Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Promegestone”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed1988

Antiglucocorticoid RU 38486 attenuates retention of a behaviour and disinhibits the hypothalamic-pituitary adrenal axis at different brain sites.

Adrenalectomized rats displayed a deficiency in retention of an immobility response acquired during an initial 15-min forced swimming procedure (Porsolt swimming test) and measured 24 h later in a 5-min retest session. The deficit could be restored dose dependently with the glucocorticoid dexamethasone (microgram range) administered 15 min after the initial test. The antiglucocorticoid RU 38486 administered subcutaneously (1 and 10 mg/kg) inhibited the dexamethasone effect and caused a parallel shift in the dose-response curve of dexamethasone. Intracerebroventricular administration of RU 38486 to intact rats immediately before the initial test attenuated retention of acquired immobility over a 100,000-fold lower dose range (ng) and increased the plasma corticosterone level. Local administration of 1 ng RU 38486 in the dentate gyrus of the hippocampus also diminished the percentage immobility, but did not influence the adrenocortical response. Injections of RU 38486 in parafascicular and paraventricular nucleus were ineffective on behaviour. In the latter nucleus the antiglucocorticoid disinhibited the activity of the hypothalamus-pituitary-adrenal axis. Intracerebroventricular pretreatment with promegestone did not interfere with RU 38486 action, ruling out involvement of its antiprogestin properties. Intracerebroventricular or subcutaneous treatment of intact rats with the antimineralocorticoid RU 28318 was not effective. Finally, adrenalectomized rats replaced with corticosterone delivered via subcutaneously implanted 100-mg corticosterone pellets showed normal behavioural performance, while a 25-mg implant did not. The present study with local infusions of RU 38486 indicates that glucocorticoid feedback via type 2 receptors exerts a long-term influence on behaviour in the hippocampus and controls the activity of the hypothalamus-pituitary-adrenal axis in the paraventricular nucleus.

Adrenalectomy↗
PubMed1997

Immunochemical demonstration of the mineralocorticoid receptor in ocular tissues.

We studied the presence of the mineralocorticoid receptor (MCR) in the eye with the aid of a number of immunochemical techniques. Immunoblotting with a polyclonal antibody, directed against the rat renal MCR, revealed a single band of about 102 kD in extracts prepared from whole bovine or rat retina similar to that observed in cytosol from the kidney and myocardium from these species. Isolated cells of the bovine retinal pigment epithelium (RPE) similarly exhibited a 98- to 102-kD band in Western blots developed with the aid of anti-MCR antiserum. The 98- to 102-kD band was also obtained following autoradiography of RPE cytosol irradiated in the presence of 3H-R 5020. This fluorographic pattern was abolished when RU 26752, an antagonist specific to the MCR, was allowed to compete with radiolabelled promegestone. The MCR-3H-RU 26752 complex in RPE cytosol underwent heat activation, as judged by binding to DNA cellusose, and could also be precipitated by anti-MCR IgG. In primary cultures, the proliferation of the RPE cells was inhibited by the two MCR-specific antagonists RU 26752 and ZK 91587. The loss of the MCR-specific immunofluorescence in RPE cells after only 3 passages in culture was associated with refractoriness to the inhibitory effect of both of these spironolactones. Immunohistochemistry, using MCR-specific antiserum, revealed strong fluorescence in specific areas of the rat eye. In the retina, immunopositivity was observed in Müller cells, external and internal limiting membranes, the vitreous base lining and in the pigment epithelium. Epithelial cells of the ciliary body, iris and cornea also exhibited strong MCR-specific immunofluorescence. Thus, both the epithelial and the nonepithelial compartments of the ocular tissues form interesting new targets to delineate the mechanism of action of mineralotropic hormones.

Animals↗
PubMed1980

Progesterone and estrogen receptors in GH3 cells.

GH3 cells are shown to contain cytosolic progesterone receptor in a mean concentration of 270 fmol/mg protein with a dissociation constant (K(D)) for promegestone of 3 times 10(-9) M (4 degrees C). Estrogen receptor (K(D) = 1.8 times 10(-10) M) is demonstrated in cytosol (121 fmol/mg protein) as well as in 0.4 M KCl extracts (89 fmol/mg protein) of crude nuclear fractions. No progesterone receptor was detectable in the nuclear fraction. Both receptors are characterized by isoelectric focussing and by competition experiments. Addition of 10(-8) M estradiol to the growth medium increases progesterone receptor levels up to five, suggesting that the progesterone receptor is under estrogenic control.

