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PubMed1988

Conformational restrictions of the sheep testicular receptor discriminates pituitary lutropin and placental gonadotropins.

A membrane preparation from the testis of maturing Dorset-Leicester-Suffolk sheep, capable of discriminating pituitary LH (lutropin) from placental gonadotropins human choriogonadotropin (hCG) and equine choriogonadotropin is described. Maximum binding of 125I-oLH (ovine lutropin) to the testicular receptors occurred at 4 degrees C in a rapid manner, attaining equilibrium in 12-16 h. Under such optimal conditions, only unlabeled ovine LH or the structurally identical bovine LH effectively competed for receptor occupation. Other highly purified pituitary LH preparations from rat and human pituitaries were weakly (4-10%) active in displacement assays. Purified hCG or equine choriogonadotropin, which were highly potent in rat testicular LH receptor assays, could not compete with 125I-oLH for binding to the sheep LH receptor at 4 degrees C. Thus, the sheep testicular LH receptor was highly specific in recognizing pituitary LH conformation. The presence of an ovine/bovine LH alpha- or beta-subunit in recombinants with hCG subunit counterparts was required to generate an effective conformation capable of receptor recognition. Chemically deglycosylated hCG, containing 75% less carbohydrate and which showed greater binding to other LH receptors, failed to recognize sheep LH receptor, suggesting that excess carbohydrate in hCG was not a factor in hindering binding of the native placental hormone. Scatchard analysis using 125I-hCG/125I-oLH revealed that there were separate sites with similar affinities but vastly different capacities. The hCG binding sites, which could also be effectively occupied by oLH, were less than 10% of oLH binding sites. Thus, the Dorset-Leicester-Suffolk sheep testicular receptor provides an important and unique in vitro test system to distinguish pituitary LH from placental LH-like hormones. We infer that temperature-dependent conformational restrictions of the sheep testicular LH receptor are involved in recognizing differences in these highly similar and structurally homologous hormones.

Animals↗
PubMed1976

Circulating maternal serum progesterone in high-risk pregnancies.

Serum progesterone was measured by competitive protein-binding assay in 331 cases of normal pregnancy ranging from 6 to 42 weeks. Serial estimations of serum progesterone were performed in nine cases of severe hypertensive disorder of pregnancy, eight cases of twin pregnancy, three cases of twin pregnancy complicated by severe hypertensive disorder of pregnancy, three cases of triplet pregnancy, three cases of previous bad obstetric history, one case of anencephaly, and seven cases of intrauterine fetal death. Serum progesterone remained within normal range in severe hypertensive disorder of pregnancy and the levels were indistinguishable in cases of fetal growth retardation from those without growth retardation. In twin and triplet pregnancies, serum progesterone was within normal range or elevated and was usually higher than normal in twin pregnancies after weeks 33 to 34. Serum progesterone levels were normal in anencephalic pregnancy and in most cases of intrauterine fetal death. The findings are discussed with reference to placental hormonal activity. It is concluded that serum progesterone is a poor index of placental function.

Adult↗
PubMed2002

Predictive value of hormone measurements in maternal and fetal complications of pregnancy.

Intrauterine tissues (placenta, amnion, chorion, decidua) express hormones and cytokines that play a decisive role in maternal-fetal physiological interactions. The excessive or deficient release of some placental hormones in association with gestational diseases may reflect an abnormal differentiation of the placenta, an impaired fetal metabolism, or an adaptive response of the feto-placental unit to adverse conditions. This review is focused on the applicability of hormone measurements in the risk assessment, early diagnosis, and management of pregnancies complicated by Down's syndrome, fetal growth restriction, preeclampsia, preterm delivery, and diabetes mellitus. Combined hormonal tests or the combination of hormones and ultrasound may achieve reasonable sensitivity, but research continues to simplify the screening programs without sacrificing their accuracy. Only in a few instances is there sufficient evidence to firmly recommend the routine use of hormone tests to predict maternal and fetal complications, but the judicious use of selected tests may enhance the sensitivity of the risk assessment based solely on clinical and ultrasound examination.

Animals↗
PubMed2002

Hyperemesis gravidarum and subsequent breast cancer risk.

