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PubMed2000

The antiovulatory potential of progesterone antagonists correlates with a down-regulation of progesterone receptors in the hypothalamus, pituitary and ovaries.

These studies analyze the regulation of progesterone receptors (PRs) in central and peripheral tissues with the aim of further understanding mechanistically the inhibition of ovulation by progesterone antagonists (PA). Therefore, it was of interest to investigate the influence of the progesterone receptor antagonist, Onapristone (ON), on PRs in the ovary, pituitary (PT), and hypothalamus (HYP), since ON effectively inhibits ovulation in rats. For this study PMSG/hCG-primed immature and adult female rats were treated with ON. Immunohistochemistry was used for the detection of PRs. Progesterone (P4) and estradiol (E2) levels were determined by RIA. PR expression in the ovaries of immature rats was not detectable until after hCG administration. In these animals, ON caused a reduction in the staining intensity of PR in the tertiary follicles at the time when the preovulatory P4-surge was inhibited (6 h post hCG). Adult rats treated for 15 days with ON showed a decreased PR expression in PT and HYP. At this time (proestrus, 7 p.m.) the P4 and E2 levels are significantly lowered. These results suggest that after treatment with ON the expression of PR is reduced in the ovary, PT and HYP. The regulation of PR in the ovary seems to be less dependent on estrogens than on LH. Thus, it is conceivable that the reduced PR expression after ON treatment may be a result of decreased LH sensitivity in the ovary. In the pituitary and hypothalamus, PR expression is stimulated by estrogens and progesterone, and therefore the fall in the P4 and E2 levels in ON-treated animals may be responsible for the reduced PR expression in PT and HYP, and may contribute to the antiovulatory effect of ON. We therefore conclude that the mechanism of the antiovulatory potency of progesterone antagonists is based on a reduced preovulatory P4-production and PR expression in the ovary and also on the down-regulation of PR in the anterior pituitary and hypothalamus.

Animals↗
PubMed1991

Differences in the binding mechanism of RU486 and progesterone to the progesterone receptor.

The binding mechanism of the antagonist RU486 to the progesterone receptor was compared with that of the agonists progesterone and R5020. Both progesterone and RU486 bound to the receptor with a Hill coefficient of 1.2, indicating the binding of each ligand is positive cooperative. However, when each ligand was used to compete with [3H]progesterone for binding to the receptor at receptor concentrations near 8 nM, at which the receptor is likely a dimer, the competition curve for RU486 was significantly steeper than the curves for progesterone and R5020 (p less than 0.001). This indicated that a difference in the binding mechanism of RU486 and progesterone can be detected when both ligands are present. In contrast, at receptor concentrations near 1 nM, at which the receptor is likely a monomer, the competition curves for all three ligands were indistinguishable (p = 0.915). These results indicate that RU486 and agonists have different binding mechanisms for the receptor and further suggest that this difference may be related to site-site interactions within the receptor.

Animals↗
PubMed1982

Oestrogen and progesterone receptors in chick oviduct chromatin after administration of oestradiol, progesterone or anti-oestrogen.

Oestrogen-primed and withdrawn chicks were injected with oestradiol benzoate, progesterone, and/or the anti-oestrogens tamoxifen and 4-hydroxytamoxifen. Oestrogen receptors were studied in oviduct chromatin solubilized by mild digestion of purified nuclei with micrococcal nuclease. After a single injection of oestradiol benzoate, ultracentrifugation on sucrose gradients of chromatin extracts labelled with [3H]-oestradiol showed two peaks of oestradiol binding sites, sedimenting at 13--14 S and 7--8 S. After repeated injections of oestradiol benzoate, the 13--14 S peak increased more than the 7--8 S peak. After injection of anti-oestrogen alone or together with oestradiol benzoate, no [3H]oestradiol-binding or 4-hydroxy[3H]tamoxifen-binding peaks were detected in the chromatin. Injection of progesterone also produced an increase of the 13--14 S and 7--8 S chromatin oestradiol receptor. Progesterone receptor could only by detected in chromatin early after progesterone administration, and it sedimented in density gradients with the 12 S mononucleosome fraction. Tamoxifen injected together with progesterone gave higher levels of 13--14 S oestrogen binding sites than did progesterone alone. The presence of a 13--14 S peak of oestrogen binding sites in hormonal situations which promote a biological response in the chick oviduct, and the absence of this peak after administration of anti-oestrogens, suggest that this subfraction of chromatin contains elements involved in gene regulation.

