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Biology of Reproduction 63, 1642-1647 (2000)
© 2000 Society for the Study of Reproduction, Inc.

Regular Article

Time-Dependent Ovulation Inhibition of a Selective Progesterone-Receptor Antagonist (Org 31710) and Effects on Ovulatory Mediators in the In Vitro Perfused Rat Ovary1

Marita Pall2,a, Masato Mikunia, Kenrokuro Mitsubea, and Mats Brännströma

a Department of Obstetrics and Gynecology, Göteborg University, S-41345 Göteborg, Sweden

ABSTRACT

Progesterone (P) is one of several local mediators in the ovulatory cascade in the rat. The precise mechanisms of action for P in ovulation and in what phase of the ovulatory process P is critical, however, need to be clarified. The present study used a selective P-receptor antagonist, Org 31710, in the in vitro perfused rat ovary model to examine the local role of P and possible effects on prostaglandin (PG) and plasminogen-activator (PA) release in ovulation. Ovaries from eCG (15 IU)-primed rats were perfused for 20 h with LH (0.2 µg/ml) and 3-isobutyl-1-methylxanthine (IBMX, 200 µM) to induce ovulation (median = 10.0, 25%–75% range = 8.5–13). Org 31710 was added at either 0, 3.5, 7, or 9 h after LH+IBMX, resulting in significant suppression of ovulation after addition at 0 and 3.5 h (1.0, 1–5.5; and 5.0, 2.5–7.75 ovulations, respectively) but no suppressive effect when added at later time points. Progesterone and estradiol levels in the perfusion media were increased after LH+IBMX but were not affected by the presence of Org 31710. Ovarian tissue levels of PGE2, PGF2{alpha}, and PA activity were measured in ovaries that had been perfused for 10 h, a time that was 2 to 5 h before anticipated ovulation. The presence of Org 31710 significantly decreased the levels of PGE2, PGF2{alpha}, and PA activity. These results suggest that P is essential in ovulation during the initial stages of the ovulatory process. The effect of P to facilitate ovulation seems to relate to stimulation of the PG- and PA-mediator systems.

ovulation, progesterone, progesterone receptor

INTRODUCTION

The ovulatory process involves local action of several mediators, which are induced by the preovulatory LH surge. These mediators act in an intricate network to degrade the follicle wall and to induce the vascular changes necessary to accomplish rupture of the wall and release of the oocyte. Shortly after the LH surge, production of progesterone (P), estradiol (E2), and androgens in the preovulatory follicle is accelerated because of the induction of steroidogenic enzymes [1]. Estradiol and androgen synthesis is shut down approximately 4 to 6 h after the LH surge in the rat, but a high P synthesis persists [2, 3]. Evidence suggests that the initial increase of E2 [4] and androgens [5] has no importance in ovulation. Earlier results, however, showed P to be important. Administration of antiserum to P inhibits ovulation in vivo in the rat [6]. Inhibitors of 3ß-hydroxysteroid dehydrogenase (3ß-HSD) suppress ovulation when administered in vivo [7, 8] and in the in vitro perfused rat ovary system [5]. In the latter study, suppression of ovulation caused by 3ß-HSD inhibition was reversed by exogenous administration of P but not by testosterone. Mice carrying a null mutation of the P-receptor (PR) gene have provided further support for a multifunctional role of P in reproductive processes, because female knockout mice display significant defects in all reproductive tissues, including a blockage of ovulation [9]. In this PR knockout animal model, absence of PR in nonovarian tissues (e.g., hypothalamus and pituitary gland) may, of course, affect ovarian cyclicity. Results of a recent study using ovariectomized PR-/- mice suggested that PR is required for transmission of E2-induced signals leading to the preovulatory gonadotropin surge, because impaired LH/FSH response to exogenous E2 and GnRH pulses were seen [10].

