Effect of low weekly doses of mifepristone on ovarian function and endometrial development

Subacute exposure to DEHP leads to impairing decidualization process and exacerbating the risk of early pregnancy miscar-riage in mice

OBJECTIVES

To investigate the effect of subacute exposure of Di (2-ethylhexyl) phthalate (DEHP) on endometrial decidualization in mice.

METHODS

CD1 mice were orally administrated with 300 mg·kg－1·d－1 (low-dose group), 1000 mg·kg－1·d－1 (medium-dose group), or 3000 mg·kg－1·d－1 DEHP (1/10 LD50, high-dose group) for 28 days, respectively. The early natural pregnancy model and artificially induced decidualization model were established, and the uterine tissues were collected on D7 of natural pregnancy and D8 of artificially induced decidualization, respectively. The effects of subacute exposure to DEHP on the decidualization of mice were detected by HE staining, Masson staining, TUNEL staining, and Western blotting, respectively. A model of spontaneous abortion was constructed in mice after subacute exposure to 300 mg·kg-1·d-1 DEHP, and the effect of impaired decidualization on pregnancy was investigated by observing the pregnancy outcome on the 10th day of gestation.

RESULTS

Compared with the control group, the conception rate was significantly lower in the high-dose DEHP subacute exposure group. HE staining showed that, compared with the control group, the decidual stromal cells in the low- and medium-dose exposure groups were disorganized, the nuclei of the cells were irregular, the cytoplasmic staining was uneven, and the number of polymorphonuclear cells was significantly reduced. Masson staining showed that compared with the control group, the collagen fibers in the decidua region of the DEHP low-dose group and the medium-dose group were more distributed, more abundant and more disorderly. TUNEL staining showed increased apoptosis in the decidua area compared to the control group. Western blotting showed that the expression of BMP2, a marker molecule for endometrial decidualization, was significantly reduced. The abortion rate and embryo resorption rate were significantly higher, and the number of embryos, uterine wet weight, uterine area and placenta wet weight were significantly lower in mice exposed to 300 mg·kg－1·d－1 DEHP than in control mice stimulated by mifepristone abortifacient drug.

CONCLUSIONS

Subacute exposure to DEHP leads to impaired endometrial decidualization during early pregnancy and exacerbates the risk of adverse pregnant outcomes in mice.

PXR mediates mifepristone-induced hepatomegaly in mice

Mifepristone (Mif), an effective synthetic steroidal antiprogesterone drug, is widely used for medical abortion and pregnancy prevention. Due to its anti-glucocorticoid effect, high-dose Mif is also used to treat Cushing's syndrome. Mif was reported to active pregnane X receptor (PXR) in vitro and PXR can induce hepatomegaly via activation and interaction with yes-associated protein (YAP) pathway. High-dose Mif was reported to induce hepatomegaly in rats and mice, but the underlying mechanism remains unclear. Here, the role of PXR was studied in Mif-induced hepatomegaly in C57BL/6 mice and Pxr-knockout mice. The results demonstrated that high-dose Mif (100 mg · kg^-1 · d^-1, i.p.) treatment for 5 days significantly induced hepatomegaly with enlarged hepatocytes and promoted proliferation, but low dose of Mif (5 mg · kg^-1 · d^-1, i.p.) cannot induce hepatomegaly. The dual-luciferase reporter gene assays showed that Mif can activate human PXR in a concentration-dependent manner. In addition, Mif could promote nuclear translocation of PXR and YAP, and significantly induced the expression of PXR, YAP, and their target proteins such as CYP3A11, CYP2B10, UGT1A1, ANKRD, and CTGF. However, Mif (100 mg · kg^-1 · d^-1, i.p.) failed to induce hepatomegaly in Pxr-knockout mice, as well as hepatocyte enlargement and proliferation, further indicating that Mif-induced hepatomegaly is PXR-dependent. In summary, this study demonstrated that PXR-mediated Mif-induced hepatomegaly in mice probably via activation of YAP pathway. This study provides new insights in Mif-induced hepatomegaly, and provides novel evidence on the crucial function of PXR in liver enlargement and regeneration.

Mifepristone mediates anti-proliferative effect on ovarian mesenchymal stem/stromal cells from female BRCA1-/2- carriers

INTRODUCTION

Women with hereditary mutation in breast cancer-associated genes (BRCA^1-/2- ) have a higher lifetime risk of developing ovarian cancer. Here, we aimed to investigate the effect of mifepristone, a selective progesterone receptor modulator of ovarian mesenchymal stem/stromal cells (MSC) from BRCA^1-/2- carriers.

MATERIAL AND METHODS

Ovarian BRCA^1-/2- MSC were positively selected using the markers CD90, CD73 and CD105 from nine healthy women. The effect of dose response and combination treatment with mifepristone and analogs of progesterone- or glucocorticoid-receptors were investigated on BRCA^1-/2- MSC in vitro using a panel of markers for proliferation (ki67, BrdU, CDK2, p21^CIP ), apoptosis (BAX, BCL2, CASPASE3), tumor suppression (TP53, PTEN) and cell survival (PI3KCA, MAPK3, mTOR).

RESULTS

The dose response with mifepristone treatment suggested an optimal effect with 10 μm mifepristone, exhibiting >90% viability and significantly reducing growth signaling markers (TP53 and MAPK3). Furthermore, combined treatment with progesterone plus mifepristone (PG+MIFE) gave an enhanced anti-proliferative effect in comparison with hydrocortisone plus mifepristone (HC+MIFE) by significantly reducing markers of proliferation (BrdU⁺ and Ki67 expression) and tumor suppressors (PTEN, TP53), and increasing the percentage of pro-apoptotic cells. Consequently, accumulation of p21^CIP together with reduced levels of CDK2 confirms growth inhibition by reversibly arresting cell-cycle progression at the G1-S phase, not by inducing apoptosis.