Both parity and a young age at first pregnancy are associated with a reduction in breast cancer risk. The hormones involved in this process are not fully investigated. Human chorionic gonadotropin is a placental hormone, which in rats and in human breast cells in vitro has been shown to prevent against breast cancer. Hyperemesis, a severe nausea combined with vomiting during pregnancy, is associated with increased levels of human chorionic gonadotropin. We investigated the possible relationship between hyperemesis and subsequent breast cancer risk in a case-control study based on registry data. Among 13 079 breast cancer cases and 34 348 individually matched controls we found 148 cases and 405 controls who had been hospitalised for hyperemesis. Hyperemesis was not associated with breast cancer risk (adjusted odds ratio 1.05, 95% confidence interval 0.86-1.27), and similar risks were observed regardless of age at diagnosis, number of hospitalisations for hyperemesis or time of follow-up. Our results do not support the hypothesis that human chorionic gonadotropin is responsible for the protective effect of pregnancies upon breast cancer risk.

Age Factors↗
PubMed1989

Expression of biologically active human follitropin in Chinese hamster ovary cells.

To study the structure-function relationships of follitropin (FSH), we expressed the hormone in a heterologous cell system. A genomic clone bearing a 3.7-kilobase FSH beta insert containing the entire coding sequence was transfected alone or together with the alpha subunit gene into Chinese hamster ovary cells and stable lines expressing either FSH beta or FSH dimer were selected. Pulse-chase experiments revealed that, when transfected alone FSH beta was very slowly secreted similar to lutropin beta and thyrotropin beta but unlike choriogonadotropin beta which is efficiently secreted. However, cotransfection of the FSH beta and alpha subunit genes resulted in "rescue" of the beta subunit and rapid secretion of dimer. These data support the hypothesis that the glycoprotein hormones of pituitary origin have determinants for secretion that differ from those on the placental hormone, choriogonadotropin. Recombinant FSH stimulated steroidogenesis comparable to purified human FSH isolated from pituitaries in an in vitro rat granulosa cell assay and appears more homogeneous by chromatofocusing. Human FSH produced by this cell line provides a source of bioactive FSH for experimental and clinical use.

Amino Acid Sequence↗
PubMed1984

Pre-parturitional changes in serum prolactin, placental lactogen, growth hormone, progesterone, and corticosterone in the C3H/HeN mouse.

Pre-parturitional changes in serum prolactin, placental lactogen, growth hormone, progesterone, and corticosterone in the C3H/HeN mouse are described. Serum prolactin concentrations display an apparent biphasic pre-parturitional increase. Both serum placental lactogen and growth hormone concentrations are elevated during the second half of pregnancy. Serum placental lactogen concentrations remain elevated until parturition, whereas serum growth hormone concentrations decline on the last two days of pregnancy. Serum progesterone and corticosterone concentrations are elevated during the latter half of pregnancy and decline on the day preceding parturition.

Animals↗
PubMed1980

Placental luteinizing hormone-releasing factor and its synthesis.

The synthesis of a placental luteinizing hormone-releasing factor (pLRF), which is immunologically, physiochemically, and biologically indistinguishable from synthetic LRF, was demonstrated. The incorporation of 3H-labeled leucine by human placental tissue in vitro into pLRF was determined by purification on carboxymethyl-cellulose and specific immunoprecipitation of the 3H-labeled pLRF. The specific activity of the pLRF released into the medium increased 100-fold from day 1 to day 2 of culture and attained a concentration of 2.84 microcuries per microgram. These data indicate that the pLRF that was released initially was endogenous, whereas that released subsequently reflected synthesis.

Culture Techniques↗
PubMed2005

The vitamin D receptor is not required for fetal mineral homeostasis or for the regulation of placental calcium transfer in mice.

We utilized a vitamin D receptor (VDR) gene knockout model to study the effects of maternal and fetal absence of VDR on maternal fertility, fetal-placental calcium transfer, and fetal mineral homoeostasis. Vdr null mice were profoundly hypocalcemic, conceived infrequently, and had significantly fewer viable fetuses in utero that were also of lower body weight. Supplementation of a calcium-enriched diet increased the rate of conception in Vdr nulls but did not normalize the number or weight of viable fetuses. Among offspring of heterozygous (Vdr(+/-)) mothers (wild type, Vdr(+/-), and Vdr null fetuses), there was no alteration in serum Ca, P, or Mg, parathyroid hormone, placental (45)Ca transfer, Ca and Mg content of the fetal skeleton, and morphology and gene expression in the fetal growth plates. Vdr null fetuses did have threefold increased 1,25-dihydroxyvitamin D levels accompanied by increased 1alpha-hydroxylase mRNA in kidney but not placenta; a small increase was also noted in placental expression of parathyroid hormone-related protein (PTHrP). Among offspring of Vdr null mothers, Vdr(+/-) and Vdr null fetuses had normal ionized calcium levels and a skeletal ash weight that was appropriate to the lower body weight. Thus our findings indicate that VDR is not required by fetal mice to regulate placental calcium transfer, circulating mineral levels, and skeletal mineralization. Absence of maternal VDR has global effects on fetal growth that were partly dependent on maternal calcium intake, but absence of maternal VDR did not specifically affect fetal mineral homeostasis.