Animals↗
PubMed2006

Dimethandrolone undecanoate: a new potent orally active androgen with progestational activity.

Dimethandrolone (DMA), the 17beta-undecanoic acid ester of dimethandrolone (DMAU; 7alpha,11beta-dimethyl-19-nortestosterone) is a potent androgen currently in development for therapeutic uses in men. Cleavage of the 17beta-ester bond liberates the biologically active DMA. In this study we investigated the activity of DMAU and DMA both in vivo and in vitro. DMAU was active orally in castrate rat bioassays, and when administered sc, a single dose produced prolonged androgenic activity and suppression of LH with sustained circulating levels of DMA. DMA, other 19-norandrogens, and C-19 androgens bound to recombinant rat androgen receptor with high affinity and were equipotent in stimulating luciferase activity (EC50, 10(-10) -10(-9) M) in CV-1 cells cotransfected with a human androgen receptor expression vector and a luciferase reporter plasmid with three hormone response elements. Because various 19-norandrogens are also known to bind to progestin receptors (PR) and to possess progestational activity in vivo, we evaluated the binding affinity of DMA for rabbit PR and recombinant human PR-A and PR-B and its ability to induce PR-mediated transcription and endogenous alkaline phosphatase activity in T47DCO human breast cancer cells. DMA and related 19-norandrogens bound with high affinity to both rabbit and human PR, whereas the less active 11alpha-methyl stereoisomer of DMA and C-19 androgens showed low or negligible binding to PR. In T47DCO cells, 10(-8) M DMA and other 19-norandrogens stimulated transcription of a progestin/glucocorticoid/androgen response element-thymidine kinase-luciferase reporter plasmid to the same extent as R5020, the potent progestin promegestone (EC50, approximately 10(-9) M), but C-19 androgens had no effect. Antiprogestins were potent inhibitors of transactivation and alkaline phosphatase activity induced by DMA and other 19-norandrogens in T47DCO cells, whereas antiandrogens were weak inhibitors. DMA and DMAU also exhibited dose-dependent progestational activity in the estrogen-primed immature female rabbit, as assessed by induction of endometrial gland arborization. The dual androgenic and progestational activities of DMA make it a potential candidate for a single-agent male contraceptive as well as for androgen therapy in men, pending a successful outcome of pharmacokinetic and toxicity studies currently in progress.

Administration, Oral↗
PubMed1984

1,25-dihydroxyvitamin D3 receptors in the seminiferous tubules of the rat testis increase at puberty.

Whether 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] receptor levels correlate with the rapid in vivo growth rate of the testes in the prepubertal rat was examined. Low salt chromatin-localized 1,25-(OH)2D3 receptors were compared in the testes and intestinal mucosa (control) of prepubertal, peripubertal, and mature rats (37, 49, and 90 days old, respectively). The number of 1,25-(OH)2D3 receptors per g wet wt was significantly (P less than 0.02) reduced in the testes of the prepubertal rats compared to those in the peripubertal and mature groups. Conversely, no changes were observed in the 1,25-(OH)2D3 receptor levels in the control tissue intestinal mucosa among these age groups. Further experiments confirmed the identity of the testicular 1,25-(OH)2D3 receptors. The specific [3H]1,25-(OH)2D3-binding component was predominantly localized in the nuclei/chromatin fraction in hypotonic buffers. Scatchard analysis of [3H]1,25-(OH)2D3 binding to the testicular chromatin of adult rats yielded a single specific binding component with a Kd of 0.33 +/- 0.06 nM and a Nmax of 102.3 +/- 6.4 fmol/g tissue (n = 6), which was inhibited by excess 1,25-(OH)2D3, but only minimally by 50 nM 25-hydroxyvitamin D3. Sucrose gradient analysis required hydroxylapatite treatment of fractions after centrifugation to remove free 3H-labeled steroid. With this modification, a discrete 3.6S peak of [3H]1,25-(OH)2D3 was unmasked, which was eliminated by excess 1,25-(OH)2D3, but not by 50 nM 25-hydroxyvitamin D3, or 1 microM cortisol, or the progesterone analog promegestone. In spite of its seemingly ubiquitous distribution, the 1,25-(OH)2D3 receptor does exhibit tissue specificity, since it appears to be absent in the prostate and, at best, greatly reduced in the epididymis. The cellular localization of the testicular 1,25-(OH)2D3 receptors was examined by mechanically separating interstitial cells (93.7% of the total [125I]hCG binding) from the tubules. Under these conditions, 91.3% of the specific [3H]1,25-(OH)2D3 binding occurred in the tubular chromatin preparation. Thus, these data provide evidence for the presence of a specific 1,25-(OH)2D3 receptor in the seminiferous tubules of the rat testis. Moreover, the temporal correlation of increased 1,25-(OH)2D3 receptor levels with testicular maturation suggests a better correlation to testicular function and spermatogenesis than to growth of the organ in vivo.

