Stimulation of hCG and inhibition of hPL in isolated human trophoblast cells in vitro by glycodelin A.

The immunosuppressive protein glycodelin A (formerly named PP14) is produced by human decidua and secreted in the maternal circulation. Glycodelin A concentrations in serum have been used as indicators of endometrial function. The purpose of this study was to investigate the effect of glycodelin A on human chorionic gonadotropin (hCG) and human placental lactogen (hPL) release by freshly isolated cytotrophoblasts (in vitro). Cytotrophoblasts have been prepared from human term placenta by the three-step trypsin-DNase dispersion method of villous tissue followed by a percoll gradient centrifugation step. When placed in culture, the isolated mononuclear trophoblasts differentiated into syncytial counterparts within 12-72 h after plating. Trophoblasts were incubated with varying concentrations (60-300 microg/ml) of glycodelin A. Glycodelin A was isolated and purified by chromatographic methods from amnion fluid. Supernatants of the trophoblast cell cultures were assayed for hCG and hPL by immunological methods. The release of hCG is increased in glycodelin A-treated trophoblast cell cultures compared to untreated trophoblast cells. Glycodelin A inhibits the production of hPL in vitro. Differences in Glycodelin A stimulated cells and untreated controls are statistical significant. hCG and hPL are markers for the differentiation process of trophoblast cells to syncytial trophoblasts. The results imply that glycodelin A secreted by decidualised endometrium modulates endocrine function, as well as the differentiation of trophoblasts in culture.

Effects of dopamine and estrogen on the regulation of Pit-1 alpha, Pit-1 beta, and PL-II gene expression in the rat placenta.

Pituitary-specific transcription factor Pit-1 regulates growth hormone and prolactin gene expression in the pituitary. Recently, Pit-1 was shown to be locally synthesized in the rat placenta and is involved in the regulation of rat placental lactogen (PL) gene expression. Pit-1 has three different splicing variants. They are well known as being biologically active. In the present study, we found that Pit-1 beta is also synthesized in the rat placenta and we tried to examine the effects of dopamine and estrogen on the regulation of Pit-1 alpha, beta and PL-II genes expression using the reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot hybridization. A dopamine receptor agonist, bromocriptine, significantly decreased placental Pit-1 alpha, beta, and PL-II mRNA levels. To examine the effect of estrogen on the gene expression of Pit-1 beta, pregnant female rats were ovariectomized (OVX) and injected daily with 17 beta-estradiol. OVX markedly lowered the amount of Pit-1 beta mRNA. Estrogen injection recovered the OVX-induced inhibition of Pit-1 beta mRNA level. Finally, we investigated the site-specific transcription of Pit-1 alpha and beta mRNA in the labyrinth zone and junctional zone of the placental in 15 and 20 days of gestation. The main site of Pit-1 alpha and beta synthesis was shifted from the junctional zone to the labyrinth zone from 15 to 20 days of gestation. Together, these data presume that Pit-1 beta may play a more important role in the placenta than in the pituitary and that Pit-1 may be involved in the regulation of the PL and prolactin-like peptide by estrogen and dopamine in the rat placenta.

Fenoterol increases erythropoietin concentrations during tocolysis.

AIMS: The present study was carried out to assess the effect of the selective beta2-adrenoceptor agonists on erythropoietin (EPO) production. METHODS: Routine tocolysis with fenoterol (using the regular rate of 2 microg min[-1]) was used as a clinically easily accessible model. RESULTS: EPO concentrations had doubled 24 h after the start of tocolysis (P < 0.001). This increase lasted over the entire observation period of 48 h. Potassium concentrations fell significantly during the first hours of fenoterol infusion. There was no increase of human placenta lactogen during the period of EPO increase. CONCLUSIONS: The data confirm our earlier results that fenoterol increases EPO concentrations following haemorrhage. In this model it was not necessary to stimulate EPO production prior to pharmacological treatment.

Detection and characterization of an ovine placental lactogen stable intermediate in the urea-induced unfolding process.

The urea-induced equilibrium unfolding of ovine placental lactogen, purified from ovine placenta, was followed by size-exclusion chromatography, far-UV CD, and intrinsic tryptophan fluorescence. The data obtained by each of these methods showed a poor fit to a two-state model involving only a native and an unfolded form. A satisfactory fit required, instead, a model that involved a stable, partially folded form in addition to the native and unfolded ones. The results obtained from the best-fitting theoretical curves for the three-state model indicated that this intermediate state, which is the predominant species in solution at 3.6 M of urea activity, is compact, largely alpha-helical, and changes considerably the native-like tertiary packing around its tryptophan residues. These findings suggest that this stable intermediate exhibits properties similar to those that characterize the molten globule state.

