title: Gonadotropin and lipoprotein receptor levels in rat luteal cells of early pregnancy.
abstract: Dispersed cells from rat corpora lutea isolated on pregnancy days, 5, 7, 10 and 13, yielded three distinct sub-populations of luteal cells when centrifuged in a continuous, 0-40%, Metrizamide density gradient. Bands I and II (refract. ind. 1.340-1.346) constituted highly enriched, functional, luteal cell fractions. The more dense fraction (Band III, refract. ind. 1.348-1.355), while contaminated with non-luteal cells, also contained cells capable of progesterone production. Progesterone synthesis by all three sub-populations was stimulated by LH, and each sub-population bound [125I]-labeled hCG and [125I]-labeled HDL with high affinity. However, the concentrations of LH/hCG and lipoprotein binding sites were greater in Band I + II than in Band III. Progesterone secretion during the selected days of pregnancy, being high on days 5 and 13 with a nadir on day 10, was shown to correlate with the concentration of LH/hCG-binding sites present on Band I + II cells. This correlation was not seen when comparing Band III cells. The concentration of HDL-binding sites did not vary significantly with the sub-populations of luteal cells isolated on the selected days of pregnancy.
mesh_terms: D000818:Animals; D002352:Carrier Proteins; D006063:Chorionic Gonadotropin / Q000378:metabolism*; D003338:Corpus Luteum / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D007700:Kinetics; D008075:Lipoproteins, HDL / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008854:Microscopy, Electron; D011247:Pregnancy; D011374:Progesterone / Q000378:metabolism; D016601:RNA-Binding Proteins; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011974:Receptors, LH; D018110:Receptors, Lipoprotein
chemical_list: D002352:Carrier Proteins; D006063:Chorionic Gonadotropin; D008075:Lipoproteins, HDL; D016601:RNA-Binding Proteins; D011956:Receptors, Cell Surface; D011974:Receptors, LH; D018110:Receptors, Lipoprotein; C031616:high density lipoprotein receptors; C075197:high density lipoprotein binding protein; D011374:Progesterone; D007986:Luteinizing Hormone