Aging↗
PubMed1992

Androgen and progesterone receptors in shark (Squalus) testis: characteristics and stage-related distribution.

Although testosterone (T) is essential for the normal completion of spermatogenesis, the exact T-sensitive control points are still unknown. Using staged tissues (premeiotic, PrM; meiotic, M; and postmeiotic, PoM) from zonal testes of the spiny dogfish Squalus acanthias, and standard [3H] steroid binding analysis, we characterized a T-binding component with physiochemical characteristics resembling classical androgen receptors (AR). [3H]T binding was of high affinity (dissociation constant = 4.4 x 10(-9) M), limited capacity (maximum binding, 94 fmol/g tissue) and relatively stable (t1/2 = 4 h at 4 C). The T-binding component was present in both cytosolic and nuclear extracts, adhered to DNA-cellulose, and displayed predicted sedimentation properties of an activated receptor in vivo or in vitro (5.06S). T, 5 alpha-dihydrotestosterone (DHT), and mibolerone (Mib), but not methyltrienelone (R1881), competed well for [3H]T binding; however, progesterone (P) was equivalent to T in its ability to displace tracer. Subsequent analysis of [3H] P binding revealed a P-binding component that was present in nuclear and cytosolic extracts, adhered to DNA, but differed from AR in its inability to bind Mib. Competition studies in which excess radioinert Mib was used to block AR revealed ligand specificity characteristics of progesterone receptors (PR): promegestone (R5020) greater than P greater than deoxycorticosterone, but T, DHT, dexamethasone, and corticosterone were ineffective competitors. Also, a nonlinear Scatchard plot was obtained, suggesting two P-binding activities, which differed in their binding affinities (dissociation constant = 0.88 vs. 5.9 x 10(-9) M) and capacities (66 vs. 210 fmol/g tissue). Conversely, using [3H]Mib to avoid interference from PR, we confirmed that T, DHT, and P were equivalent in their ability to displace ligand from AR. Comparison of tissues by stage of spermatogenesis revealed different distribution patterns for AR (PrM greater than M much greater than PoM) vs. PR (PoM much greater than M = PrM). These data provide definitive evidence for separate testicular T- and P-binding mechanisms and indicate the presence of temporally distinct sets of steroid-regulated genes.

Analysis of Variance↗
PubMed1982

Simultaneous measurement of progesterone and androgen receptors in human prostate: a microassay.

The characteristics of binding of radiolabeled progesterone, promegestone [17 alpha,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione (R5020)], medroxyprogesterone acetate (4-pregnen-6 alpha-methyl-17 alpha-ol-3,20-dione acetate), and methyltrienolone [17 beta-hydroxy-17 alpha-methyl-4,9,11-estratriene-3-one (MT)] to the progesterone receptor in human prostatic cytosol have been compared. MT binds to both androgen and progesterone receptors with high affinity (Kd = 0.9 and 0.6 nM, respectively). The binding of MT to the progesterone receptor can be blocked by adding an excess of unlabeled triamcinolone acetonide [9 alpha-fluoro-11 beta, 16 alpha, 17 alpha,21-tetrahydroxy-1,4-pregnadiene-3,20-dione-16,17-acetonide (TAC)]. The difference between the binding of [3H]MT in the absence and presence of TAC (i.e. [MT - (MT + TAC)] represents specific binding of MT to the progesterone receptor. Ligand specificity studies demonstrated that this binding was typical of a progesterone receptor. Furthermore, progesterone receptor levels measured in this way were comparable to those obtained using progesterone, R5020, or medroxyprogesterone acetate as labeled ligands. Progesterone receptor quantitation from the difference MT - (MT + TAC) is of particular advantage when simultaneous quantitation of progesterone and androgen receptors is desired in small tissue specimens since only three sets of incubations are required: [3H]MT, [3H]MT plus unlabeled TAC, and [3H]MT plus unlabeled MT (to measure nonspecific binding). Conditions are described for the application of this methodology to a microassay. A marked underestimate of progesterone receptor content was observed when incubation was terminated with hydroxylapatite compared to that measured when dextran-coated charcoal was used. The presence of comparable amounts of progesterone and androgen receptors in human prostatic cytosol deserves further investigation.