Lipopolysaccharides selectively inhibit mouse placental lactogen-II secretion through stimulation of interleukin-1 alpha (IL-1 alpha) and IL-6 production.

To determine whether lipopolysaccharides (LPS) regulate mouse placental lactogen-I (mPL-I), mPL-II, and mouse GHRF (mGHRF) secretion, mouse placental tissue from days 7, 9, and 12 of pregnancy was dispersed with collagenase and the purified trophoblast cells were cultured in a serum-free medium with or without LPS for 5 days. LPS significantly inhibited mPL-II secretion by cells from days 9 and 12 of pregnancy. However, LPS did not affect mPL-II secretion by cells from day 7 of pregnancy, mPL-I secretion by cells from days 7 and 9 of pregnancy, or mGHRF secretion by cells from day 12 of pregnancy. The inhibitory effect of LPS on mPL-II secretion by cells from day 12 of pregnancy was dose-dependent. Steady-state levels of mPL-II mRNA were significantly reduced by incubation of placental cells from day 12 of pregnancy with LPS. The inhibitory effect of LPS on mPL-II secretion was abolished by the addition of antibodies to IL-1 alpha and IL-6. These findings suggest that LPS selectively inhibit mPL-II secretion, at least partly through increases in IL-1 and IL-6 production, after midpregnancy.

The release of human chorionic gonadotrophin and placental lactogen by placental explants can be stimulated by Ca2+ entry through a Na(+)-Ca2+ exchange process.

Isosmotical replacement of extracellular Na+ ([Na+]o) by K+, choline and to a lesser extent by saccharose stimulated the release of chorionic gonadotrophin and placental lactogen from human term placental explants. The effect of [Na+]o removal on the release of both hormones was concentration-dependent and was inhibited in the absence of extracellular Ca2+ or in the presence of 0.5 mM Co2+, a Ca2+ entry blocker. Blockers of the voltage-sensitive Ca2+ channels (20 microM nifedipine and 50 microM methoxyverapamil) or Na+ channels (5 microM tetrodotoxin) did not affect the stimulatory effects of [Na+]o omission. By contrast, Mg2+ and Sr2+ (10 mM) as well as amiloride (2 mM) and its analogue 2',4'-dimethylbenzamil (50 microns), all known to affect the Na(+)-Ca2+ exchange, markedly reduced the increase in hormone release elicited by [Na+]o removal. Lastly, the secretory responses to [Na+]o deprivation were increased in the presence of 2 mM ouabain, an inhibitor of the Na(+)-K+ ATPase. These results indicate for the first time that [Na+]o omission provokes a Ca(2+)-dependent stimulation of human chorionic gonadotrophin and placental lactogen releases. The pharmacological dissection of the secretory effects of [Na+]o removal supports the existence of a process of Na(+)-Ca2+ exchange in placental cells.

Macrophage colony-stimulating factor induces the growth and differentiation of normal pregnancy human cytotrophoblast cells and hydatidiform moles but does not induce the growth and differentiation of choriocarcinoma cells.

In the present study, we examined whether or not macrophage colony-stimulating factor (M-CSF; CSF-1) is involved in the growth and differentiation of human chorionic, hydatidiform mole and choriocarcinoma cells. M-CSF promotes the growth of early gestation chorionic cells, hydatidiform mole cells, and a human term placenta cell line (tPA30-1). However, the growth of choriocarcinoma cells, BeWo, Jar, Jeg-3, and NUC-1, was not influenced at all by M-CSF. M-CSF promoted the secretion of human chorionic gonadotropin (hCG) and human placental lactogen (hPL), which are secreted from differentiated trophoblast, from early gestation chorionic cells and from hydatidiform mole cells. However, the secretion of hCG and hPL from choriocarcinoma cells was not affected by M-CSF. When M-CSF localization was examined by immunohistochemical staining, M-CSF was detected in chorionic and hydatidiform mole cells, but was absent in choriocarcinoma cells. These results suggest that the growth and differentiation of normal chorionic and hydatidiform mole cells are M-CSF-dependent, while the growth and differentiation of choriocarcinoma cells are not.