CONCLUSIONS

Our study showed an anti-proliferative effect on ovarian BRCA^1-/2- MSC on in vitro combined treatment with mifepristone and progesterone. These findings suggest that mifepristone or other selective progesterone receptor modulators could be developed as a preventive treatment and postpone early use of prophylactic salpingo-oophorectomy as well as reduce the risk of ovarian cancer.

Effects of low doses of mifepristone on human embryo implantation process in a three-dimensional human endometrial in vitro co-culture system

OBJECTIVES

We wanted to explore the effects of two different low doses (0.5μM and 0.05μM) of mifepristone, exposed during the receptive period, on the human embryo implantation process, using a well-established three-dimensional in vitro cell culture model, specifically developed to study this process.

METHODS

An in vitro three-dimensional cell culture model was constructed using human endometrial cells isolated from the endometrium of proven fertile women, collected on cycle day LH+4. After 5 days of culture, supernumerary human embryos were added and cultured for another 5 days with mifepristone 0.5μM (n=8) or 0.05μM (n=10) or vehicle as control (n=10). The cultures were checked for embryo attachment and terminated. We studied the expression of 16 reported endometrial receptivity markers in the endometrial constructs using real-time polymerase chain reaction.

RESULTS

None of the embryos in 0.5μM of mifepristone attached to the endometrial constructs (p=.004), whereas 4 out of 10 in 0.05μM (p=.3698) and 7 out of 10 embryos in the control group attached to the cultures. We found that most of the studied receptivity markers were significantly altered with mifepristone exposure in a similar direction in both treatment groups. Only IL6 was significantly differentially expressed between the treatment groups (p=.017).

CONCLUSION

We report for the first time that exposure to a low concentration (0.5μM) of mifepristone during the receptive period successfully inhibits human embryo implantation process in vitro. Further, we observed a dose-dependent effect of mifepristone on endometrial receptivity at the functional level.

IMPLICATION

This study contributes new knowledge that low dose of mifepristone during the short period of receptive phase can inhibit endometrial receptivity, which further promotes mifepristone as a contraceptive agent. This could give women a treatment choice to avoid unwanted pregnancy with high efficacy and minimal side effects.

Effects of mifepristone and quinestrol on the fertility of female Brandt’s voles (Lasiopodomys brandtii) in different reproductive phases

Mifepristone and quinestrol are effective drugs for controlling rodent fertility, but their inhibitory effectiveness during premating, early pregnancy, and late pregnancy is unknown. In this study, six groups of eight female Brandt’s voles (Lasiopodomys brandtii) were administered with mifepristone, quinestrol, or a control for three days during premating, early pregnancy, or late pregnancy. In the mifepristone-treated groups, the premating females bred, whereas the early and late pregnant females did not. The reproductive rate, litter size, average body mass at birth, and survival rate of pups did not significantly differ between the mifepristone-treated premating group and the control group. By contrast, quinestrol treatment completely inhibited fertility during the three reproductive phases. In addition, fertility was not completely restored in the second pairing. The reproductive rates were higher for mifepristone, both during early and late pregnancy, than for quinestrol, but both were lower than the control. Thus, mifepristone and quinestrol both inhibited the fertility of female Brandt’s voles at different reproductive periods. These results suggest that these two sterilants could be delivered during the reproductive season of the target pest animal.

Toward developing a once-a-month pill: a double-blind, randomized, controlled trial of the effect of three single doses of mifepristone given at midcycle on the pattern of menstrual bleeding

OBJECTIVE

To test the feasibility of timing the administration of mifepristone as a once-a-month contraceptive pill on the 12th day before the next menses, as calculated from the length of the previous menstrual cycles.

DESIGN

Double-blind, randomized, controlled trial.

SETTING

Five family planning centers across the world.

PATIENT(S)

Three hundred ninety-nine women attending family planning clinics.

INTERVENTION(S)

Randomized to receive 10, 25, or 200 mg of mifepristone or a placebo.

MAIN OUTCOME MEASURE(S)

Lengthening or shortening of the normal menstrual cycle length following administration of the drug by at least 5 days.

RESULT(S)

The menstrual period came within 5 days of the predicted date in 88% of women receiving the placebo, 84% of women receiving 10 mg, 72% of women receiving 25 mg of mifepristone, and only 48% of women treated with 200 mg of mifepristone. Increasing the dose of mifepristone was associated with an increased chance of having a delayed period (P<.001). Only 45% of women were in the peri-ovulatory phase of the cycle according to LH and P measurements on the day of drug administration. Women treated before ovulation were more likely to have delayed menses with all three doses of mifepristone.

CONCLUSION(S)

Because of the disruption in cycle length, it appears unlikely that mifepristone administered once a month, at a calendar-based time, would provide a reliable method of contraception.

