The luteotropic activity of rat placenta is not due to a chorionic gonadotropin.
Placentae or uteri from pregnant rats (days 12-21) contained no detectable alpha-subunit of the glycoprotein hormones (CG, TSH, FSH, and LH) when assayed in either a rat or human alpha-RIA. The heads of rat fetuses contained increasing concentrations of alpha-subunit when assayed from days 12-20 of gestation (7.2-46 ng/g). Human term placenta contained large quantities of alpha-subunit (16,000 ng/g). alpha-Subunit was synthesized by the cell-free translation of poly(A)-enriched mRNA from mouse TSH-secreting pituitary tumor and human term placenta, but not from rat placentae or uterine implantation sites (days 11-21 of gestation). In addition, alpha mRNA was detected in mouse TSH-secreting pituitary tumor, rat pituitary, and human term placenta by hybridization to a 32P-labeled mouse alpha cDNA probe although no alpha mRNA could be detected in rat placentae (days 13-21 of gestation). The luteotropic activity found in pregnant rodents must be caused by a substance with a structure substantially distinct from any known gonadotropin.
D000818:Animals; D005260:Female; D015292:Glycoprotein Hormones, alpha Subunit; D006801:Humans; D010446:Peptide Fragments / Q000032:analysis*; D010908:Pituitary Hormones, Anterior / Q000032:analysis*; D010911:Pituitary Neoplasms / Q000032:analysis / Q000378:metabolism; D010920:Placenta / Q000032:analysis*; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D013972:Thyrotropin / Q000378:metabolism
D015292:Glycoprotein Hormones, alpha Subunit; D010446:Peptide Fragments; D010908:Pituitary Hormones, Anterior; D012333:RNA, Messenger; D013972:Thyrotropin