Animals↗
PubMed1995

Expression of pit-1 messenger ribonucleic acid and protein in the human placenta.

It is well established that the human placenta produces a wide range of hormones similar to those secreted by the pituitary and hypothalamus. However, the physiological role and regulation of placental hormone synthesis and release are still largely unknown. GH (GH-N) is expressed in the pituitary, where it requires the tissue-specific transcription factor Pit-1. Chorionic somatomammotropin A (CS-A) and CS-B as well as the placental GH variant (GH-V), which also belong to the GH gene family and are located in the same chromosomal cluster, are expressed in the placental syncytiotrophoblast. The presence of Pit-1-binding sites in the CS-A and GH-V promoter regions predicts that Pit-1 may be expressed in the placenta. However, this has not yet been demonstrated. To examine possible similarities in the regulation of these genes in the pituitary and placenta, we studied the expression of pit-1 messenger ribonucleic acid (mRNA) in the human placenta, transformed human placental cells, and the JEG-3 choriocarcinoma cell line. Polymerase chain reaction (PCR) products of the expected size were amplified from first and third trimester placentas, transformed placental cells, and JEG-3 complementary DNA by reverse transcription-PCR. The pit-1-specific sequence was confirmed by restriction endonuclease digestion, Southern hybridization, and DNA sequencing. Human pituitary tissue was used as a positive control; no PCR product was obtained from hippocampus (negative control). In situ hybridization of placental tissue sections revealed the presence of pit-1 mRNA in first and third trimester syncytiotrophoblast. Pit-1 protein was localized by immunohistochemistry with the same tissue distribution and a nuclear localization pattern. These data demonstrate expression of pit-1 mRNA and Pit-1 protein in the human placenta, thus questioning its role as a pituitary-specific regulator of GH-N gene transcription. The expression of Pit-1 in the placenta, together with its previously demonstrated capability to bind to and activate the CS-A and the GH-V promoters, suggests that it may play a role in the regulation of hormones belonging to the GH gene family in both pituitary and placenta.

Base Sequence↗
PubMed1994

Pituitary-gonadal interactions in perinatal rats: relationships of plasma luteinizing hormone and testosterone concentrations, and pituitary levels of LH subunit mRNAs.

The functional state of the pituitary-gonadal axis was studied in rats on days 18.5-21.5 of fetal life (f) and on day 4 postpartum by measurements of plasma levels of luteinizing hormone (LH) and testosterone (T). LH was measured using an ultrasensitive immunofluorometric assay. In addition, male fetuses were castrated and exposed to the antiandrogen flutamide (FL; 100 mg/kg BW) or the Leydig cell-specific cytotoxic agent ethylene dimethane sulphonate (EDS, 50 mg/kg BW on 2 days) by injections of the drugs to the mothers. Besides LH and T, pituitary levels of LH subunit mRNAs were measured in these animals. The results allowed the following conclusions: (1) the plasma LH levels in both sexes are low (< 0.05 micrograms/l, NIH rLH RP-2) on days f18.5 and f19.5; (2) a 4- to 5-fold increase in plasma LH occurs between days f19.5 and f20.5, and a 3- to 4-fold sex difference appears (females > males); (3) the activation of fetal testicular T production before day f19.5 takes place in the face of very low plasma LH (< 0.02 micrograms/l), suggesting that some factor(s) other than LH may stimulate the testis at this age; (4) the reciprocal changes of plasma LH and T, and the experiments with castration, EDS and FL demonstrate that testicular feedback regulation of LH secretion is functional from day f19.5 onwards; (5) the parallel changes of T in male and female fetal plasma suggest that T in female fetuses comes from male littermates, and (6) the fetal pituitary-testicular axis is less sensitive to hormonal manipulations than that of the postnatal animal, possibly due to interference of maternal and placental hormones with the pituitary-testicular interactions.