Binding, Competitive↗
PubMed1983

Characterization of the cytosol androgen receptor of the human prostate.

Direct measurement of the binding of endogenous androgens to the androgen receptor of human tissues has not been possible because of contamination of tissue with traces of plasma proteins, such as testosterone-binding globulin (TeBG), that contain more androgen-binding capacity than does the receptor itself. Molybdate is known to stabilize the 8-9S forms of other steroid hormone receptors. We took advantage of this phenomenon to characterize the androgen receptor of hyperplastic prostates removed at surgery, using sucrose density gradient centrifugation in a vertical rotor. In 10 mM sodium molybdate, the androgen receptor sediments as a distinct 9.2 +/- 0.5S moiety, easily separable from TeBG. Unlike TeBG, the 9S receptor is not removed by absorption with Concanavalin A. [3H]Dihydrotestosterone (3H-labeled 17 beta-hydroxy-5-alpha-androstan-3-one) binding to the 9S receptor is not removed by absorption with Concanavalin A. [3H]Dihydrotestosterone (3H-labeled 17 beta-hydroxy-5 alpha-androstan-3-one) binding to the 9S receptor is not competed for by excess triamcinolone acetonide (9 alpha-fluoro-11 beta, 16 alpha, 17 alpha, 21-tetrahydroxypregna-1,4-diene-3,20-dione cyclic 16,17-acetonide) or promegestone (17,21-dimethyl-19-non-pregna-4,9-diene-3,-20-dione), which are known to bind to the progestin receptor. In contrast, [3H]methyltrienolone (3H-labeled 17 beta-hydroxy-17 alpha-methyl-estra-4,9,11-trien-3-one) binds to both androgen and progestin receptors, and consequently, the binding of this ligand to the androgen receptor was assessed in the presence of a 500-fold excess of triamcinolone acetonide. The amounts of 9S binding (7.8 and 5.8 fmol/mg protein) are similar for dihydrotestosterone and methyltrienolone. The amount of 9S binding of testosterone to the receptor was also similar to that of dihydrotestosterone, but the affinity of testosterone for the 9S receptor was only a fifth or less of that for dihydrotestosterone. The observation that testosterone binds less avidly than dihydrotestosterone to the receptor may explain the role of dihydrotestosterone formation in androgen physiology.

Centrifugation, Density Gradient↗
PubMed1991

Increased nuclear type II estradiol receptor concentrations in rat spleen during the course of pregnancy.

Estradiol receptors are classified into type I and type II receptors by their affinity and capacity for estradiol binding. The type II receptors are thought to be significant in the suppression of immune response, such as in the pregnancy-associated immunosuppression. The present study was undertaken to show the presence of type II receptors in rat spleen and to examine the change of receptor distribution after estradiol administration and during pregnancy. Scatchard analysis revealed that the type II receptors were present in rat spleen, and dissociation constants were estimated to be 3.23 x 10(-9) M for cytosol and 4.29 x 10(-9) M for nuclei. The receptors possessed specificity for estradiol and diethylstilbestrol, but not for promegestone, methyltrienolone and dexamethasone. Administration of estradiol to rats resulted in the increase of nuclear receptor concentrations with concomitant decrease of cytosolic concentrations. During pregnancy, the receptor concentrations were increased in the nuclear fraction, but were not significantly changed in the cytosolic fraction. The dissociation constants of the receptors in pregnant rat spleen (4.77 x 10(-9) M for cytosol and 7.20 x 10(-9) M for nuclei) were similar to those in the non-pregnant control, suggesting the quantitative change of the receptors during pregnancy.

Animals↗
PubMed1988

Progestin and estrogen receptors: characterization and localization in rat submandibular glands, with special reference to epidermal growth factor.

