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PubMed1993

Specific binding of progesterone receptor to progesterone-responsive elements does not require prior dimerization.

Steroid-hormone receptors undergo, prior to binding to DNA, a hormone-dependent dimerization. It is generally accepted that this dimerization is indispensable for the high-affinity binding of hormone receptor to hormone-responsive elements. Using a progesterone-receptor mutant with the complete steroid-binding domain deleted (positions 663-930), with or without the epitope required for binding the monoclonal antibody Let 126, we have shown that this receptor species was unable to undergo dimerization in solution. However, this mutant retained a high affinity (60-70% of the affinity of the wild-type receptor) for the progesterone-responsive elements of the mouse-mammary-tumor-virus long-terminal-repeat promoter and for a consensus palindromic progesterone-responsive element, as measured by both DNase-I protection experiments and gel-shift experiments. This mutant also increased gene transcription. Thus, at least in the case of the progesterone receptor, prior dimerization is dispensable for receptor binding to regulatory DNA elements and for subsequent transcription activation.

Animals↗

PubMed1987

Saliva oestriol, oestradiol, oestrone and progesterone levels in pregnancy: spontaneous labour at term is preceded by a rise in the saliva oestriol:progesterone ratio.

Saliva steroid levels reflect the unbound unconjugated (free, biologically active) plasma hormone levels. Saliva oestriol (E3), oestradiol (E2), oestrone (E1) and progesterone levels were estimated by radioimmunoassay in saliva samples obtained twice a week from 18 weeks gestation until 38 days before delivery and then daily until the spontaneous onset of labour at term from 20 normal pregnant women. The overall percentage increases in the median concentrations of E3, E2, E1 and progesterone were 718, 370, 80 and 214%, respectively, in the last 20 weeks and 149, 82, 24 and 41%, respectively, in the last 6 weeks of pregnancy. The median E3:progesterone ratio rose slowly from 0.65 at 20 weeks before delivery to 1.0 at 5 weeks before delivery and then rapidly to 1.65 one day before the spontaneous onset of labour. There was an increase in the E3:progesterone ratio from less than 1 to greater than 1 before labour in every subject.

Estradiol↗

PubMed1990

Binding of progesterone to nerve cell membranes of rat brain using progesterone conjugated to 125I-bovine serum albumin as a ligand.

Radioiodinated bovine serum albumin conjugated to progesterone was used as a probe to examine binding parameters of steroids to membrane preparations from rat brain tissue. The binding of 11 alpha-hydroxyprogesterone-11-hemisuccinate-125I-bovine serum albumin conjugate reached saturation after 30 min of incubation at 5 degrees C. Several bovine serum albumin-conjugated steroids were then tested for competition displacement studies. Among these steroid conjugates, the bovine serum albumin conjugate at position 3 of progesterone had the highest affinity, with an estimated inhibition constant of 28.5 +/- 2.1 nM (n = 3), whereas bovine serum albumin itself and the 17 beta-estradiol 6-(O-carboxy-methyl)oxime-bovine serum albumin conjugate showed no specific displacement. In addition, the binding sites were localized in an axolemma-enriched fraction of rat brainstem. Specific binding was obtained in tissues from cerebral cortex, brainstem, cerebellum, corpus striatum, and hypothalamus, but little or no binding occurred in uterus, ovary, liver, and spleen. The present data indicate that progesterone-125I-bovine serum albumin conjugate can be used as a ligand to study progesterone-membrane receptor interactions.

Animals↗

PubMed2002

Progesterone receptors--animal models and cell signalling in breast cancer. Diverse activation pathways for the progesterone receptor: possible implications for breast biology and cancer.

Progesterone and estradiol, and their nuclear receptors, play essential roles in the physiology of the reproductive tract, the mammary gland and the nervous system. Estrogens have traditionally been considered associated with an increased risk of breast cancer. There is, however, compelling evidence that progesterone plays an important role in breast cell proliferation and cancer. Herein, we review the possible role of progestins and the progesterone receptor-associated signaling pathways in the development of breast cancer, as well as the therapeutic possibilities arising from our growing knowledge of the activation of the progesterone receptor by other proliferative mechanisms.

Animals↗

PubMed1981

Progesterone and insulin-resistance: studies of progesterone action on glucose transport, lipogenesis and lipolysis in isolated fat cells of the female rat.