Animals↗
PubMed1990

Identification of placental human growth hormone as the growth hormone-V gene expression product.

A GH variant of placental origin, placental GH, has recently been shown to replace pituitary GH in maternal serum during pregnancy. Besides, the GH variant (GH-V) gene has been demonstrated to be expressed in the placenta. The similarities between their known properties strongly suggest that the placental GH and the GH-V protein are the same molecular species. Here we provide final evidence that this is indeed the case by sequence analysis of both the 22K and 25K forms. Furthermore, the 25K form is shown to be glycosylated, while the 22K form is not. Both size variants of placental GH are, thus, likely to reflect the partial glycosylation of a unique peptidic chain.

Amino Acid Sequence↗
PubMed1994

Placental lactogen binding sites in the pregnant rabbit choroid plexus.

Prolactin has direct effects on the CNS. The highest concentration of prolactin receptors resides within the choroid plexus where they probably function to transport prolactin from blood into CSF. Another member of the lactogen family of hormones, placental lactogen (PL), also affects CNS activity and may similarly employ the cerebroventricular system as an intermediary. In order to determine whether the choroid plexus was a PL target tissue, in vitro autoradiography was used to identify specific PL binding sites in the choroid plexus of pregnant New Zealand White rabbits. Frozen brain sections were incubated in a medium containing 125I human PL (hPL) alone (total binding) or with a 500-fold excess of unlabelled hPL (nonspecific binding). The specificity of the binding was assessed with unlabelled human growth hormone (hGH) and ovine luteinising hormone (oLH). An intense autoradiographic reaction occurred over the choroid plexus of tissue sections incubated with 125I hPL alone. Excess unlabelled hPL and hGH, which is lactogenic in the rabbit, caused a significant reduction (P < 0.001) in the binding of radiolabelled hPL to the choroid plexus. In contrast, unlabelled oLH had no effect on radiolabelled hPL binding to this tissue. The results support a role for the choroid plexus in the interactions between PL and the CNS.

Animals↗
PubMed1979

Maternal hormone profile in oxytocin induced labour.

Serial blood samples were collected from ten patients at between 40 and 42 weeks gestation, who were having labour induced by amniotomy and intravenous oxytocin. The plasma levels of human placental lactogen and pregnancy-specific beta 1 glycoprotein showed no more than their normal late pregnancy variability during labour; oestradiol-17 beta showed a small rise in early labour followed by a fall in the second stage of labour; unconjugated oestriol and 11-hydroxycorticosteroids showed a progressive rise throughout labour and progesterone a progressive fall. The ratio of progesterone to oestradiol-17 beta fell throughout labour. The significance of these changes in our understanding of the control of placental hormone secretion and of the hormone profile of spontaneous labour is discussed.

11-Hydroxycorticosteroids↗
PubMed1979

Human chorionic gonadotropin in the plasma of normal, nonpregnant subjects.

To determine whether ectopic secretion of a protein hormone can occur normally, we studied plasma from normal, nonpregnant subjects for the presence of a placental hormone, human chorionic gonadotropin. We extracted and purified this hormone from other plasma proteins. We identified the hormone in the final residue on the basis of its dose-response curves in a specific radioimmunoassay and calculated the plasma concentration after correction for losses. Because this assay is sensitive to concentrations as low as 2 pg per milliliter, human chorionic gonadotropin could be detected in the plasma of 12 of 16 blood donors; the median concentration was 19 pg per milliliter (range, less than 2 to 361). This immunologic human chorionic gonadotropin was further characterized from a pool of normal plasma by gel filtration on Sephadex G-100 and was found to be identical to the standard form of the hormone. The concentration in this pool from 13 normal men was 18 pg per milliliter. The source of this ectopic hormone production is unknown, but may be normal, rapidly proliferating nonmalignant cells.

Adult↗
PubMed1994

Human luteinizing hormone and chorionic gonadotropin are targeted to a regulated secretory pathway in GH3 cells.