Advances in uterine protein research: reproduction and cancer

Uterine protein research has advanced from the measurements of specific compounds to detailed analysis of the genes that regulate protein synthesis and build up the complex carbohydrate structures that play important functional roles. Some 80% of all human proteins are glycoproteins. Functional glycomics highlights the importance of glycosylation in glycoprotein function. Glycodelin is a representative example of functional glycomics because its various glycoforms have different functions. In the uterus, synthesis of glycodelin-A is temporally regulated by progesterone. During the estrogen-dominated fertile window, absence of glycodelin synthesis is significant because uterine glycodelin-A potently and dose-dependently inhibits sperm-egg binding, the initial step in fertilization. The anti-fertilization propensity of glycodelin-A during the luteal phase of the cycle is highly glycosylation-dependent, and there is an intricate functional interplay between spermatozoa, zona pellucida and the various glycodelin isoforms present in the uterine fluid, seminal plasma and follicular fluid, respectively. Endometrial glycodelin synthesis can be induced during the fertile window by administration of progestagens, such as in levonorgestrel hormone-releasing IUD and contraceptive implants. Glycodelin can be chemically modified in such a fashion that it blocks the binding site on CD4 for the HIV surface glycoprotein, synthesis of viral gp 120, and infection of peripheral blood mononuclear cells by the primary HIV isolate THA/93/051, thus potentially inhibiting HIV transmission. Now that a cell line producing the contraceptive isoform has been identified by recombinant technology, these findings may have application for locally applied antiviral contraception. Glycodelin also has immunosuppressive properties, suggesting that the recognition mechanisms in immune and reproductive systems may have converged. Given its inhibitory activity on natural killer cells, abundant at the fetomaternal interphase, the high glycodelin concentration at the same site suggests a role in fetomaternal defense mechanisms. This may be relevant in women with recurrent miscarriage, in whom both the serum and uterine fluid glycodelin concentrations are decreased. Experiments on cancer cell lines have demonstrated increased epithelial differentiation by glycodelin cDNA transfection, and also by co-culture of cancer cells with normal stromal cells in the presence of basement membrane components. Both approaches result in glycodelin expression concomitant with decreased cell proliferation and reversion of the malignant phenotype. These results suggest an active role of normal stromal cells, basement membrane components and glycodelin in epithelial differentiation and glandular morphogenesis. This disposition of glycodelin is significant in patients with certain carcinomas, in which glycodelin-expressing tumors carry better prognosis than glycodelin-negative tumors of the same clinical stage and histological grade. Research on functional glycomics continues to produce significant information on fundamental aspects of fertilization, implantation, pregnancy and cancer.

The pharmacokinetics of mifepristone in humans reveal insights into differential mechanisms of antiprogestin action

The pharmacokinetics of mifepristone is characterized by rapid absorption, a long half-life of 25-30 h, and high micromolar serum concentrations following ingestion of doses of >/=100 mg of the drug. The serum transport protein-alpha 1-acid glycoprotein (AAG)-regulates the serum kinetics of mifepristone in man. Binding to AAG limits the tissue availability of mifepristone, explaining its low volume of distribution and low metabolic clearance rate of 0.55 L/kg per day. In addition, the similar serum levels of mifepristone following ingestion of single doses exceeding 100 mg can be explained by saturation of the binding capacity of serum AAG. Mifepristone is extensively metabolized by demethylation and hydroxylation, the initial metabolic steps being catalyzed by the cytochrome P-450 enzyme CYP3A4. The three most proximal metabolites, namely, monodemethylated, didemethylated and hydroxylated metabolites of mifepristone, all retain considerable affinity toward human progesterone and glucocorticoid receptors. Also, the serum levels of these three metabolites are in ranges similar to those of the parent mifepristone. Thus, the combined pool of mifepristone-plus its metabolites-seems to be responsible for the biological actions of mifepristone. Recent clinical studies on pregnancy termination and emergency contraception have focused on optimization of the dose of mifepristone. In these studies it has become apparent that the doses efficient for pregnancy termination differ from those needed in emergency contraception-mifepristone is effective in emergency contraception at a dose of 10 mg, which results in linear pharmacokinetics. However, the >/=200 mg doses of mifepristone needed for optimal abortifacient effects of mifepristone result in saturation of serum AAG and thus nonlinear pharmacokinetics. In view of the pharmacokinetic data, it may be speculated that dosing of mifepristone for pregnancy termination and for emergency contraception could be reduced to approximately 100 mg and 2-5 mg, respectively. It remains to be seen whether the newly synthesized, more selective antiprogestins will prove more efficacious in the clinical arena.

Summary of evidence and research needs on the use of mifepristone in fertility regulation: consensus from the conference

The conference on the use of mifepristone to reduce unwanted pregnancy, sponsored by the World Health Organization, Concept Foundation and the Rockefeller Foundation, took place in Bellagio, Italy, between 24 and 28 September 2001. The objective of the conference was to review the scientific information and to evaluate the use of mifepristone for emergency contraception, luteal contraception and menstrual induction. Mifepristone is highly effective for emergency contraception but its advantages and disadvantages in comparison with levonorgestrel need to be further studied. Data indicate that mifepristone alone or in combination with misoprostol has potential for occasional use for women seeking help following repeated unprotected intercourse and/or when the interval between intercourse and treatment is more then 120 h. Administration of mifepristone immediately after ovulation seems to be an effective contraceptive method. However, before it can be used commonly, there is a need for a simple and inexpensive method to identify the right time in the cycle. Once-a-month treatment with mifepristone and misoprostol at the expected time of menstruation is not a practical method due to bleeding irregularities and timing of treatment. Menstrual induction with mifepristone and a suitable prostaglandin analogue is highly effective. A randomized comparison with manual vacuum aspiration is, however, needed before it can be recommended for routine use.

Mechanisms of action of mifepristone when used for emergency contraception

An emergency contraceptive method is used after coitus but before pregnancy occurs. The use of emergency contraception is largely underutilized worldwide. Recently, treatment with 10 mg mifepristone as a single dose has emerged as one of the most effective hormonal methods for emergency contraception, with very low side effects. However, the mechanism of action of mifepristone in humans when used for contraceptive purposes and especially for emergency contraception remains largely unknown. The objective of this review is to summarize available data on the effect of mifepristone on female reproductive functions relevant to emergency use of the compound. Taken together, available data from studies in humans indicate that the contraceptive effect of mifepristone used as a single low dose for emergency contraception is mainly due to impairment of ovarian function, either by blocking or postponing the luteinizing hormone surge, rather than to inhibiting of implantation.

