The Similarity of Chorionic Gonadotrophin and Its Subunits in Term Placentae from Man, Apes, Old and New World Monkeys and a Prosimian

Abstract

Chorionic gonadotrophin (CG) was estimated, by bioassay and radioimmunoassay (RIA), in placental extracts from 11 ape and monkey species. There was a significant correlation between the results of the two assay systems (r = 0.903, p < 0.001). The concentration of CG in most primate term placentae was the same as that in the human placenta at term. Extracts from all placentae cross-reacted with antiserum to ovine LH-β subunit, and those of the chimpanzee and gorilla also had a significant cross-reaction with an antiserum to the carboxyl terminal peptide of the HCG-β subunit. Primate placentae chromatographed on Sephadex G-200 had components active in the RIA systems for HCG, HCG-α HCG-β sub-units. In general, the elution profiles of all ape and monkey placental extracts resemble those made from human term placentae and of purified HCG and its subunits. The shape of the elution patterns from human and non-human material suggests that there was more than one molecular form of CG-α subunit activity. A second, more retarded molecular form having β subunit activity was found in extracts made from human, gorilla, gibbon and rhesus monkey placentae. The similarity between the structure of ape and monkey placental CG with HCG and its subunits implies a function similar to that of HCG in late pregnancy.

Chorionic gonadotrophin beta subunit mRNA but not luteinising hormone beta subunit mRNA is expressed in the pituitary of the common marmoset (Callithrix jacchus)

“…Its small size and easy reproduction in captivity are considered an advantage for studies in non-human primates (Smith et al 2001, Zuehlke & Weinbauer 2003. Marmoset placental CG has been the subject of several studies in the past (Hobson & Wide 1981, Saunders et al 1987, Rosenbusch et al 1994, Simula et al 1995, whereas the genomic sequence of mLH was unknown. In the present work we used intergenic PCR to demonstrate the existence of both mCG and mLH subunit genes, separated by an intronic sequence of approximately 20 kb, with CG placed 5 of the LH gene.…”

“…In primates there are two pituitary gonadotrophins, luteinising hormone (LH) and follicle-stimulating hormone (FSH), and one gonadotrophin of placental origin, the chorionic gonadotrophin (CG) (Hobson & Wide 1981, Dufau 1998, Weinbauer et al 2000. The general functions of LH and FSH are the regulation of gametogenesis in the testis and ovary, whereas CG rescues the corpus luteum and maintains pregnancy.…”

“…Sequence information for many primate gonadotrophins is available today (Maston & Ruvolo 2002), mostly from Old World monkeys (Schmidt et al 1999). In some species, such as the marmoset monkey (Callithrix jacchus), an important animal model for human reproduction, CG has already been characterised and cloned (Hobson & Wide 1981, Simula et al 1995 from the trophoblast cells of the placenta, whereas the sequence and pattern of expression of the LH subunit remain unknown.…”

Gonadotrophic activity of the guinea-pig placenta during pregnancy

“…This indicates that in women and guinea-pigs these components are of a similar molecular size. Placental extracts from several mammalian species, made and examined by the same methods, behave similarly (Wide & Hobson, 1978;Hobson & Wide, 1981). Bland & Donovan (1969) concluded that the guinea-pig placenta appears to produce a systemically active substance capable of neutralizing the luteolytic abilities of the uterus.…”

Evaluation of Seven Test Kits for the Detection of Pregnancies in the Common Marmoset, Callithrix jacchus

“…A good cross-reactivity of CG from marmosets to antisera raised against the p-subunit of LH and urinary CG of man, gorillas, orang utans, and chimpan zees was observed [9], Extracts from term placentae of 11 ape and monkey species, including the marmoset, revealed structural similarity between CG and simian placental gonadotropin [10]. In this study, cross-reac tivity with HCG-a and HCG-P (by solid phase radioimmunoassays) and with antise rum to ovine LH-a and LH-p subunit (in haemagglutination inhibition test) was mea sured.…”