Earlier studies on the action of P in ovulation have involved specific inhibitors of key steroidogenic enzymes [5, 7, 11] or the widely used PR antagonist RU486 [12–15]. RU486 has a high affinity for PRs and for the glucocorticoid receptor [16]. Results of studies in vivo have shown that administration of RU486 affects female fertility by means of reduced ovulation [12, 13], inhibition of implantation [17], and as an abortifacient [18]. Several mechanisms have been proposed by which RU486 may inhibit ovulation in vivo, including an increase of peripheral androgen levels [19], which could induce atresia by decreased follicular responsiveness to E2 [20]. An effect of RU486 to reduce the LH surge has also been discussed [12, 15]. Results of subsequent experiments utilizing the in vitro perfused rat ovary model [21] have demonstrated that 50 µM RU486 can inhibit ovulation at the ovarian level without affecting the LH+[3-isobutyl-1-methylxanthine] (IBMX)-stimulated P or E2 release. In the present study, we used the more selective PR antagonist Org 31710 and the in vitro perfused rat ovary model to examine the effect on rat ovulation, steroid release, and possible effects on plasminogen-activator (PA)- and prostaglandin (PG)-mediator pathways at the ovarian level.

MATERIALS AND METHODS

Animals

Immature Sprague-Dawley rats (B&K Universal AB, Sollentuna, Sweden) were kept under controlled light conditions (L14:D10) with free access to pellet food and water. The weight- and litter-matched rats were allocated to control and experimental groups. All experiments were performed according to the principles and procedures outlined in the National Institutes of Health Guide for Use of Laboratory Animals and were approved by the Animal Ethics Committee of Göteborg University.

Hormones and Chemicals

Ovine luteinizing hormone (NIADDK-oLH-26) and Org 31710 were kindly provided by the NIADDK and National Hormone and Pituitary Program (Rockville, MD) and Organon (Oss, The Netherlands), respectively. Equine CG and IBMX were from Sigma Chemical Company (St Louis, MO), ketamine (Ketalar) from Parke-Davis (Ann Arbor, MI), xylazine (Rompun) from Bayer (Leverkusen, Germany), Medium 199 from GIBCO (Rockville, MD), gentamicin sulfate from Biological Industries (Kibbutz Beit Haemak, Israel), BSA (Fraction V) from Boehringer Mannheim (Mannheim, Germany), insulin from Novo-Nordisk (Copenhagen, Denmark), and heparin from Lövens (Ballerup, Denmark).

Rat Ovarian Perfusion

Immature rats were primed with 15 IU of eCG at 0900 on Day 27 of age to obtain a first generation of preovulatory follicles. Forty-eight to fifty hours later, the rats were anesthetized with an i.p. injection of a combination of ketamine and xylazine (40 and 6.5 mg/kg body weight, respectively). Heparin sulfate (300 IU) was injected i.v. through a femoral vein. Laparotomy for surgical removal of the right ovary and its vasculature was performed, after which the animal was immediately killed as described elsewhere [22]. The caudal mesenteric artery, bilateral ileolumbar arteries and veins, and left renal and ovarian arteries and veins were ligated and severed. The aorta and inferior vena cava were then cannulated just cranial to the aortic bifurcation and in a cephalic direction. Three unpaired dorsal lumbar arteries and the distal part of the aorta and vena cava were severed and ligated, followed by removal of the perfusion specimen, including the right ovary with its vasculature. The ovarian bursa was gently opened and the specimen manually perfused with 37°C NaCl before being placed into the perfusion chamber. The aortic catheter was connected to the perfusion apparatus and preperfused for 30 to 60 min. Only specimens with a flow rate of 0.7 to 1.2 ml/min, at a pressure of 80 to 90 mm Hg during the initial 30-min period, were used for experiments. A long series of control experiments showed that higher or lower flow rates, indicative of vascular leakage or clotting, resulted in suboptimal steroid output and no ovulations.

Perfusions were performed in a recirculating system [22] that was modified to contain only 30 ml of Medium 199 with Earle salts supplemented with gentamicin sulfate (50 µg/ml), insulin (0.4 IU/ml), and 4% BSA.