Antiprogestins as a model for progesterone withdrawal

The key physiological function of the endometrium is preparation for implantation; and in the absence of pregnancy, menstruation and repair. The withdrawal of progesterone is the initiating factor for breakdown of the endometrium. The modulation of sex steroid expression and function with pharmacological agents has provided an invaluable tool for studying the functional responses of the endometrium to sex steroids and their withdrawal. By administration of the antiprogestin mifepristone, it is possible to mimic progesterone withdrawal and study local events in early pregnancy decidua that may play a role in the process of early pregnancy failure. Our data indicate that antagonism of progesterone action at the receptor level results in an up-regulation of key local inflammatory mediators, including NF-kappaB, interleukin-8 (IL-8), monocyte chemotactic peptide-1 (MCP-1), cyclooxygenase 2 (COX-2) and others in decidua. Bleeding induced by mifepristone in the mid-luteal phase of the cycle is associated with changes in the endometrium similar to those that precede spontaneous menstruation including up-regulation of COX-2 and down-regulation of PGDH. Administration of antagonists of progesterone provide an excellent model to study the mechanisms involved in spontaneous and induced abortion as well as providing information which may help devise strategies for treating breakthrough bleeding associated with hormonal contraception.

Chronic low-dose antiprogestin impairs preimplantation embryogenesis, but not oocyte nuclear maturation or fertilization in rhesus monkeys

Continual administration of low doses of the antiprogestin ZK137316 permits ovarian/menstrual cyclicity, but prevents pregnancy in female rhesus monkeys. The sites of contraceptive action remain unknown. This study determined whether chronic, low-dose antiprogestin exposure during follicular development impairs oocyte maturation in vivo, as well as fertilization and preimplantation embryogenesis in vitro. Adult, female rhesus monkeys exhibiting normal menstrual cycles received vehicle (n=9) or 0.03 mg ZK137316 (n=8)/kg body weight i.m. daily for 3 months. Controlled ovarian stimulation with recombinant gonadotropins was initiated in the 3rd month. Oocytes collected from preovulatory follicles were evaluated for nuclear maturity and inseminated in vitro. Preimplantation embryonic development was monitored in vitro. The total number of oocytes and percentage collected at each nuclear stage were similar in both groups. More (P<0.05) atretic oocytes were recovered following antiprogestin relative to vehicle treatment. Fertilization rates and percentages of embryos that progressed to the morula stage were similar between groups, but antiprogestin-treated females exhibited less (P<0.05) normal cleavage. Embryonic development was accelerated by 1 day (P<0.05) from the 16-cell to the morula stage in the antiprogestin group relative to vehicle. Despite this, the majority of embryos became blastocysts within 6 days in vitro in the antiprogestin group, but fewer expanded (P=0.09) and hatched (P<0.05) compared to vehicle. During in vivo treatment with chronic, low-dose antiprogestin, oocytes retained their ability to resume and complete meiosis as well as fertilize following insemination in vitro. However, preimplantation embryogenesis in vitro was impaired, particularly during the later stages of blastocyst development. Thus, antiprogestin exposure during follicular development altered oocyte functions that are critical for normal preimplantation embryogenesis; this may contribute to pregnancy prevention.

Effects of mifepristone on endometrial receptivity

At the development of receptivity the endometrium undergoes specific changes. Several factors have been suggested as markers of endometrial receptivity. A common feature for most of these factors is that they are directly, or indirectly, regulated by progesterone. The effect of various doses and regimens of mifepristone on endometrial development and markers of receptivity has been studied. Timed endometrial biopsies were assessed by immunhistochemistry, reverse transcriptase polymerase chain reaction (RT-PCR) and electron microscopy. In addition the contraceptive efficacy of these regimens was investigated. Administration of 200 mg of mifepristone immediately post ovulation has a pronounced effect on endometrial development and on suggested markers of receptivity. This regimen has been shown to be an effective contraceptive method. When 10 mg is given pre or post ovulation, only minor effects on the endometrium are observed. Our studies show that mifepristone, when administered in low doses that do not affect ovulation, significantly affects some of the studied markers of endometrial receptivity and reduces pregnancy rates; however, these activities are more pronounced with the higher dose, which is more effective. Our findings provide insight into the regulation of progesterone receptors of various suggested markers of endometrial receptivity and the possibility of using mifepristone for endometrial contraception.

Progesterone receptor isoform B in the human fallopian tube and endometrium following mifepristone

The distribution of progesterone receptor isoform B may have important clinical significance. The aim of this study was to compare the expression, localization and regulation of progesterone receptor isoform B in the human Fallopian tube and endometrium following mifepristone in a dose effective for contraception. Fertile women were treated with a single dose of 200 mg mifepristone on day luteinizing hormone (LH)+2. Biopsies were obtained from the Fallopian tube on day LH+4 to LH+6 and from the endometrium on day LH+6 to LH+8. Progesterone receptor isoform B expression was analyzed by immunohistochemistry and reverse transcriptase polymerase chain reaction. Treatment with mifepristone increased progesterone receptor isoform B concentration in epithelial and stromal cells in the Fallopian tube and also increased progesterone receptor isoform B concentration in the glandular cells of the endometrium. These results further support the hypothesis that the contraceptive effect of mifepristone when given postovulatory is primarily due to alteration of the peri-implantation milieu influencing endometrial receptivity.