Animals↗
PubMed2006

Progesterone regulates HLA-G gene expression through a novel progesterone response element.

BACKGROUND: We have previously demonstrated that progesterone has a stimulatory effect on HLA-G gene expression. Because this effect was abolished by the anti-progestin, RU486, we hypothesize that this effect is through receptor-mediated up-regulation of the HLA-G gene. The objective of this study was to explore the molecular mechanisms of this effect. METHODS: The transient transfection of a chloramphenicol acetyltransferase (CAT) construct containing a fragment of the HLA-G gene promoter into the JEG-3 choriocarcinoma cell line was performed. An electrophoretic mobility shift assay (EMSA) and a DNA fragment-binding enzyme-linked immunosorbent assay (ELISA) were carried out to locate a specific progesterone response element (PRE) in the HLA-G gene promoter region. RESULTS: Progesterone treatment of JEG-3 cells transfected with the HLA-G gene promoter-CAT construct resulted in an increase of CAT synthesis, whereas RU486 blocked this transcriptional activation. A novel PRE-binding site sequence, with 60% homology to that of wild-type mouse mammary tumour virus (MMTV) PRE, was discovered in this region. CONCLUSION: The effect of progesterone on HLA-G gene expression is through progesterone receptor (PR) activation, followed by binding to a novel PRE in the HLA-G promoter region. Therefore, one of the mechanisms of immunomodulation by progesterone during pregnancy may be through the regulation of HLA-G gene expression via this novel PRE.

Breast Neoplasms↗
PubMed1992

Immunohistochemical localization of estradiol, progesterone, and progesterone receptor in human salivary glands and salivary adenoid cystic carcinomas.

Immunohistochemical analyses of estradiol, progesterone and progesterone receptor were carried out in human salivary gland and salivary adenoid cystic carcinoma. Immunoreactivity to estradiol and progesterone was found in cytoplasm of the cells of the excretory duct system within normal salivary glands, whereas the progesterone receptor was restricted to nuclei of the cells where both sex steroids were positive. In addition, we demonstrated the presence of both sex steroids and the receptor for progesterone in salivary adenoid cystic carcinomas. These data indicate that the human salivary gland is one of the target tissues of estrogen. This also suggests the good possibility that tumors which express progesterone receptors will respond to endocrine therapy.

Adult↗
PubMed1986

Circulating progesterone, progesterone-binding proteins and oestradiol-17 beta concentrations in the pregnant Cape porcupine, Hystrix africaeaustralis.

Circulating concentrations of progesterone, progesterone-binding plasma proteins (PBPP) and oestradiol-17 beta in pregnant porcupines remained relatively low until Days 25-30 post coitum. Progesterone values peaked (102-180 ng/ml; N = 3) 42-60 days post coitum and the rapid increase in oestradiol-17 beta concentrations approximated that of progesterone with peak values (170-210 pg/ml) being attained 60-85 days post coitum. The pattern of PBPP synthesis, as suggested by circulating concentrations, was closely related to that of plasma progesterone, with values remaining low (less than 20 pmol/ml) until Day 31 post coitum, reaching peak levels at Days 50-56 and Days 73-77 post coitum. The production of PBPP during pregnancy is, as in related New World hystricomorph species, considered to be a mechanism which facilitates a reduction in the rate of progesterone metabolism during pregnancy.

Alpha-Globulins↗
PubMed1989

[Experimental studies on the antitumor effect of progesterone and enhancement of the therapeutic effect of anticancer drugs by progesterone--from the aspect of zinc metabolism].