Experimental Design

The medium was supplemented at 30 min after the start of perfusion start (time point 0 h) with LH and IBMX at initial concentrations of 0.2 µg/ml and 200 µM, respectively. The phosphodiesterase inhibitor IBMX was present to achieve optimal ovulatory stimulation [23], with an ovulation rate comparable to that in vivo [24]. In the experiments to study the ovulation rate, the isolated ovaries were perfused in vitro for 20 h. Controls (n = 8) were given LH+IBMX and 0.1 ml of ethanol (diluent for Org 31710) at 0 h. Org 31710 (10 µM) was added at either 0 (n = 5), 3.5 (n = 7), 7 (n = 5), or 9 h (n = 5). The concentration of Org 31710 (10 µM) was chosen based on results from another in vitro study showing effective inhibition of the proliferation of breast carcinoma cells at this concentration [25] and on our own experience regarding the effective concentrations needed when using other specific blockers in this system [26, 27].

The ovulation rate was determined by counting the number of ovulated oocytes found in the perfusion chamber after the completion of perfusion. For measurements of steroid levels in the perfusion media, 1-ml samples were obtained at 0, 1, 3, 5, 7, 10, and 20 h of perfusion. Thereafter, an equal amount of fresh medium, excluding LH and IBMX, was added back immediately after sampling, which resulted in a slight decrease of LH+IBX concentrations throughout the perfusion period. The samples were frozen at -70°C until analysis.

To investigate intraovarian levels of PG and PA activity, ovaries were perfused for 10 h after LH+IBMX with or without Org 31710 (10 µM) administration (at time point 0 h) as described earlier. This time point is 2 to 5 h before anticipated follicular rupture in this animal model in vivo [24] and in a similar in vitro perfusion system [22]. At the end of perfusion, each ovary was bisected, and the pieces were individually snap frozen in liquid nitrogen and stored at -70°C until analysis.

Assays

Progesterone and E2 concentrations in sampled perfusion media were analyzed using in-house radioimmunoassays [28, 29]. The 10-h perfused ovarian tissues were homogenized (glass-glass homogenizer at 5000 rpm for 30 sec) in 1 ml of buffer (0.1 M acetate buffer at pH 4.5 for the PGE2 and PGF2{alpha} assays and 0.05 M Tris buffer at pH 8.0 for the PA assay), centrifuged at 10 000 x g for 20 min at 4°C, and the supernatants further analyzed. The PGE2 was analyzed by an enzyme immunoassay kit (RPN222, Amersham, Buckinghamshire, UK), and PGF2{alpha} was measured by a radioimmunoassay kit (TRK900, Amersham).

The PA activity was analyzed using a modification of a procedure previously described by Espey et al. [30, 31]. The homogenized ovarian tissue was sonicated on ice (twice for 15 sec each time) and subsequently centrifuged at 10 000 x g for 20 min at 4°C. The supernatant was used for further assay. Twenty microliters of ovarian extract or standard dilution were mixed with 100 µl of substrate S-2215 and 20 µl of plasminogen (Chromogenix AB, Mölndal, Sweden) and then incubated for 1 h at 37°C. The reaction was stopped by adding 75 µl of 50% acetic acid, and the optical density of the final reaction was measured at 405 nm. Protein levels in supernatants were assayed by BCA Protein Assay kit (Pierce, Rockford, IL).

Statistics

Data from all experiments covered a broad range of values and were not normally distributed. Therefore, nonparametric tests were used in the data analysis. Data are expressed as medians and as 25–75 percentiles. Statistical differences concerning ovulation rate and steroid levels of 20-h perfusions were evaluated by the Kruskal-Wallis rank test, followed by the Mann-Whitney U-test. Comparisons of ovarian levels of PG and PA activity were performed with the Mann Whitney U-test. A P value < 0.05 was considered to be significant.

RESULTS

Effects on Ovulation Rate

Stimulation with LH+IBMX resulted in ovulations from all control ovaries (Fig. 1). Addition of Org 31710 (10 µM) at 0 or 3.5 h to LH+IBMX stimulated ovaries significantly (P < 0.01 and < 0.05, respectively) suppressed the ovulation rate. Administration of Org 31710 at 7 or 9 h did not affect the LH+IBMX-induced ovulation rate (Fig. 1).