Low-dose antiprogestin treatment prevents pregnancy in rhesus monkeys and is reversible after 1 year of treatment

BACKGROUND

Administration of low doses of an antiprogestin to rhesus monkeys permits ovarian/menstrual cyclicity, suppresses endometrial proliferation and prevents pregnancy without adverse or toxic side-effects after 5-6 months of daily treatment. The purpose of this study was to test the reversibility with respect to restoration of fertility after 1 year of low-dose antiprogestin treatment.

METHODS

This experiment included a daily 1 year vehicle- or antiprogestin-treatment interval followed by a 9 month post-treatment interval for adult, female rhesus monkeys (n = 5/group) of proven fertility and exhibiting regular menstrual cycles. Co-habitation occurred with a male of proven fertility and vaginal swabs were taken to identify the presence of sperm during the treatment (antiprogestin females) and post-treatment intervals (vehicle and antiprogestin females).

RESULTS

Mating and vaginal sperm were evident in all antiprogestin females during, and, in both groups, after treatment. Based on ultrasonography, none of the antiprogestin-treated females became pregnant during the treatment interval. However, upon cessation of treatment, pregnancy rates were similar between antiprogestin-treated (3/5) relative to vehicle-treated (4/5) females with live, healthy infants born in both groups. There were no differences between groups in fetal measurements, gestation lengths, live birth rates and infant weights.

CONCLUSIONS

The reversal of the anti-fertility effects of chronic, low-dose antiprogestin treatment supports the clinical feasibility of potent and selective antiprogestins as potential contraceptives for women.

Role of progesterone antagonists and new selective progesterone receptor modulators in reproductive health

Given the importance of progesterone in female reproductive health, it was inevitable that analogues of this molecule would be developed to treat a variety of gynecologic maladies. Such medications, termed progesterone antagonists, act to counteract the effect of progesterone. A newer class of molecules, the selective progesterone receptor modulators (SPRMs), have both agonist and antagonist activities depending upon the site of action. These compounds have been studied for their effect on endometrial growth, endometrial vascular development, the hypothalmic-pituitary-ovarian axis and cervical integrity. Such research has led to a number of potential clinical applications. Progesterone antagonists are well established in their use for termination of pregnancy, although SPRMs seem to have a diminished capacity for induction of abortion. Similarly, antagonists work well to soften and dilate the cervix before surgery, but such efficacy by SPRMs is unlikely. Other applications for progesterone antagonists include induction of labor, the treatment of endometriosis, fibroids and contraception; SPRMs also may prove useful in the treatment of endometriosis and fibroids, as well as for postmenopausal hormone replacement therapy and the treatment of dysfunctional uterine bleeding. Finally, these compounds may aid investigators in unraveling many of the nuances of the role of progesterone in reproductive function.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians Learning Objectives: After completion of this article, the reader will be able to describe the receptor action and selective modulation of progesterone, explain the effects of progesterone receptor modulators, and list the potential clinical applications of progesterone antagonists and selective progesterone receptor modulators.

New developments in contraceptive drugs for use by women

Since the oral contraceptive pill was first marketed in 1959, advances in contraceptive drugs for women have been limited to variations on the theme of oestrogen in combination with progestogen or progestogen alone. Alterations to the pill regimen, new progestogens and new delivery systems have increased choice but while these advances significantly improve acceptability, side effects and risks remain essentially unchanged. New ideas are in short supply. Antiprogesterones offer a new approach with a variety of dose regimens but their development has been seriously hampered by the politics associated with their abortifacient action. Other hormone antagonists as contraceptives seem a long way off. Immunocontraception is still at a very early stage. Genes, whose products are uniquely concerned with reproductive processes, promise new targets but radically new contraceptive drugs for women appear distant.

Glycodelin: a major lipocalin protein of the reproductive axis with diverse actions in cell recognition and differentiation

Glycodelin is a glycoprotein that belongs to the lipocalin superfamily. Depending on glycosylation, glycodelin appears in various isoforms. In the uterus, glycodelin-A is the major progesterone-regulated glycoprotein secreted into uterine luminal cavity by secretory/decidualized endometrial glands. The other tissues expressing glycodelin include fallopian tubes, ovary, breast, seminal vesicle, bone marrow, and eccrine glands. Glycodelin-A potently and dose-dependently inhibits human sperm-egg binding, whereas differently glycosylated glycodelin-S from seminal plasma has no such effect. Absence of contraceptive glycodelin-A in the uterus during periovulatory midcycle is consistent with an open "fertile window." Glycodelin induced by local or systemic administration of progestogens may potentially reduce the fertilizing capacity of sperm in any phase of the menstrual cycle. Glycodelin also has immunosuppressive activity. Its high concentration at the fetomaternal interface may contribute to protection of the embryonic semiallograft. Besides being an epithelial differentiation marker, glycodelin appears to play a role in glandular morphogenesis, as transfection of glycodelin cDNA into a glycodelin-negative breast cancer cells resulted in formation of gland-like structures, restricted proliferation, and induction of other epithelial markers. These various properties, as well as the chemistry, biology, and clinical aspects of glycodelin, continue to be areas of active investigation reviewed in this communication.