The effects of progesterone on isolated rat adipocytes were studied in vitro during various steps of glucose metabolism, transport, lipogenesis and lipolysis. Progesterone decreased the phosphorylation of glucose into glucose-6-phosphate as assessed by measuring the uptake of 2-deoxyglucose but it had no effect on transmembrane transport of glucose as determined by measuring the entry of 3-0-methylglucose into the cell. As glucose phosphorylation is a rate-limiting step of the pentose-phosphate pathway, these data could explain the inhibition of lipogenesis and the enhancement of lipolysis observed when progesterone is present in incubation medium. Progesterone might thus modulate a regulatory step of glucose metabolism and antagonize insulin action in the fat cell.

Adipose Tissue↗

PubMed1983

Mammary uptake and metabolism of progesterone in goats and its effect on milk progesterone concentrations during the oestrous cycle and early pregnancy.

Following the observation that the concentration of progesterone in goats' milk differs appreciably according to the specificity of the antiserum used in a non-extraction (direct) radioimmunoassay, experiments were carried out to find an explanation for these results. Milk and plasma samples were collected during the oestrous cycle and during an equivalent period of pregnancy after a fertile mating. Samples were analyzed by a direct radioimmunoassay using two antisera, 18/3 which is highly specific for progesterone and 465/6 which is less specific, and by radioimmunoassay of fractions isolated by thin-layer chromatography (TLC). Values obtained for milk and plasma samples collected during the oestrous cycle and early pregnancy were similar, except that values for milk samples measured with antiserum 465/6 were higher in pregnancy compared to those obtained during the oestrous cycle. Values obtained for milk and plasma with antiserum 465/6 were significantly higher than those obtained with 18/3 (P less than 0.001). After TLC this difference was found to be due principally to the presence of compound(s) with chromatographic properties identical to 5-pregnanedione(s). A comparison of the concentration measured in arterial and mammary venous plasma and in milk showed that about 25% of progesterone (5.7 nmol/min) was extracted by the mammary gland, and that substantial amounts of immunoreactive metabolites of progesterone are secreted into milk with only small quantities being transferred into mammary vein plasma.

Animals↗

PubMed1976

Plasma progesterone concentrations in cows and steers after Repositol Progesterone treatment.

Repositol progesterone was injected intramuscularly into 4 steers and 17 postpartum cows at a dose of 2.2 mg/kg body weight. In steers the plasma progesterone concentration rose to 6.8 ng/ml 1 day postinjection and declined to a mean concentration of 2.1 ng/ml on days 3 and 4 postinjection. Postpartum, presumed anestrus, cows reached a lesser progesterone concentration of 2.9 ng/ml 1 day postinjection and then declined to a lower mean of .7 ng/ml on days 3 and 4 postinjection. These data suggest different rates of metabolism and/or excretion of progesterone by cows and steers.

Anestrus↗

PubMed2002

Autoimmune progesterone dermatitis manifested as erythema annulare centrifugum: Confirmation of progesterone sensitivity by in vitro interferon-gamma release.

Autoimmune progesterone dermatitis was manifested as deep-type erythema annulare centrifugum. Sensitivity to progesterone was studied in vivo by means of intradermal and patch tests, which revealed immediate-type and delayed-type hypersensitivity, respectively. Sensitivity to progesterone was further confirmed in vitro by results of an interferon-gamma release test, which imply a possible role for T(H)1-type cytokines in autoimmune progesterone dermatitis.

Adult↗

PubMed1990

[The applicability of a detection method independent of a laboratory for progesterone in the blood plasma of mares (Hygia progesterone test)].

A rapid progesterone assay for cow's milk was checked as to whether it was applicable to mares' blood plasma. The "Hygia Progesterone-Test" is an on-farm test which serves for qualitative analysis. It is generally unusable for mares' plasma but sufficiently precise only in cases of larger or smaller progesterone levels. In cases of moderate amounts of progesterone the test is imprecise. The test can be carried out quickly and easily, but the preparation of blood samples takes more time than preparation of milk samples. The test can be recommended for usage in veterinary practice only, but not for animal owners.

Animals↗

PubMed1990

The effect of progesterone and progesterone + estradiol on the morphology of the pineal gland in immature female pigs.