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  		FIG. 1. Ovulation numbers in perfusions with a selective progesterone receptor antagonist (Org 31710, 10 µM) administered at different time points in relation to the addition of LH+IBMX. Org 31710 added at 0 and 3.5 h significantly reduced ovulation number, whereas administration at 7 and 9 h did not alter the ovulation number. Medians are indicated by horizontal lines. LH/IBMX = LH+IBMX. *P < 0.05, **P < 0.01

Effects on Steroidogenesis

Progesterone and E2 levels in the perfusion medium increased after addition of LH+IBMX and plateaued at 3 h of perfusion (Figs. 2 and 3). Presence of Org 31710 from 0 h (Figs. 2 and 3) and addition at 3.5, 7 (data not shown), or 9 h (Figs. 2 and 3) did not significantly influence either P or E2 levels at any time point.



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  		FIG. 2. The effect of a selective progesterone receptor antagonist (Org 31710, 10 µM) on progesterone levels in the media of ovaries stimulated by LH+IBMX. Org 31710 was added to the perfusate at 0 h (n = 5) or 9 h (n = 5). Bars indicate 10%–90% range, boxes indicate 25%–75% range, and horizontal bars indicate medians

Effects on Ovarian Levels of PG and PA Activity

In the 10-h perfused ovaries, Org 31710 significantly (P < 0.01) decreased both intraovarian PGE2 levels (Fig. 4) and PGF2{alpha} levels (Fig. 5) compared with those of controls. Plasminogen-activator activity levels (Fig. 6) were significantly (P < 0.05) reduced by Org 31710 treatment compared with controls.



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  		FIG. 4. The effect of a selective progesterone receptor antagonist (Org 31710, 10 µM) on PGE2 levels in rat ovaries perfused for 10 h. The PGE2 levels in the LH/IBMX+Org 31710-treated ovaries (n = 6) were significantly lower than those in LH+IBMX controls (n = 11). Bars indicate 10%–90% range, boxes indicate 25%–75% range, and horizontal bars indicate medians. LH/IBMX = LH+IBMX. **P < 0.01



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  		FIG. 5. The effect of a selective progesterone receptor antagonist (Org 31710, 10 µM) on PGF2{alpha} levels in rat ovaries perfused for 10 h. The PGF2{alpha} levels in the LH/IBMX+Org 31710-treated ovaries (n = 6) were significantly lower than those in LH+IBMX controls (n = 11). Bars indicate 10%–90% range, boxes indicate 25%–75% range, and horizontal bars indicate medians. LH/IBMX = LH+IBMX. **P < 0.01



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  		FIG. 6. The effect of a selective progesterone receptor antagonist (Org 31710, 10 µM) on PA levels in rat ovaries perfused for 10 h. The PA levels in the LH/IBMX+Org 31710-treated ovaries (n = 12) were significantly lower than those in LH+IBMX controls (n = 11). Bars indicate 10%–90% range, boxes indicate 25%–75% range, and horizontal bars indicate medians. LH/IBMX = LH+IBMX. *P < 0.05

DISCUSSION

Several lines of evidence suggest that LH-induced increase in follicular P production is important for ovulation to proceed normally in the rat. The major objectives of the present study were to investigate the mechanisms and time dependency for P action in the ovulatory process by using the selective PR antagonist Org 31710. This PR antagonist possesses minimal antiglucocorticoid action compared with the more commonly used PR antagonist RU486. Results of pharmacological studies have shown that Org 31710 and RU486 exhibit similar binding affinity to the cytosolic PR [32, 33], but that Org 31710 displays only 1/30th of the binding of RU486 to the glucocorticoid receptor [32], with biological antiglucocorticoid effects being notably lower [32, 34]. The glucocorticoid receptor is present in the rat ovary [35], and a possible role of glucocorticoids on the ovary and on ovulation has been suggested [36].

The main findings of the present study suggest that P plays an essential role at the ovarian level during the first hours of the ovulatory process. A reduction in ovulation was seen when Org 31710 was added at 0 and 3.5 h but not at 7 or 9 h. Furthermore, a P-induced stimulation of PG- and PA-mediator systems may be involved, because PA activity as well as PGE2 and PGF2{alpha} levels decreased when Org 31710 was administered concomitantly with LH+IBMX.