By using progestin (P) and estrogen (E), the localization and characterization of both steroid receptors were examined in the submandibular gland (SMG) of 6-week-old immature castrated rats, with special reference to localization of epidermal growth factor (EGF). In the castrated male and female rats, both 3H-estradiol-17 beta (3H-E2 beta) and 3H-promegestone (3H-R5020) bound to SMG cytosol with high affinity and low capacity. These values were similar to those reported for other tissues. However, E-treatment after castration inhibited the specific binding. In sucrose density gradient ultracentrifugation, it was found that P receptors in both castrated males and females had a sedimentation coefficient of 7S, whereas E receptors had sedimentation coefficients of 4S and 7S. A histochemical study of the SMG of castrated male and female rats showed that the E-peroxidase complex (EPC)- and P-peroxidase complex (PPC)-stained cells were predominantly located in the epithelium of the duct system including the excretory duct and the granular convoluted tubules. Few cells were located in the intercalated duct, and none were found in the acinus. EGF-immunoreactive cells were also located in the epithelium of the same tissue region as in PPC- and EPC-stained sections. Moreover, E-treatment after castration inhibited the intensity of staining and immunoreactivity. These results clearly suggest that rat SMG contains specific P and E receptors which are mainly located in the epithelial cells of the duct system in which EGF-containing cells are identified. We discussed the possibility that P and E might affect EGF immunoreactivity, which reflects EGF production, through their receptors in the epithelium of the duct system.

Animals↗
PubMed1986

Steroid binding to feather follicles in the chicken.

Steroid binding profiles in chicken feather follicles were studied in vitro. Progesterone and promegestone were bound specifically with high affinity (dissociation constant = 7.79 nmol/l in females and 2.0 nmol/l in males) and with low capacity to the high-speed supernatant fraction (cytosol) of homogenized feather follicles. The number of progestin-binding sites was significantly (P less than 0.01) higher in females than in males (1.35 +/- 0.07 (mean +/- S.D.) vs 0.605 +/- 0.15 pmol/mg protein). Significant cross-competition was observed between progestins and glucocorticoids for the binding sites. The heat-activated progestin-receptor complexes bound specifically to DNA-cellulose in vitro. The DNA-cellulose binding was 36.6% of the total specific binding. The presence of progestin-binding sites in the feather follicles implies a direct action of progesterone in this structure, which may be an important factor in the regulation of moulting. The lack of oestrogen binding to the cytosol prepared from the feather follicles suggests different regulation of progestin receptors in different target organs.

Animals↗
PubMed1986

Cytoplasmic progesterone receptors in uterine tissue of the snapping turtle (Chelydra serpentina).

A high affinity progesterone-binding component was detected in the cytosol of the uterus of the snapping turtle, Chelydra serpentina. Density gradient centrifugation indicated that binding of [3H]progesterone and [3H]promegestone (R5020) was to a fraction with a heavier sedimentation coefficient than bovine serum albumin (BSA) appearing as a broader peak in the 6-7 S region; it was not affected by excess cortisol. Another binding peak, lighter than BSA and appearing with [3H]R5020 and [3H]progesterone near the 4 S region, was affected by excess cortisol. Excess progesterone decreased both the heavier and lighter peaks. Analysis of steroid specificity revealed that, of the natural steroids, progesterone had the highest affinity for the uterine cytosol. This was followed by deoxycorticosterone, 5 alpha-pregnanedione, testosterone, oestradiol-17 beta, corticosterone, 5 alpha-dihydrotestosterone and cortisol. Non-linear regression analysis of saturation data indicated the presence of two classes of high affinity binding sites: progesterone-binding sites (R-sites) with equilibrium association constants (Ka) of 2.9 +/- 0.28 litres/nmol (mean +/- 95% confidence limit) for [3H]R5020 and 0.34 +/- 0.20 litres/nmol for [3H]progesterone, and corticosteroid-binding globulin-like sites (G-sites) with Ka of 4.5 +/- 1.6 litres/nmol for progesterone. The concentration of R-sites was between 0.66 +/- 0.10 and 2.6 +/- 0.55 pmol/mg protein while that of G-sites was between 0.73 +/- 0.05 and 5.0 +/- 0.27 pmol/mg protein. DEAE-cellulose filtration assay also confirmed the presence of R-sites and G-sites in the cytosol. R-sites were detectable without oestrogen priming during the preovulatory and vitellogenic phases (low progesterone, high oestrogen concentrations) when the ovarian follicles are mature (18-22 mm diameter).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Progesterone receptor in the human uterine cervix.

