title: Regulation of human placental trophoblast low-density lipoprotein uptake in vitro by estrogen.
abstract: In the present study, human trophoblast cells were studied in culture to determine the effect of estrogen on low-density lipoprotein (LDL) uptake and progesterone formation. Cytotrophoblasts were obtained from term human placentas and incubated for 72 h with 10% FBS to stimulate formation of syncytia. Syncytiotrophoblasts were then incubated for an additional 48 h with estradiol and/or LDL protein. Estradiol plus LDL stimulated progesterone to a level that was 133% greater (P < 0.05) than control (314 +/- 69 ng/mg protein) or LDL alone, suggesting that estrogen stimulated progesterone formation via an increase in LDL uptake and utilization. To examine this possibility, trophoblast cells were cultured with estradiol for 48 h as above, then incubated for 12 h with 6-200 micrograms/mL [125I]LDL. Mean (+/- SE) specific uptake of [125I]LDL (ng/mg cell protein) was approximately 50% greater (P < 0.01) with estradiol (638 +/- 23) than with vehicle (429 +/- 54). Scatchard analysis demonstrated that the dissociation constant for LDL uptake was similar in the presence (2.9 +/- 0.4 x 10(-6)M) and absence (2.8 +/- 0.6 x 10(-8)M) of estradiol, indicating that estrogen increased LDL receptor number without affecting affinity. LDL uptake was increased (P < 0.05) by incubating trophoblast with as little as 0.10 ng/mL estradiol (approximately 10(-9) M). We conclude that estrogen regulates placental trophoblast cell uptake of LDL and, thus, the availability of cholesterol for progesterone bio-synthesis during human pregnancy.
authors.affiliation: Department of Obstetrics/Gynecology, University of Maryland School of Medicine, Baltimore 21201, USA.
authors.forename: R W
authors.initials: RW
authors.lastname: Grimes
authors.forename: G J
authors.initials: GJ
authors.lastname: Pepe
authors.forename: E D
authors.initials: ED
authors.lastname: Albrecht
mesh_terms: D008078:Cholesterol, LDL / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008077:Lipoproteins, LDL / Q000378:metabolism* / Q000494:pharmacology; D011247:Pregnancy; D011374:Progesterone / Q000096:biosynthesis; D014327:Trophoblasts / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D008078:Cholesterol, LDL; D007457:Iodine Radioisotopes; D008077:Lipoproteins, LDL; D011374:Progesterone; D004958:Estradiol