LH is a dimeric glycoprotein hormone that is stored in the anterior pituitary and is released in response to GnRH, while the placental hormone, human CG (hCG), sharing the same alpha-subunit and a related beta-subunit, is secreted constitutively. In search of a determinant that allows sorting of LH into a regulated secretory pathway, the genes encoding the common alpha- and LH/CG beta-subunits were expressed in the GH3 rat pituitary tumor cell line, which contains a regulated secretory pathway. Steady state labeling and subsequent chase experiments showed that not only LH but also hCG can be sorted to a regulated secretory pathway; after an initial period of constitutive secretion, the mature forms of both hormones containing processed oligosaccharides were stored intracellularly, and their release was stimulated by either forskolin or KCl depolarization. In Chinese hamster ovary cells, which lack a regulated pathway and are devoid of storage granules, only hormones containing unprocessed N-linked oligosaccharides were found. In GH3 cells the LH beta-subunit was partially retained in an endoglycosidase H-sensitive form, presumably in the endoplasmic reticulum; the enzyme-resistant fraction was secreted through a regulated secretory pathway. A large fraction of the hCG beta-subunit was released constitutively, although some mature hCG beta-subunit accumulated in secretory granules and was released by forskolin. The common alpha-subunit was secreted constitutively with little intracellular accumulation of the mature forms. We conclude that the LH beta-subunit contains sufficient information to direct LH to a regulated pathway, and alpha:LH beta assembly is not a prerequisite for this targeting. The sorting of hCG to a regulated pathway in GH3 cells presumably reflects a structural similarity between LH and hCG. In addition, we have shown that GH3 cells can recognize the N-linked oligosaccharides on the gonadotropin subunits as substrates for sulfation.

Animals↗
PubMed2004

Maternal serum and yolk hormone concentrations in the placental viviparous bonnethead shark, Sphyrna tiburo.

Among vertebrates, maternal transfer of hormones to offspring has been studied extensively in mammals (placental transfer) and more recently in oviparous birds and reptiles (yolk transfer). The placental viviparous bonnethead shark, Sphyrna tiburo, allows the investigation of both yolk and placental hormone transfers in a single organism. In this species, yolk provides nutrition for the first half of embryonic development and placental transfer provides the second half. As sex determination is complete prior to development of placental connections, it was postulated that yolk hormones would have a prominent role in embryonic regulation. The goal of the current study was to determine serum and yolk hormone concentrations during five reproductive stages, from pre-ovulatory through pre-implantation (pre-placental) stages. Radioimmunoassay was used to determine 17beta-estradiol, progesterone, and testosterone concentrations in both serum and yolk. When yolk and serum concentrations were compared, the yolk had significantly higher concentrations of both estradiol and progesterone during post-ovulation and early pregnancy. Yolk concentrations of testosterone were significantly less than serum at pre-ovulation, but there were no differences after that stage. When yolk concentrations were compared between stages, significantly higher concentrations of estradiol were present in ovulatory, post-ovulatory, and pre-implantation stages, while progesterone was significantly higher in post-ovulatory, early pregnancy, and pre-implantation stages and testosterone was higher in pre-ovulation. Most of these results are consistent with the published findings in birds and reptiles. Further, in the bonnethead shark, they suggest that yolk transfer of hormones is adequate for sexual differentiation in embryonic development and that estradiol probably has a significant developmental role.

Animals↗
PubMed1991

Immunocytochemical study of cell type distribution in the pituitary of Barbus barbus (Teleostei, Cyprinidae).

Antisera to mammalian pituitary and placental hormones have been used to identify and localize the different cell types in the pituitary of the barbel (Barbus barbus, L.). The immunocytochemical labeling employed the immunoperoxidase technique or the immunogold silver staining procedure. Corticotrophic and prolactin cells, visualized using antisera to human adrenocorticotropic hormone and ovine prolactin (PRL), respectively, occur in the rostral pars distalis (RPD). Antisera against mammalian gonadotropins [ovine follicle-stimulating hormone (FSH); bovine luteinizing hormone] or porcine growth hormone selectively cross-react with two different cell populations occupying the major part of the proximal pars distalis (PPD). Thyrotropic cells, stained by an antiserum to whole human thyroid-stimulating hormone preabsorbed with porcine FSH, are scattered throughout the PPD and found amongst growth hormone and gonadotrophic cells. The majority of pars intermedia cells are stained with anti-melanophore stimulating hormone whereas the scattered PAS positive cells are revealed by both anti-ovine PRL and anti-bovine placental lactogen (or chorionic somatomammotropin). The latter antiserum also cross-reacts with the PRL cells of the RPD. Our results indicate that the distribution of the different cell types in Barbus barbus is similar to that described in other families of teleosts. This report is also the first demonstration of antigenic similarity between mammalian placental lactogen and fish prolactin.

Adrenocorticotropic Hormone↗