Marked changes in P synthesis and PR distribution occur at ovulation in the rat. The ovarian levels of P increase more than 50-fold shortly after hCG administration to immature, eCG-primed rats [8]. The predominant form of PR in the rat is the A form [37], which is absent in smaller follicles but rapidly and transiently induced in granulosa cells [38] and in theca cells of preovulatory follicles 4 h after the preovulatory surge of LH/hCG [39]. One major objective of the present study was to examine, in a more detailed way, whether a critical time period exists at the ovarian level during which PR activation is a prerequisite for rupture. Results of an in vivo rat study using the 3ß-HSD inhibitor epostane showed effective inhibition of ovulation when administered between 1 h before and 5 h after an ovulatory dose of hCG [24]. Results of the present study with Org 31710 and isolated perfused rat ovaries demonstrate an ovary-specific functional role of P/PR activation up to at least 3.5 h after hCG/LH administration. During the early P-critical time period, increased follicular levels of many ovulation-associated mediators are seen [40]. The importance of a general gene expression and protein synthesis during the first hours of the ovulatory process has been demonstrated by results of experiments utilizing different translational inhibitors and isolated perfused rat ovaries [41].

Prostaglandins play a role in ovulation. The effects of Org 31710 on intraovarian PG levels were examined in this study, and levels of PGE2 and PGF2{alpha}, after 10 h perfusion, were both reduced to approximately 50% of control values. Earlier results have shown that peak levels of PGE2 and PGF2{alpha} in the ovary are achieved 6 to 10 h after hCG [8]. This points toward a facilitative role of PR activation in the control of ovarian PG synthesis, which is in line with observations of decreased cyclo-oxygenase (COX) expression in the primate endometrium after treatment with antiprogestins [42]. Although PGs are accepted as ovulatory mediators, the results of a recent study using a selective COX-2 inhibitor (i.e., NS-398) demonstrated a discrepancy between PG levels and ovulation reduction, because moderate PG inhibition did not affect the ovulation rate, which was affected only when PG production was decreased by nearly 95% [26]. A reason for the ovulation-inhibiting effect concomitant with the relatively modest depression of ovarian PG levels seen in the present study may relate to additional effects by Org 31710 on other mediator systems that are active in the ovulatory cascade.

The PA/plasmin system has been suggested to play a role in oocyte expulsion by initiating proteolytic processes, most likely by collagenase activation [43, 44]. However, results of studies with urokinase- and tissue-type PA double-knockout mice demonstrated only a 26% reduced ovulation rate, suggesting that PA was functional but not obligatory for this process [45]. In the present study, total ovarian PA was reduced approximately 50% by Org 31710, which is in line with previous results in the rat involving steroid- and eicosanoid-synthesis inhibitors that indicated P may promote PA activity before ovulation [46]. A regulatory role for P in the activation of other ovulation-associated proteases, such as matrix metalloproteinases (MMP), has been suggested as well, because administration of a 3ß-HSD inhibitor to gonadotropin-treated macaques resulted in lower levels of MMP mRNA in granulosa cells [47]. Taken together, the results from these different experiments point toward a key regulatory role of P in protease activity locally in the ovary.

Ovarian secretion of P and E2 was not influenced by the addition of Org 31710, which is in agreement with previous reports [21, 48] in which RU486 did not significantly change the steroid levels in perfusions with rats and rabbits, respectively. An in vivo study using another selective antiprogestin, onapristone, found a decrease in both ovarian and peripheral blood levels of P when added 6 and 12 h before hCG administration [39]. In the latter study, serum P levels were reduced before those in ovarian tissue, which might have resulted from the contribution of extraovarian P production, which was excluded in our isolated ovarian perfusion model.

The results of this study demonstrate a critical, local role for PR early in the ovulatory process. Progesterone probably does not exhibit direct effects on follicular wall degradation but, rather, exerts a regulatory function on other mediator pathways, such as the PA/plasmin and PG systems. These mediators appear to have important and redundant functions in the complicated cascade resulting in oocyte expulsion.



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  		FIG. 3. The effect of a selective progesterone receptor antagonist (Org 31710, 10 µM) on estradiol levels in the media of ovaries stimulated by LH+IBMX. Org 31710 was added to the perfusate at 0 h (n = 5) or 9 h (n = 5). Bars indicate 10%–90% range, boxes indicate 25%–75% range, and horizontal bars indicate medians

FOOTNOTES

First decision: 11 April 2000.