A progesterone receptor (PR) in human uterine cervical nuclei was demonstrated by a nuclear exchange assay using a synthetic progestin, promegestone (R5020) as a radio-labeled ligand. Total exchange of previously bound progesterone with R5020 was achieved by incubation at 0 degree C for 3 h. A 0.6 M KCl solution was used to extract the nuclear PR in uterine cervical tissue, and the dextran coated charcoal (DCC) method was used to separate the free [3H] R5020 from the bound form. Scatchard plots of nuclear PR binding showed two components with dissociation constants of Kd = 2.3 X 10(-10) and 4.6 X 10(-9) M. Three histological regions of the uterine cervix was studied as to their nuclear PR contents throughout the menstrual cycle. In the follicular phase, the connective tissue (CT) had the highest PR concentration (658.9 fmole/mg DNA), followed by the columnar epithelium (CE) (253.6 fmole/mg DNA), and the squamous epithelium (SE) (184.7 fmole/mg DNA). In the luteal phase, there was no significant difference among the three regions. Comparing these phases of cycle revealed that the CT had higher PR contents in the follicular phase than in the luteal phase, but no such difference was found in the CE or SE. These three regions had the same Kd value in both phases.

Adult↗
PubMed1998

Thyroid profile modifications during oral hormone replacement therapy in postmenopausal women.

There are few data available about changes in thyroid hormone profiles after hormone replacement therapy (HRT). We analyzed the effect of two different oral estrogens/progestins (E/P) associations on thyroid hormones and thyroxine-binding globulin (TBG) levels in 14 postmenopausal normal women distributed at random into two groups. Both groups received daily for a year 2 mg of estradiol valeriante per os. In Group A (n = 7), estrogen was associated with norethisterone acetate. In Group B, estrogen was associated with promegestone in a similar schedule to Group A. Blood samples were withdrawn to measure estradiol (E2), thyroxine (T4), triiodothyronine (T3), free T4 (fT4), thyroid-stimulating hormone (TSH) and TBG before and after 3, 6 and 12 months of treatment. Estradiol level increased significantly in both groups, being higher in Group A than in B. Under therapy, T4 and TBG levels were increased in both groups, but within the normal range. T4 mean level increased by 34% in Group A and 20% in Group B. TBG increment was slightly significant for Group A (p < 0.02); with only a trend in Group B (p = 0.08). T3, fT4 and TSH levels did not change significantly and remained within the normal range. Oral therapy with associated E/P produces moderate increases in T4 and TBG levels. Our results suggest that in postmenopausal women on oral HRT, fT4 and TSH levels are the most useful tools to evaluate the thyroid axis status.

Administration, Oral↗
PubMed1987

Estrogen receptor immunoreactivity in meningiomas. Comparison with the binding activity of estrogen, progesterone, and androgen receptors.

Estrogen receptor (ER) analysis was performed in 70 meningioma samples by means of two assays: an enzyme immunoassay that used monoclonal antibodies against human ER protein (estrophilin), and a sensitive radioligand binding assay that used iodine-125-labeled estradiol as the radioligand. Low levels of ER immunoreactivity were found in tumors from 51% of patients, whereas ER binding activity was demonstrated in 40% of the meningiomas examined. In eight (11%) of the tissue samples, multiple binding sites for estradiol were observed. The immunoreactive binding sites corresponded to those of the classic high-affinity ER. In ligand binding studies, however, measurement of classic ER was considerably influenced by a second low-affinity high-capacity estrogen binding component, even at low ligand concentrations. Binding activity of the progesterone receptor (PR) and androgen receptor (AR) was determined concurrently using 17 alpha-methyl-3H-promegestone (3H-R 5020) and 17 alpha-methyl-3H-trienolone (3H-R 1881), a synthetic gestagen and androgen, respectively. High concentrations of PR were detected in 53 (76%) of the tumors, whereas a moderate number of AR binding sites were demonstrated in 33 (47%) of the tumors. A positive correlation between ER immunoreactivity and AR binding activity is suggestive of estrogen regulation of AR via the ER system. The presence of gonadal steroid receptors in a large proportion of meningiomas and the tendency toward a dependence of receptor concentrations on the histological subtype of the meningioma could have implications for tumor therapy.