Pineal gland of the immature female pigs treated with progesterone and progesterone and estradiol simultaneously were investigated with light and electron microscopy. Both of the applied hormones influenced the structure of the pineal glands. Inhibitory effect of progesterone on the relative volume of mitochondria, granular vesicles and dense bodies of type one was observed. Administration of progesterone and estradiol simultaneously caused more complicated influence statistically significant increase of pinealocyte nuclei volume and at the same time significant decrease of mitochondria and granular vesicles.

Animals↗

PubMed1989

Induction of lactation in cattle with estradiol 17-beta and progesterone primed with progesterone.

Five parous non-pregnant, non-lactating cows were injected (sc) with progesterone (50 mg/day for 7 consecutive days) followed by estradiol (0.1 mg) plus progesterone (0.25 mg) per kg body wt/day on day 12 to 14 and with reserpine / 2 mg twice a day on day 19 to 22. All the 5 cows were successfully induced into lactation. Animals exhibiting estrus following hormonal therapy were artificially inseminated and one cow became pregnant and exhibited normal parturition. Jugular blood collected was used for estimation of progesterone by RIA technique and considerable individual variation was observed in progesterone concentration.

Animals↗

PubMed1988

[Effect of adrenocorticotropin on the progesterone level in the peripheral blood and on adrenal progesterone production in vitro in female silver foxes].

The plasma progesterone increased following a single injection of ACTH (3 ME/kg). The progesterone production was also increased by ACTH after incubation of adrenals in vitro. The data suggest that the adrenal glands of female silver foxes are capable not only of secreting progesterone, but also of responding to ACTH with a further increase in the progesterone secretion.

Adrenal Glands↗

PubMedDate not supplied

Progestins, progesterone receptor modulators, and progesterone antagonists change VEGF release of endometrial cells in culture.

The influences of the synthetic progestin, medroxyprogesterone acetate (MPA), the progesterone receptor modulator J867, and the antagonist ZK137316 were studied in vitro on isolated endometrial epithelial cells, as well as endometrial fibroblasts. We evaluated the expression of estrogen receptor alpha (ER) and the progesterone receptor (PR) by RT-PCR. ER and PR were strongly expressed in the fibroblasts and epithelial cells under treatment with 10(-8) M 17beta-estradiol (E(2)). Treatment with 10(-6) M J867 or ZK137316 upregulated the PR expression as did E(2), in contrast to treatment with 10(-6) M MPA, which caused a downregulation of PR in epithelial cells, but not in fibroblasts. In addition, the vascular endothelial growth factor (VEGF) release into the cell culture medium was analyzed by a VEGF-ELISA. VEGF which plays an important role in angiogenesis, is regulated by steroid hormones as well as hypoxia. E(2) stimulates VEGF release into the medium in both cell types. MPA reduces VEGF release significantly in the fibroblast cell culture, but increases it in the epithelial cell culture. ZK137316, in the presence or absence of E(2), reduces VEGF release in fibroblast cell culture. J867 increases the VEGF production in fibroblasts only in the presence of E(2). Both compounds show no significant effects, compared to E(2), in epithelial cell culture. The different results for the epithelial cells and fibroblasts indicate that the pharmacological effects of PR modulators (PRMs) and progesterone antagonists (PAs) may be cell specific and depend on the presence or absence of partial progestagenic agonistic activities. This observation opens up new perspectives for various clinical applications.

Cell Culture Techniques↗

PubMed1992

A method for characterization of endogenous ligands to orphan receptors belonging to the steroid hormone receptor superfamily--isolation of progesterone from pregnancy plasma using progesterone receptor ligand-binding domain.

An analytical method is described whereby progesterone is isolated from pregnancy plasma on the basis of the high affinity and specificity of the progesterone receptor for its ligand. Partially purified progesterone receptor ligand-binding domain, expressed as a protein A fusion protein in Escherichia coli, is incubated with a neutral steroid fraction obtained by extraction and ion-exchange chromatography of human late-pregnancy plasma. The incubated sample is passed through two Lipidex 1000 (lipophilic gel) beds. The first, at 4 degrees C, separates the specific ligand-fusion protein complex from nonspecifically bound and unbound compounds, and the second, at 40 degrees C, separates the specific ligand from the protein. Elution of the second bed with methanol yields a fraction containing specific ligand that can be characterized by gas chromatography-mass spectrometry. This methodology may be valuable for identification of endogenous ligands to orphan receptors of the steroid hormone receptor superfamily.