Mifepristone: bioavailability, pharmacokinetics and use-effectiveness

The potentiality of mifepristone as an abortifacient and contraceptive drug along with its pharmacokinetic parameters is reviewed. Mifepristone or RU486 acts as antagonist to progestational and glucocorticoid functions. It is an orally active compound with nearly 70% absorption rate but its bioavailability is reduced to around 40% because of the first-pass effect. Peak plasma concentrations of 1.9 +/- 0.8, 3.8 +/- 0.9 and 5.3 +/- 1.3 micromol/l are reached within 1-2 h after oral administration of 50, 200 and 600 mg mifepristone in women, respectively, and are maintained at relatively high level up to 48 or 72 h depending on the ingested dose. The plasma kinetics of mifepristone followed two-compartment open model with a mean alpha-half-life of 1.4h, volume of distribution 1.47 l/kg and beta-half-life of 20-30 h in most of the subjects studied. Clearance from the body was mainly through feces (83%). Biologically active mono-demethylated, di-demethylated and hydroxylated metabolites were found in plasma soon after oral administration of mifepristone. RU486 and its mono-demethylated metabolite bind to progesterone receptors with high affinity. Mifepristone-bound receptor dimers suppress transcription activation and thus, bring about anti-progestational activity that makes mifepristone a potential abortifacient and contraceptive agent. Clinical trials for termination of early pregnancy with 50-600 mg mifepristone plus a prostaglandin analogue achieved a success rate of 82-97%. However, abdominal pain, cramping, nausea, vomiting, bleeding and delay in onset of the next menstrual cycle were the side effects. Administration of 25 mg mifepristone twice 12h apart, as a post-coital contraceptive showed 100% contraceptive efficacy. A low dose of mifepristone which does not inhibit ovulation reduced fertility significantly by affecting endometrial milieu. These findings suggest that reduced dose(s) of mifepristone, 200 mg or less, may be used as a post-coital contraceptive and in combination with vaginal misoprostol for termination of early pregnancy with high efficacy and minimal or no side effects.

Glycodelin: a reproduction-related lipocalin

Glycodelin, a human lipocalin, is a major endometrial protein with at least two differentially glycosylated isoforms. Glycodelin-A (GdA) is purified from human mid-trimester amniotic fluid, where it is secreted from the decidualized endometrium. Glycodelin-S (GdS) is synthesized in the male reproductive tract, mainly in the seminal vesicles, and secreted into seminal plasma. These two glycodelin isoforms, glycosylated in a completely different manner, serve as a good model for studying the effects of glycosylation on protein function and physicochemical properties. We have reviewed here the structure, expression and biological functions of glycodelin.

Modulation of the action of chorionic gonadotropin in the baboon (Papio anubis) uterus by a progesterone receptor antagonist (ZK 137. 316)

Signals from the developing mammalian blastocyst rescue the corpus luteum (CL) and modulate the uterine environment in preparation for implantation and early pregnancy. Our previous studies demonstrated that both short- and long-term administration of chorionic gonadotropin (CG) markedly alters the morphology and the biochemical activity of the receptive endometrium. Because the effects of CG were superimposed on a progesterone-primed endometrium, this study was undertaken to determine if the inhibition of progesterone action by progesterone receptor antagonists (PRa) in intact and ovariectomized baboons would alter the action of CG on the endometrium at the time of uterine receptivity. In the short-term hCG-treated baboons, the PRa reduced the epithelial plaque reaction, completely inhibited alpha-smooth muscle actin (alphaSMA) expression in stromal fibroblasts, and induced the reappearance of the progesterone (PR) and estrogen (ERalpha) receptors in epithelial cells. However, this treatment protocol had no effect on the expression of glycodelin in the glandular epithelium. In contrast, glycodelin expression in addition to alphaSMA was suppressed in the ovariectomized animals. In the long-term hCG-treated baboons, the PRa had a similar effect on both alphaSMA, PR, and ER. In addition, this treatment also resulted in an inhibition of glycodelin expression in the glandular epithelium. These results indicate that blocking the action of progesterone on the endometrium even for a short period of time has a profound effect on the hCG-induced response in stromal fibroblasts. In contrast, for the diminution of glandular epithelial function in the presence of an ovary requires prolonged inhibition of progesterone action, suggesting a potential paracrine effect on the endometrium from the CL in response to hCG.

Local effects of mifepristone on the nonhuman primate endometrium

OBJECTIVE

To determine the effects of a low-dose mifepristone regimen on endometrium in the rhesus monkey by endometrial staging and analysis of molecular markers of endometrial receptivity.

DESIGN

A prospective, randomized comparative study.

SETTING

Academic research environment.

ANIMAL(S)

Normally cycling rhesus (Macaca mulatta) monkeys.

INTERVENTION(S)

Monkeys (5 per control or treatment group) received 0.03 mg of mifepristone in vehicle (sesame oil) per kilogram of body weight or vehicle daily from day 2 of the menstrual cycle to 7 days after the midcycle E2 surge.

MAIN OUTCOME MEASURE(S)

Serum estradiol (E2) and progesterone (P) levels; endometrial staging and immunoreactivity of leukemia inhibitory factor and interleukin-6 performed on fixed endometrial tissues; and relative abundance of endometrial estrogen and P receptor mRNA evaluated with semiquantitative reverse transcriptase polymerase chain reaction in which cyclophilin mRNA, a housekeeping gene product, was coamplified as the reference standard.

RESULT(S)

Mifepristone at 0.03 mg/kg/d induced a delay in the endometrial cycle with a shift from the late to midsecretory phase. This treatment regimen did not suppress the midcycle gonadotropin surge or, presumably, ovulation because P levels were normal during the midluteal phase. The staining intensity of leukemia inhibitory factor and interleukin-6 was dependent upon the endometrial stage and was decreased in treated monkeys. E and P receptor mRNAs increased significantly with mifepristone treatment compared with controls, another indication of delayed uterine staging.