1 Supported by grants from the Swedish Medical Research Council (11607 to M.B.), Hjalmar Svensson Foundation, and Medical Faculty of Göteborg University. Back

2 Correspondence: Marita Pall, Department of Obstetrics and Gynecology, Göteborg University, Sahlgrenska University Hospital, S-41345 Göteborg, Sweden. FAX: 46 31 829248; mspall{at}hotmail.com Back

Accepted: July 13, 2000.

Received: March 15, 2000.

REFERENCES

  1. Rodgers RJ. Steroidogenic cytochrome P450 enzymes and ovarian steroidogenesis. Reprod Fertil Dev 1990; 2:153–163.[CrossRef][Medline]
  2. Lieberman ME, Barnea A, Bauminger S, Tsafriri A, Collins WP, Lindner HR. LH effect on the pattern of steroidogenesis in cultured graafian follicles of the rat: dependence on macromolecular synthesis. Endocrinology 1975; 96:1533–1542.[Abstract/Free Full Text]
  3. Goff AK, Henderson KM. Changes in follicular fluid and serum concentrations of steroids in PMS-treated immature rats following LH administration. Biol Reprod 1979; 20:1153–1157.[Abstract]
  4. Morioka N, Brännström M, Koos RD, LeMaire WJ. Ovulation in the perfused ovary in vitro: further evidence that estrogen is not required. Steroids 1988; 51:173–183.[CrossRef][Medline]
  5. Brännström M, Janson PO. Progesterone is a mediator in the ovulatory process of the in vitro-perfused rat ovary. Biol Reprod 1989; 40:1170–1178.[Abstract]
  6. Mori T, Suzuku A, Nishimura T, Kambegawa A. Inhibition of ovulation in immature rats by antiprogesterone antiserum. J Endocrinol 1977; 73:185–186.[Abstract/Free Full Text]
  7. Snyder B, Beecham G, Schane H. Inhibition of ovulation in rats with epostane, an inhibitor of 3ß-hydroxysteroid dehydrogenase. Proc Soc Exp Biol Med 1984; 176:238–242.[CrossRef][Medline]
  8. Espey LL, Tanaka N, Adams RF, Okamura H. Ovarian hydroxyeicosatetraenoic acids compared with prostanoids and steroids during ovulation in rats. Am J Physiol 1991; 260:E163–E169
  9. Lydon JP, DeMayo FJ, Conneely OM, O'Malley BW. Reproductive phenotypes of the progesterone receptor null mutant mouse. J Steroid Biochem Mol Biol 1996; 56:66–77.
  10. Chappell PE, Schneider JS, Kim P, Xu M, Lydon JP, O'Malley BW, Levine JE. Absence of gonadotropin surges and gonadotropin-releasing hormone self-priming in the ovariectomized (OVX), estrogen (E2)-treated, progesterone receptor knockout mice. Endocrinology 1999; 140:3653–3658.[Abstract/Free Full Text]
  11. Lipner H, Greep RO. Inhibition of steroidogenesis at various sites in the biosynthetic pathway in relation to induced ovulation. Endocrinology 1971; 88:602–607.[Abstract/Free Full Text]
  12. Uilenbroek JTL. Hormone concentrations and ovulatory response in rats treated with antiprogestogens. J Endocrinol 1991; 129:423–429.[Abstract/Free Full Text]
  13. Van der Schoot P, Bakker GH, Klijn JG. Effects of the progesterone antagonist RU486 on ovarian activity in the rat. Endocrinology 1987; 121:1375–1382.[Abstract/Free Full Text]
  14. Rao IM, Mahesh VB. Role of progesterone in the modulation of the preovulatory surge of gonadotropins and ovulation in the pregnant mare's serum gonadotropin-primed immature rat and the adult rat. Biol Reprod 1986; 35:1154–1161.[Abstract]
  15. Sanchez-Criado JE, Bellido C, Galiot F, Lopez FJ, Gaytan F. A possible dual mechanism of the anovulatory action of antiprogesterone RU486 in the rat. Biol Reprod 1990; 42:877–886.[CrossRef][Medline]
  16. Moguilewsky M, Philibert D. RU 38486: potent antiglucocorticoid activity correlated with strong binding to the cytosolic glucocorticoid receptor followed by an impaired activation. J Steroid Biochem 1984; 20:271–276.[CrossRef][Medline]