Female↗
PubMed1994

Changes in progesterone receptor binding of preoptic hypothalamus during an ovulatory cycle of the hen.

By the use of radioligand assays, cytosolic and nuclear fractions of hypothalamic tissue involving preoptic area (HPOA) of the hen was found to contain a specific [17 alpha-methyl-3H]promegestone ([3H]-R5020; a synthetic progesterone) binding component having properties of receptor for progesterone. The equilibrium dissociation constant (Kd) was different neither between cytosolic and nuclear fractions nor between the fractions of laying and nonlaying hens. The maximum binding capacity (Bmax) per milligram of tissue of both fractions was greater in laying hens than in nonlaying hens. During the ovulatory cycle of laying hens, the specific [3H]-R5020 binding in cytosolic fraction showed a decrease, with an increase in the nuclear fraction from 21 to 18 h and from 6 to 3 h before ovulation. Such a change was not observed in nonlaying hens during a 24-h day. The results suggest that progesterone receptors are present in the preoptic hypothalamus and may be related to the incidence of ovulation in the hen.

Animals↗
PubMed1999

Conditionally adherent growth of serum-independent CHO cells for automated drug screening and biopharmaceutical production.

SSF3 is a CHO cell line adapted for growth in protein-free medium. It grows in suspension unless serum-derived attachment factors such as vitronectin are added to the medium. Serum-independent cell lines, which adhere to the substrate after induction with dexamethasone or constitutively, were created by transfection with a human vitronectin gene under control of the mouse mammary tumor-virus promoter. Substrate attachment and SSF3VN-cell spreading could be prevented with an RGD peptide (arginine-glycine-aspartic acid) confirming that attachment is mediated by an intregrin receptor. Hormone-inducible attachment could be blocked by glucocorticoid antagonist promegestone. All steps in the isolation of stable transfected SSF3VN cell lines could be done in a chemically defined medium avoiding the risk of introduction of serum-derived infectious agents. SSF3VN cells could be grown in protein-free medium in solid-phase large-scale bioreactors. Application in microplates as used in high-throughput screening was demonstrated in an assay of Ca(2+) release from internal stores induced by agonist-binding to recombinant human metabotropic glutamate receptor hmGluR1b.

Animals↗
PubMed1992

Progesterone blocks cholesterol translocation from lysosomes.

Fluorescent microscopic examination of fibroblasts cultured with low density lipoprotein (LDL) and progesterone (10 micrograms/ml) for 24 h revealed extensive filipin-cholesterol staining of perinuclear lysosomes. Levels of unesterified cholesterol were 2-fold greater than in fibroblasts cultured with LDL alone. Progesterone strongly blocked cholesteryl ester synthesis. When cellular uptake of LDL was monitored in the presence of 58035, a specific inhibitor of acyl-CoA:cholesterol acyltransferase, excess unesterified cholesterol was not stored in lysosomes. Discontinuation of LDL uptake in conjunction with progesterone washout markedly reversed the filipin-cholesterol staining of lysosomes. Reversal of the lysosomal cholesterol lipidosis was associated with a rapid burst of cholesteryl ester synthesis and a normalization of the cellular levels of free and esterified cholesterol. In contrast to normal cells, progesterone removal from Niemann-Pick C fibroblasts did not reverse the lysosomal cholesterol accumulation of these mutant cultures. The metabolic precursor of progesterone, pregnenolone, also induced extensive accumulation of cholesterol in lysosomes. Other steroids induced less vacuolar cholesterol accumulation in the following decreasing order: corticosterone and testosterone, promegestone, RU 486. The relative inhibition of cellular cholesterol esterification by the steroids paralleled their respective abilities to sequester cholesterol in lysosomes rather than their inhibition of acyl-CoA:cholesterol acyltransferase activity in cell-free extracts. The progesterone-related inhibition and restoration of lysosomal cholesterol trafficking is a useful experimental means of studying intracellular cholesterol transport. A particularly important feature of its utility is the facile reversibility of the steroid-induced block. The lysosomal cholesterol lipidosis established with a hydrophobic amine, U18666A, was not as readily reversed.

Androstenes↗