CONCLUSION(S)

Mifepristone at 0.03 mg/kg/d had no antiovulatory effect but delayed development of the endometrium from the late to midsecretory phase. This study provides further evidence that endometrial maturation can be altered without affecting ovarian cyclicity.

Contraceptive efficacy of daily administration of 0.5 mg mifepristone

The antiprogestin mifepristone has shown potential to be used as a contraceptive. If 200 mg mifepristone is administered immediately after ovulation, the endometrium shows sufficient impairment of secretory development to prevent implantation. Low daily doses of mifepristone have been shown to reduce several of the local factors regarded as crucial for implantation in human endometrium. To find out if this regimen is sufficient to prevent pregnancy, 32 women were recruited for a study where 0.5 mg mifepristone was administered daily. A total of 141 cycles were studied. Five pregnancies occurred, which was significantly less than if no contraceptive method had been used. However, the dose chosen did not seem sufficient to act as a contraceptive although it is probably not possible to increase the dose without disturbing ovulation and bleeding pattern.

Contraceptive efficacy of low doses of mifepristone

OBJECTIVE

To determine whether a 5-mg dose of mifepristone is sufficient to prevent pregnancy.

DESIGN

Clinical study.

SETTING

Academic research center.

SUBJECT(S)

Healthy, fertile, sexually active female volunteers.

INTERVENTION

Volunteers received a 5-mg dose of mifepristone once weekly, starting on cycle day 2, for up to 6 months. This was their only contraceptive method.

MAIN OUTCOME MEASURE(S)

Number of pregnancies.

RESULT(S)

The treatment resulted in a significant decrease in pregnancy rate without affecting the menstrual cycle or causing disturbing side effects.

CONCLUSION(S)

A low dose of mifepristone, which does not inhibit ovulation, reduces fertility significantly by affecting the endometrium. However, the contraceptive effect needs to be improved for the drug to compete with other contraceptive methods.

Generation and characterization of a polyclonal antipeptide antibody to human glycodelin

OBJECTIVE

To develop and characterize an antiglycodelin antibody using a 15-amino acid synthetic peptide as antigen, derived from the sequence of human glycodelin.

DESIGN

We have developed a chicken antiglycodelin-derived peptide antibody and have characterized the antibody with the use of endometrial and ovarian cell lines. The antibody was also tested for its ability to detect glycodelin by ELISA assay, immunocytochemistry, and by Western blot.

SETTING

Various cell lines, cell culture medium, and amniotic fluid were used in the experiments.

PATIENT(S)

Amniotic fluid was collected from pregnant patients in their first trimester of pregnancy.

INTERVENTION(S)

No intervention.

MAIN OUTCOME MEASURE(S)

Detection of glycodelin.

RESULT(S)

The cell lines RL95-2 (human endometrial carcinoma cells), OVCAR-3 (human ovarian adenocarcinoma cells), HeLa (human cervical epitheloid carcinoma cells), and EM42-D (human endometrial epithelial cells) reacted with the antibody, indicating the presence of glycodelin. A specific 45-kd protein representing glycodelin was detected by Western blot in the amniotic fluid.

CONCLUSION(S)

Antipeptide antibodies can be successfully used to detect and quantify the presence of glycodelin in cells and fluids.

Antiprogestin pharmacodynamics, pharmacokinetics, and metabolism: implications for their long-term use

Antiprogestins represent a relatively new and promising class of therapeutic agents that could have significant impact on human health and reproduction. In the present work, the pharmacodynamics, pharmacokinetics, and metabolism of mifepristone (MIF), lilopristone (LIL), and onapristone (ONA) in humans are reviewed, and characteristics bearing important clinical implications are discussed. Although MIF has gained notoriety as an "abortion pill," antiprogestins may more importantly prove effective in the treatment of endometriosis, uterine leiomyoma, meningioma, cancers of the breast and prostate, and as contraceptive agents. MIF pharmacokinetics display nonlinearities associated with saturable plasma protein (alpha 1-acid glycoprotein, AAG) binding and characterized by lack of dose dependency for parent drug plasma concentrations (for doses greater than 100 mg) and a zero-order phase of elimination. LIL and ONA pharmacokinetics are less well characterized but ONA does not appear to bind AAG and displays a much shorter t1/2 than the other agents. The three antiprogestins are substrates of cytochrome P450 (CYP) 3A4, an enzyme exceedingly important in human xenobiotic metabolism. Even more implicative of likely drug-drug interactions subsequent to their long-term administration are recent data from our laboratory indicating that they inactivate CYP3A4 in a cofactor- and time-dependent manner, suggesting that complexation and induction of the enzyme may occur in vivo via protein stabilization. Moreover, it has been demonstrated that MIF increases CYP3A4 mRNA levels in human hepatocytes in primary culture, indicative of message stabilization and/or transcriptional activation of CYP3A4 expression. Finally, MIF has also been shown to inhibit P-glycoprotein function. Whether LIL and ONA share these latter two characteristics with MIF has not yet been determined but they illustrate properties that, in addition to diminished antiglucocorticoid activities and altered pharmacokinetic characteristics, warrant consideration during the development of these and never antiprogestational agents.