Since zinc is essential for the proliferation of tumor cells, the growth of tumor cells is suppressed in the zinc deficient condition. Thus, administration of progesterone, which decreases zinc uptake of tumor cells, to tumor bearing rats may inhibit the tumor growth. From this aspect, the antitumor effect of progesterone alone, or in combination with various anticancer drugs was investigated in the rats bearing Yoshida sarcoma (YS) or ascites hepatoma 109A (AH 109 A). In YS bearing rats, a significant inhibition of the tumor growth in size was observed by progesterone, and a slight inhibition of the tumor growth in AH 109 A bearing rats. A decreased zinc content of YS cells was also observed in YS bearing rats given progesterone in comparison with that of control rats. In combination of progesterone and anticancer drugs, the antitumor effect of methotrexate or vincristine was markedly enhanced by progesterone in YS bearing rats.

Animals↗
PubMed1988

Decreased progesterone binding and attenuated progesterone action in cultured human breast carcinoma cells treated with epidermal growth factor.

Specific progesterone binding by cultured human breast carcinoma T47D, MCF-7, and ZR75-1 cells was decreased 25-40% by epidermal growth factor (EGF), with a 50% effective dose of 0.1 nM EGF. Studies with the soluble and particulate fractions prepared after homogenization of T47D cells grown in glass roller bottles revealed equivalent EGF-induced decreases in progesterone binding to receptors in both fractions. Equilibrium progesterone binding studies with these soluble and particulate fractions revealed that EGF decreased the receptor number, but had no effect on affinity. With cells grown adherent to plastic dishes, EGF treatment induced a greater decrease in binding to receptors recovered in the particulate fraction, than to receptors recovered in the soluble fraction. The decrease in progesterone binding induced by 20 nM EGF was maximal after 2 min of cellular EGF treatment for receptors recovered in the soluble fraction, but was only half-maximal after 15 min for receptors recovered in the particulate fraction. Decreased progesterone binding persisted for at least 8 days in cells cultured with 1 nM EGF. Either insulin or EGF stimulated T47D cell proliferation by two- to threefold with a 50% effective dose of 100 nM for insulin and 0.1 nM for EGF. The progestin, R5020, decreased T47D cell growth by 30% with a 50% effective dose of 1 nM. Either EGF or insulin antagonized the inhibitory effect of R5020 on cell reproduction, but progestins did not antagonize the growth stimulatory response of cells to EGF. Progestins increased the number of EGF receptors within 12 h of their addition to T47D cells, but this response was lost after 6 days. These data show that EGF or progesterone can regulate the receptor number of the other, but for cell reproduction, the effect of EGF is dominant over that of progestins.

Animals↗
PubMed2004

Comparative bioavailability study in dogs of a self-emulsifying formulation of progesterone presented in a pellet and liquid form compared with an aqueous suspension of progesterone.

A pellet formulation of progesterone in a self-emulsifying system (SES) was prepared by the process of extrusion/spheronization to provide a good in vitro drug release (100% within 30 min, T(50%) at 13 min). A three-way randomized crossover study was performed in six fasted male beagle dogs with these pellets and the same SES liquid formulation, both contained in a hard shell capsule, and an aqueous suspension. The same dose of progesterone (16 mg) in pellets and in the SES liquid formulation resulted in similar AUC, C(max) and T(max) values, estimated from progesterone plasma levels by (125)I radioimmunoassay. Although the maximum absorption was slightly retarded (0.5 to 1 h) by SES (pellets and liquid), AUC and C(max) were approximately seven and nine times greater then those obtained when an aqueous suspension formulation of the same dose of progesterone was administered to the same dogs. These results showed that it was possible to improve the bioavailability of the poorly soluble, poorly permeable progesterone when administered in SES. Moreover, presenting the progesterone in the form of a pellet did not prevent the release of the drug in vivo. These data demonstrate the utility of extrusion/spheronization in delivering a nonaqueous system in a novel solid dosage form.