Chromatography, Ion Exchange↗

PubMed1982

Estrogen and progesterone receptors in mammary tumors induced in rats by simultaneous administration of 17 beta-estradiol and progesterone.

Mammary tumors were promoted in male rats of the Wistar WAG strain by continuous and simultaneous administration of 17 beta-estradiol and progesterone. Tumor induction and growth were dependent on estradiol and on progesterone. Their histological features were comparable with those of human breast cancers. Hormone receptors were present in tumor cells. Estradiol receptor was found in 95% of them, at a higher level in nuclei than in cytosol. Progesterone receptor was present in 75% of tumors. In all cases, the level of androgen receptor was low.

Animals↗

PubMed1992

Progesterone regulation of progesterone receptor in mesometrial and antimesometrial deciduoma in pseudopregnant hamster.

Experiments were performed to examine the trophic effects of progesterone (P) on the progesterone receptor (PR) and the maintenance of the deciduoma. Deciduomal reactions in response to artificial stimuli were induced in hamsters' uteri on the 4th (D4) day of pseudopregnancy (PSP). On and after the 8th day, PSP hamsters received P supplement (2mg; s.c.) daily. Histological observation revealed that the life span of the deciduoma was partially prolonged. The maintenance and regression of the deciduoma was heterogeneous. P was able to maintain the morphology of the cells at the mesometrial site (MS) on D12, whereas cells at the antimesometrial site (AMS) regressed. The cytosol progesterone receptor (cPR) concentration in cells of the MS was higher than that of the AMS on D10. The cPR in MS and AMS decreased drastically on D12. The nuclear PR (nPR) remained at a higher concentration in both tissues on D10 followed by a precipitous decrease. The deciduomal nPR in the AMS decreased at a faster rate. By day 12, the nPR in the MS was much higher than that in the AMS. These data show that P acts as a trophic hormone of the deciduoma. The maintenance of deciduoma is closely related to the presence of PR. Other mechanisms may exist for the heterogeneous responses observed at the MS and AMS.

Animals↗

PubMed1990

Chick oviduct differentiation. The effect of estrogen and progesterone on the expression of progesterone receptor.

Progesterone receptor (PR) is a marker of estrogen action. Its cellular appearance during estrogen (20 mg/kg i.m.)-induced differentiation of the immature chick oviduct was therefore studied by immunohistochemistry. PR was located in the epithelial, mesothelial, submucosal stromal and smooth muscle cells. Progesterone (20 mg/kg i.m.) caused an obvious decrease in PR immunoreactivity without inducing synthesis of progesterone-dependent avidin. Thus mere receptor occupation by ligand is not sufficient for this induction. This paper reports that the expression of PR in the mucosal stromal cell differs from that in other cell types. In the mucosal stromal cell PR was inducible, i.e., not shown without the action of estrogen. The formation of tubular glands did not commence before mucosal stromal cells expressed PR. It would seem that the mucosal stromal cells have a crucial role in mediating epithelial differentiation. The onset of differentiation was preceded by vascularization and invasion of mononuclear cells in the submucosa. It was conspicuous that the smooth muscle cells of arteries also contained PR.

Animals↗

PubMed1993

Non-consensus progesterone response elements mediate the progesterone-regulated endometrial expression of the uteroferrin gene.

A 2.0 kilobase-pair (kb) fragment encompassing the promoter and 5' flanking region of the uteroferrin (UF) gene was previously demonstrated to confer progesterone (P) responsiveness to chimeric UF gene promoter-reporter gene constructs when transfected in endometrial cells. In the present study, transient transfection experiments with the chloramphenicol acetyltransferase reporter gene linked to the sequentially deleted UF gene 5' flanking region and to genomic fragments within this region subcloned into the heterologous SV40 promoter were used to define the progesterone-responsive elements (PRE). The identified PREs are located distal to the promoter in the region between -1754 to -1601 bp and -893 to -678 bp of the UF gene and exhibit only limited similarities to the half-sites of the consensus palindromic PRE. The non-consensus PREs bind the progesterone receptor (PR) and independently exhibit P-dependent enhancer activities within the context of homologous and heterologous promoters in endometrial and placental cell lines. The unique features of these functional PREs suggest that formation of the P-PR complex with its cognate sequences upstream of the UF gene may be less dependent on the sequence per se but may require the binding of nuclear factors proximal to the PRE to stabilize PRE-PRE interactions.

Acid Phosphatase↗