Effect of once weekly administration of mifepristone on ovarian function in normal women

The effects of mifepristone on ovarian function during a once weekly oral administration regimen were studied in nine healthy women. Each received 25 mg mifepristone on cycle days 3, 10, 17, and 24. Ovulation, as documented by hormonal measurements and ultrasonography, was inhibited during treatment in five subjects, with a midcycle surge of luteinizing hormone and ovulation occurring 6-18 days after the last pill was administered in four of the five subjects. These five treatment cycles were prolonged 9-26 days. The other four subjects had normal cycles as judged by serum hormone levels, ultrasonography, and cycle length. All nine subjects had delayed endometrial growth as indicated by ultrasonography. There was a significant correlation between concentrations of serum mifepristone (10 h and 58 h) and alpha 1-acid glycoprotein, the protein to which mifepristone binds in circulation. Response to mifepristone did not depend on its circulating levels. We conclude that once weekly administration of 25 mg mifepristone can interfere with normal follicular development and function, but the inhibition of ovulation was inconsistent.

Anti-implantation activity of luteal phase mifepristone administration is not mimicked by prostaglandin synthesis inhibitor or prostaglandin analogue in the rhesus monkey

The use of mifepristone as an anti-implantation agent in the primate has been explored in the rhesus monkey with two specific aims: (i) to determine the contraceptive efficacy of very low-dose mifepristone administered on mated cycle days 16, 17, and 18; and (ii) to test the hypothesis that alteration in endometrial prostaglandin milieu by using either prostaglandin analogue or prostaglandin synthesis inhibitor can intervene the antifertility effect induced by mifepristone. Thirty female monkeys were randomly assigned to one of the six treatment groups. Five monkeys in the control group (group 1) were subjected to mating during cycle days 8-22. Four out of five monkeys became pregnant in the first mated cycle (80%) with detection of serum mCG by 12.7 +/- 1.5 days after ovulation. In group 2, 12 mated cycles were studied in five monkeys, mifepristone [RU486, 2 mg/day/animal, s.c. in 1 ml vehicle (1:4, benzyl benzoate:olive oil, v/v)] was given on cycle days 16, 17, and 18. In this group, no pregnancy was observed, thus providing complete pregnancy protection. Though there was an apparent extension of treatment cycle lengths in five cases with no incidence of inter-menstrual bleeding or spotting, there were no significant changes in serum estradiol (E) and progesterone (P). In group 3, four monkeys received prostaglandin (PG) synthesis inhibitor, diclofenac sodium (D, 25 mg/day/animal, i.m.) on cycle days 16, 17, and 18 in seven ovulatory menstrual cycles. Four of these cycles (57%) resulted in normal pregnancies; however, mCG detection (16.8 +/- 1.2 days after ovulation) was significantly (p < 0.05) delayed as compared to group 1. In group 4, four monkeys received 100 micrograms misoprostol (M), a PGE1 analogue, by gavage on mated cycle days 16, 17, and 18. Four pregnancies occurred in five treatment cycles (80%) with normal profiles of serum E and Pi mCG was first detected 13.2 +/- 1.7 days after ovulation. In group 5, seven monkeys received same dosages of RU486 and D on mated cycle days 16, 17, and 18. One hundred percent pregnancy protection was observed with luteal phase lengthening in eight treatment cycles but with unaltered E and P profiles. In group 6, five monkeys in nine treatment cycles received same dosages of RU486 and M on mated cycle days 16, 17, and 18. One pregnancy occurred; evaluation of E and P levels showed that the drug was given in the preovulatory period, which delayed ovulation and implantation, as mCG was detected 19 days post-ovulation. A delay in vaginal bleeding was observed in four treatment cycles with unaltered E and P profiles. Low-dose mifepristone appears to be a potential candidate for luteal phase and post-coital emergency contraception. However, the hypothesis that altered endometrial prostaglandin milieu may be responsible for mediating the anti-implantation effect of RU486 does not appear to be tenable based on our results in the rhesus monkey.

RU486 (mifepristone): mechanisms of action and clinical uses

RU486 (mifepristone) has proved to be a remarkably active antiprogesterone and antiglucocorticosteroid agent in human beings. The mechanism of action involves the intracellular receptors of the antagonized hormones (progesterone and glucocorticosteroids). At the molecular level, the most important features are high binding affinity to the receptor, interaction of the phenylaminodimethyl group in the 11 beta-position with a specific region of the receptor binding pocket, and RU486-induced transconformation differences in the ligand-binding domain. These particularities have consequences at different steps of the receptor function as compared with agonists. However, the reasoning cannot be limited to the RU486-receptor interaction, and, for instance, there is the possibility of a switch from antagonistic property to agonist activity, depending on the intervention of other signaling pathways. It would be desirable to have derivatives with only one of the two antagonistic properties (antiprogestin, antiglucocorticosteroid) in spite of similarities between steroid structures, receptors involved, and responsive machineries in target cells. Clinically, the RU486-plus-prostaglandin method is ready to be used on a large scale and is close to being as convenient and safe as any medical method of abortion may be. The early use of RU486 as a contragestive as soon as a woman fears a pregnancy she does not want will help to defuse the abortion issue. Research should now be conducted to define an efficient and convenient contraceptive method with RU486 or other antiprogestins. The usefulness of RU486 for obstetric indications, including facilitation of difficult delivery, has to be assessed rapidly. Gynecologic trials, particularly in leiomyomata, should be systemically continued. The very preliminary results obtained with tumors, including breast cancers, indicate that further studies are necessary.

Contraception with anti-progesterone

Anti-progesterones have potential as contraceptives, acting either by the inhibition of ovulation or the inhibition of endometrial development. Clinical studies have shown that once-a-month treatment with Mifepristone in the early luteal phase is an effective contraceptive method, and that emergency post-coital contraception with Mifepristone is at least as effective as other methods currently used. Recent studies indicate that the endometrium is more susceptible to Mifepristone than are the hypothalamic and pituitary regions, and it may therefore be possible to develop a new contraceptive method based on low daily or once-weekly doses of Mifepristone that does not influence ovarian function.