Animals↗
PubMed1988

Progesterone profiles in luteal phase defect cycles and outcome of progesterone treatment in patients with recurrent spontaneous abortion.

The existence of luteal phase defect has been the focus of much debate, mainly because of inconsistencies in its diagnosis and management. This study was performed to compare progesterone profiles in women with luteal phase defect with those of women with normal cycles and to establish a discriminatory level of serum progesterone that may aid in the diagnosis of this condition. Compared with patients with luteal phase defect cycles, women with normal cycles produced significantly more progesterone in the luteal phase. The serum progesterone level (less than or equal to 21 nmol/L) was the optimal discriminatory level between luteal phase defect and normal cycles and provided a diagnostic test with 70% sensitivity and 71% specificity. In women with recurrent abortion, the incidence of luteal phase defect was 40%, but with treatment 81% of pregnancies were successful. The findings in this study support the existence of luteal phase defect as a clinically significant entity in recurrent first-trimester spontaneous abortion and one that can be treated successfully with the administration of progesterone. The histologic diagnosis of luteal phase defect may also be confirmed with serum progesterone.

Abortion, Habitual↗
PubMed1988

Acquisition of estrogen-dependent progesterone receptors by normal mouse mammary gland. Ontogeny of mammary progesterone receptors.

Progesterone is known to stimulate cell proliferation of normal and neoplastic rodent mammary tissues. Recently we have observed that while progesterone is highly effective in sexually mature mice, no significant effect of progesterone can be demonstrated in immature, pubertal mammary gland. In the case of the adult gland, the mitogenic effects of progesterone appear to be related to the presence of E-dependent progesterone receptors (PgR). By contrast, immature mammary glands lack E-dependent PgR. The purpose of the present studies was to study the ontogeny of E-dependent PgR and the factors that lead to the acquisition of responsiveness to progesterone. The results obtained demonstrate that E-dependent PgR are first detectable at 7 weeks of age. Analysis of changes occurring in the mammary gland around this time indicate that E-dependent PgR are not acquired until the pubertal mammary epithelial growth phase has occurred. Furthermore both the growth phase and acquisition of PgR are dependent upon the presence of the ovaries. Analysis of concentration and subcellular distribution of both PgR and estrogen receptors indicate that there are no differences between pubertal and adult mice that could account for the absence of this estrogenic response and lack of E-dependent PgR in immature mammary gland.

Animals↗
PubMed1982

Effects of prostaglandins, dibutyryl cAMP, LHRH, estrogens, progesterone, and potassium on output of prostaglandin F2 alpha, 13, 14-dihydro-15-keto-prostaglandin F2 alpha, hCG, estradiol, and progesterone by placental minces.

In order to compare the endocrine response of placental minces to luteinizing hormone releasing hormone (LHRH) and dibutyryl cAMP (dbcAMP) and to screen for effects of potential stimulatory and inhibitory substances, the simultaneous outputs of PGF2 alpha, 13, 14-dihydro-15-keto-prostaglandin F2 alpha (PGFM), progesterone, 17 beta-estradiol, and hCG were evaluated during a 4 hour incubation in 5 placentas. The output of hCG was highest for 12-week placentas, intermediate for a 16 week placenta, and lowest for term placentas. The output of 17 beta-estradiol by 12 and 16 week placentas in the presence of 30 microM dehydroepian-drosterone sulfate (DHEAS) was greater than that by term placentas. Progesterone output was apparently independent of gestational age although some variation between 12-week placentas was demonstrated. Output of PGF2 alpha was lower in 12 and 16-week placentas than in term placentas and that of PGFM was lower in 12-week placentas than in term placentas. LHRH (100 nM) produced stimulation of PGF2 alpha output (P less than .005) and a trend toward inhibition of progesterone output (which failed to achieve statistical significance) but no stimulation of hCG under these conditions. Stimulation of the outputs of hCG (P less than .005) and PGF2 alpha (P less than .001) and inhibition of that of progesterone (P less than .005) was produced by 20 mM dbcAMP. DHEAS inhibited output of progesterone (P less than .01) and PGF2 alpha (P less than .01). There were no effects of potassium, estrogens, progesterone, or prostaglandins on output of any measured substance.