  17. Gemzell-Danielsson K, Swahn M-L, Svalander P, Bygdeman M. Early luteal phase treatment with mifepristone for fertility regulation. Hum Reprod 1993; 8:870–873.[Abstract/Free Full Text]
  18. Ulmann A, Silvestre L, Chemana L, Rezvani Y, Renault M, Aguillaume CJ, Baulieu EE. Medical termination of early pregnancy with mifepristone (RU486) followed by a prostaglandin analogue. Acta Obstet Gynecol Scand 1992; 71:278–283.[Medline]
  19. Sanchez-Criado JE, Tebar M, Sanchez A, Gaytan F. Evidence that androgens are involved in atresia and anovulation induced by antiprogesterone RU486 in rats. J Reprod Fertil 1993; 99:173–179.[Abstract/Free Full Text]
  20. Erickson GF. An analysis of follicle development and ovum maturation. Semin Reprod Endocrinol 1986; 4:233–254.[CrossRef]
  21. Brännström M. Inhibitory effect of mifepristone (RU486) on ovulation in the isolated perfused rat ovary. Contraception 1993; 48:393–402.[CrossRef][Medline]
  22. Brännström M, Johansson BM, Sogn J, Janson PO. Characterization of an in vitro perfused rat ovary model: ovulation rate, oocyte maturation, steroidogenesis and influence of PMSG priming. Acta Physiol Scand 1987; 130:107–144.[Medline]
  23. Peterson CM, Hales HA, Hatasaka H, Mitchell MM, Rittenhouse L, Jones KP. Interleukin-1B (IL-1B) modulates prostaglandin production and the natural IL-1 receptor antagonist inhibits ovulation in the optimally stimulated rat ovarian perfusion system. Endocrinology 1993; 133:2301–2306.[Abstract/Free Full Text]
  24. Tanaka N, Espey LL, Kawano T, Okamura H. Comparison of inhibitory actions of indomethacin and epostane on ovulation in rats. Am J Physiol 1991; 260:E170–E174.
  25. Iwasaki K, Underwood B, Herman M, Dinda S, Kodali S, Kloosterboer HJ, Hurd C, Moudgil VK. Effects of antiprogestins on the rate of proliferation of breast cancer cells. Mol Cell Biochem 1999; 198:141–149.[CrossRef][Medline]
  26. Mikuni M, Pall M, Peterson CM, Peterson CA, Hellberg P, Brännström M, Richards JS, Hedin L. The selective prostaglandin endoperoxide synthase-2 inhibitor, NS-398, reduces prostaglandin production and ovulation in vivo and in vitro in the rat. Biol Reprod 1998; 59:1077–1083.[Abstract/Free Full Text]
  27. Mikuni M, Brännström M, Hellberg P, Peterson CA, Pall M, Edwin SS, Peterson CM. Saralasin-induced inhibition of ovulation in the in vitro perfused rat ovary is not replicated by the angiotensin II type-2 receptor antagonist PD123319. Am J Obstet Gynecol 1998; 179:35–40.[CrossRef][Medline]
  28. Hillensjö T, Bauminger S, Ahren K. Effect of LH on the pattern of steroid production by preovulatory follicles of PMS-injected immature rats. Endocrinology 1976; 99:996–1002.[Abstract/Free Full Text]
  29. Hillensjö T, Magnusson C, Svensson U, Thelander H. Effect of luteinizing hormone and follicle-stimulating hormone on progesterone synthesis by cultured rat cumulus cells. Endocrinology 1981; 108:1920–1924.[Abstract/Free Full Text]
  30. Espey L, Shimada H, Okamura H, Mori T. Effect of various agents on ovarian plasminogen activator activity during ovulation in pregnant mare's serum gonadotropin-primed immature rats. Biol Reprod 1985; 32:1087–1094[Abstract]
  31. Espey L, Tanaka N, Winn V, Okamura H. Increase in ovarian kallikrein activity during ovulation in the gonadotropin-primed immature rat. J Reprod Fertil 1989; 87:503–508.[Abstract/Free Full Text]
  32. Kloosterboer HJ, Deckers GH, Schoonen WG. Pharmacology of two new very selective antiprogestogens: ORG 31710 and ORG 31806. Hum Reprod 1994; 9:47–52.
