Placental production of human chorionic gonadotrophin α and β subunits in early pregnancy as evidenced in fluid from the exocoelomic cavity

Abstract

Levels of human chorionic gonadotrophin (hCG) and of its free alpha and beta subunits were measured using specific immunoradiometric assays in exocoelomic fluid (ECF) and maternal serum (MS) collected from five pregnant women at 6.6-8 weeks of gestation. Mean levels of hCG and its free subunits were significantly (P < 0.001) higher in ECF than in MS: 3.5-fold for hCG, 600-fold for free alpha hCG and 38-fold for beta hCG. There was no correlation between either hCG levels or levels of its free subunits in ECF and MS. On a molar basis, the quantity of free alpha hCG subunit expressed as a percentage of the total (free+combined) amount was 83% in ECF and 2.7% in MS (P < 0.001). The amount of free beta hCG subunit as a percentage of the total was 22% in ECF and 3.5% in MS (P < 0.001). The ratio of the total amounts of alpha- and beta hCG subunits amounted to 4.6 in ECF and 0.99 in MS (P < 0.001). The heterogeneity of hCG was further investigated by polyacrylamide gel electrophoresis followed by immunoblotting. Several bands with molecular mass ranging from 42 to 57 kDa, corresponding to hCG dimers, were immunodetected in ECF and MS with anti-alpha hCG and anti-beta hCG monoclonal antibodies. A free 35 kDa beta hCG immunoreactive band was found in ECF and MS. A free alpha hCG immunoreactive band was observed at 23 kDa in ECF and at 21 kDa in MS. These findings suggest that the exocoelomic cavity is a reservoir where hCG and its subunits produced by trophoblast accumulate directly.(ABSTRACT TRUNCATED AT 250 WORDS)

An Investigation of the Single and Combined Phthalate Metabolite Effects on Human Chorionic Gonadotropin Expression in Placental Cells

“…Sex and gestational variation in hCG have been previously established at the population level in analyses of hCG biomarker data ( Adibi et al 2015b ; Bremme and Eneroth 1983 ; Buckberry et al 2014 ; Clements et al 1976 ; Cowans et al 2009 ; Nagy et al 1994a , 1994b ; Steier et al 1999 ; Yaron et al 2002a ). This type of variation is generally not considered when analyzing in vitro experimental data.…”

The role of glycosylation in regulating the glycoprotein hormone free alpha-subunit and free beta-subunit combination in the extraembryonic coelomic fluid of early pregnancy.

“…The expansion and obliteration of the EEC also coincides with the rise and fall in concentrations of HCG in the first trimester, leading to the suggestion that a tissue closely associated with the EEC (probably the chorion) is the principle source of HCG (Chard et al, 1995). It is notable that concentrations of HCG and its subunits are strikingly higher in the EEC than elsewhere, including maternal blood (Hes et al, 1992;Nagy et al, 1994;Jauniaux et al, 1995).…”