Bucladesine↗
PubMed1985

Fertility regulation in nursing women: VIII. Progesterone plasma levels and contraceptive efficacy of a progesterone-releasing vaginal ring.

The objectives of this trial were to test the contraceptive efficacy and measure progesterone plasma levels of women using progesterone-releasing rings during lactation. Two types of rings delivering an average of about 5 mg or 10 mg of progesterone per day were tested in 128 healthy nursing women. A control group was formed by 127 Copper T users. Rings were inserted at day 60 postpartum and replaced every 3 months with a new one. Initially progesterone plasma levels were around 10 nmol/l and 15 nmol/l for rings releasing 5 and 10 mg per day, respectively, and decreased slightly after 30 days. Levels observed in subsequent segments of use approximated those of the first segment. These levels are within the range shown to inhibit fertility in lactating women. One pregnancy was diagnosed in 739 woman-months of progesterone ring use, and none occurred in 794 woman-months of Copper T use, which contrasts with the high incidence of pregnancy in a group of untreated nursing women where 19 pregnancies resulted during 677 woman-months. No deleterious effects were detected lactation and infant growth or maternal and infant health. It is concluded that the vaginal rings releasing progesterone are a suitable contraceptive method for lactating women.

Clinical Trials as Topic↗
PubMed1976

A computer simulation of the effect of injected anti-progesterone on progesterone levels of pregnant rats.

Antibodies to progesterone injected into pregnant rats, provoke abortion if the concentration of the biologically active progesterone is reduced to a critical level. By stimulating the biological experiments in the computer we describe the time dependent changes of this progesterone fraction, as a function of the initial concentration of progesterone and of the anti-progesterone injected. Results obtained can be used to aid interpreting the findings of the biological studies and to calculate the concentration of anti-progesterone required to provoke abortion.

Abortion, Induced↗
PubMed2004

Investigation of product quality between extemporaneously compounded progesterone vaginal suppositories and an approved progesterone vaginal gel.

The purpose of this investigation was to compare quality parameters, including product appearance, content uniformity, pH, weight uniformity, microbial limit testing and preservative effectiveness testing on extemporaneously compounded progesterone vaginal suppositories obtained from 10 randomly chosen compounding pharmacies (90 suppositories each) across the United States, to the Food and Drug Administration (FDA) approved prescription progesterone gel product (Prochieve/Crinone) which is manufactured in a cGMP regulated facility. The content uniformity and pH were determined using qualified methods. The microbial limits testing and preservative effectiveness testing were conducted according to compendial methods. Only one pharmacy provided suppositories that were all within the potency limits required for the prescription progesterone gel product. The other pharmacies provided at least some suppositories where progesterone content was either subpotent or superpotent for progesterone. The pH of most of the compounded suppository products was in the range of 4.22 to 7.68 with a median of 6.30 (normal vaginal pH is <5), whereas the gel product was 2.80. For compounded product from one of the pharmacies, microbial limits testing indicated CDC group IVC-2 and Comamonas acidovorans were detected. This data indicates that pharmacy compounded delivery systems for progesterone should be used with caution.

Chemistry, Pharmaceutical↗
PubMed1969

Interaction of estrogen and progesterone in chick oviduct development. II. Effects of estrogen and progesterone on tubular gland cell function.

The effects of estrogen and progesterone on the function of chick oviduct tubular gland cells have been studied. Such function, as measured by the increase in specific cell products such as lysozyme and ovalbumin, requires the continuous presence of estrogen or progesterone. Withdrawal of hormone results in a rapid cessation of function and an involution of the oviduct accompanied by rapid decreases in total weight, lysozyme, and RNA. During such involution, tubular gland cells per se persist, as evidenced by a lack of comparable decrease in total DNA content and by histological demonstration of tubular gland cells. When estrogen administration is reinstituted, preexisting tubular gland cells rapidly synthesize ovalbumin and lysozyme without requiring new DNA synthesis. Administration of progesterone also stimulates the function of such cells. Furthermore, the effects of estrogen and progesterone are synergistic on the synthesis of lysozyme and ovalbumin, whereas progesterone antagonizes the estrogen-evoked formation of tubular gland cells. It is suggested that such complex interactions of estrogen and progesterone on oviduct development and function result from differences in responsiveness of the various cell types present in the tissue.