  33. Mizutani T, Bhakta A, Kloosterboer HJ, Moudgil VK. Novel antiprogestins Org 31806 and 31710: interaction with mammalian progesterone receptor and DNA binding of antisteroid receptor complexes. J Steroid Biochem Mol Biol 1992; 42:695–704.[CrossRef][Medline]
  34. Koper JW, Molijn GJ, van Uffelen CJC, Stigter E, Lamberts SWJ. Antiprogestins and iatrogenic glucocorticoid resistance. Life Sci 1997; 60:617–624.[CrossRef][Medline]
  35. Schreiber JR, Nakamura K, Erickson GF. Rat ovary glucocorticoid receptor: identification and characterization. Steroids 1982; 39:569–584.[CrossRef][Medline]
  36. Soliman KFA, Walker CA. Dexamethasone suppression of ovulation in PMS-treated immature rats. Experientia 1977; 33:400–401.[CrossRef][Medline]
  37. Natraj U, Richards JS. Hormonal regulation, localization, and functional activity of the progesterone receptor in granulosa cells of the rat preovulatory follicles. Endocrinology 1993; 133:761–769.[Abstract/Free Full Text]
  38. Park O-K, Mayo KE. Transient expression of progesterone receptor messenger RNA in ovarian granulosa cells after the preovulatory luteinizing hormone surge. Mol Endocrinol 1991; 5:967–978.[Abstract/Free Full Text]
  39. Donath J, Michna H, Nishino Y. The antiovulatory effect of the antiprogestin onapristone could be related to down-regulation of intraovarian progesterone (receptors). J Steroid Biochem Mol Biol 1997; 62:107–118.[CrossRef][Medline]
  40. Brännström M, Mikuni M, Peterson CM. Ovulation-associated intraovarian events. In: Filicori M, Flamigni C (eds.), The Ovary: Regulation, Dysfunction and Treatment. Amsterdam: Elsevier Science; 1996: 113–123.
  41. Brännström M, Boberg BM, Törnell J, Janson PO, Ahren K. Effects of inhibitors of protein synthesis on the ovulatory process of the perfused rat ovary. J Reprod Fertil 1989; 85:451–459.[Abstract/Free Full Text]
  42. Kim JJ, Wang J, Bambra C, Das SK, Dey SK, Fazleabas AT. Expression of cyclooxygenase-1 and -2 in the baboon endometrium during the menstrual cycle and pregnancy. Endocrinology 1998; 140:2672–2678.[Abstract/Free Full Text]
  43. Reich R, Tsafriri A, Mechanic G. The involvement of collagenolysis in ovulation in the rat. Endocrinology 1985; 116:522–527.[Abstract/Free Full Text]
  44. Murdoch WJ. Regulation of collagenolysis and cell death by plasmin within the formative stigma of preovulatory ovine follicles. J Reprod Fertil 1998; 113:331–336.[Abstract/Free Full Text]
  45. Leonardsson G, Peng XR, Liu K, Nordström L, Carmeliet P, Mulligan R, Collen D, Ny T. Ovulation efficiency is reduced in mice that lack plasminogen activator gene function: functional redundancy among physiological plasminogen activators. Proc Natl Acad Sci U S A 1995; 92:12446–12450.[Abstract/Free Full Text]
  46. Tanaka N, Espey LL, Stacy S, Okamura H. Epostane and indomethacin actions on ovarian kallikrein and plasminogen activator activities during ovulation in the gonadotropin-primed immature rat. Biol Reprod 1992; 46:665–670.[Abstract]
  47. Chaffin CL, Stouffer RL. Expression of matrix metalloproteinases and their tissue inhibitor messenger ribonucleic acids in macaque periovulatory granulosa cells: time course and steroid regulation. Biol Reprod 1999; 61:14–21.[Abstract/Free Full Text]
  48. Chen SH, Dharmarajan AM, Wallach EE, Mastroyannis C. RU468 inhibits ovulation, fertilization and early embryonic development in rabbits: in vivo and in vitro studies. Fertil Steril 1995; 64:627–633.[Medline]



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