on the secretion of PGE2 and PGF2alpha by bovine endometrium during the estrous cycle. Bovine uteri were classified into six stages (estrus: Day 0, early luteal 1: Days 2 to 3, early luteal 11: Days 5 to 6, mid-luteal: Days 8 to 12, late luteal: Days 15 to 17 and follicular: Days 19 to 21). After 1 h of pre-incubation, endometrial tissues (20 to 30 mg) were exposed to 0 or 0.6 nM TNFalpha for 4 h. The PGE2 concentrations in the medium were higher in the luteal stages than in the follicular stage and in estrus. In contrast, PGF2alpha concentrations were higher in the follicular stage and in estrus than in the luteal stages. The ratio of the basal concentrations of PGE2 and PGF2alpha (PGE2/PGF2alpha ratio) was higher in the luteal stages than in the follicular stage and in estrus. Although TNFalpha stimulated both PGE2 and PGF2alpha secretion during the entire period of the estrous cycle, the level of stimulation of TNFalpha on PGE2 output by the bovine endometrium does not show the same cyclical changes as that shown on PGF2alpha output. The stimulation of TNFalpha resulted in a decrease in the PGE2/PGF2alpha ratio only in the late luteal stage. Furthermore, TNFalpha stimulated PGE2 secretion in stromal, but not epithelial cells. The overall results suggest that TNFalpha is a potent regulator of endometrial PGE2 secretion as well as PGF2alpha secretion during the entire period of estrous cycle, and that TNFalpha plays different roles in the regulation of secretory function of bovine endometrium at different phases of the estrous cycle.