Animals↗
PubMed1996

Luteal support after in-vitro fertilization: Crinone 8%, a sustained release vaginal progesterone gel, versus Utrogestan, an oral micronized progesterone.

Two progesterone presentations, a vaginal application of 90 mg progesterone per day (Crinone) or 300 mg progesterone administered orally (Utrogestan), were compared for luteal phase support of patients undergoing an in-vitro fertilization (IVF) procedure. A total of 283 patients were randomly allocated to either treatment. The treatment started within 24 h after the embryo transfer procedure and continued until day 30 in cases of implantation. Efficacy was assessed using the pregnancy and delivery rates. Safety was assessed through specific symptoms and usual safety monitoring. The pregnancy rates per transfer were not significantly different in the Crinone and Utrogestan groups at days 12 (Crinone 35.3%, Utrogestan 29.9%, P = 0.55), 30 (Crinone 28.5%, Utrogestan 25.0%, P = 0.61) and 90 (Crinone 25.9%, Utrogestan 22.9%, P = 0.69). No differences in the spontaneous abortion rates were seen thereafter. The delivery rates (number of deliveries per patient; Crinone 23.0%, Utrogestan 22.2%, P = 1.00), as well as the ratio of newborn babies per embryo transferred (Crinone 11.7%, Utrogestan 11.1%, P = 0.91), were not significantly different. Safety parameters were similar in both groups, except for drowsiness, which was more significantly frequent in the oral progesterone group than in the Crinone group at all time points. No serious adverse events were recorded in this study. The fact that Crinone matches the efficacy of the larger doses of progesterone used orally reflects an advantage of the transvaginal route of administration which avoids the metabolic inactivation of progesterone during its first liver pass.

Administration, Oral↗
PubMed1988

Luteal progesterone synthesis and high-density lipoprotein. Evidence implicating a pronase-sensitive HDL-binding site in the mechanism by which HDL supports luteal progesterone synthesis.

We have shown previously that corpus luteum cells isolated from the superovulated ovaries of rats treated with 4-amino-pyrazolo[3,4-d]pyrimidine constitute a suitable experimental system by which to investigate the mechanism in which plasma high-density lipoprotein (HDL) plays a role in luteal cellular progesterone synthesis. In the present study, the rate of luteal cellular progesterone synthesis was shown to be stimulated by 125I-labelled HDL up to about 70% of the rate achieved in the presence of native HDL. The concentration of HDL needed for half-maximal stimulation of progesterone synthesis in the presence of lutropin was not significantly different irrespective of whether radioiodinated HDL or unlabelled HDL was used. Experimental conditions for studying the binding of 125I-labelled HDL to isolated luteal cells have been defined and cellular binding affinity and binding capacity have been measured. Exposure of the luteal cells to pronase virtually abolished their capacity to bind 125I-HDL and made them unable to respond to added HDL by increasing their rate of progesterone synthesis in the presence of lutropin. Control experiments showed this effect of pronase on cellular progesterone synthesis not to be due to destruction of cellular lutropin receptors, nor to general cellular damage. This evidence supports the view that luteal cellular binding of HDL is part of the mechanism by which HDL acts in luteal progesterone synthesis. Cellular binding capacity and affinity for 125I-labelled HDL were the same irrespective of whether or not lutropin was present during incubation. Furthermore, the binding capacity and affinity of cells from the ovaries of rats not treated with 4-amino-pyrazolo[3,4-d]pyrimidine were the same as in luteal cells isolated from rats that had been treated.

Adenine↗