title: Luteinizing hormone-releasing hormone (LHRH)- and (hydroxyproline9)LHRH-stimulated human chorionic gonadotropin secretion from perifused first trimester placental cells.
abstract: (Hydroxyproline9)LHRH [(Hyp9)LHRH] has been isolated from human, sheep, rodent, and frog hypothalamus. (Hyp9)LHRH is the major LHRH moiety in fetal rat hypothalamus. This study compared 1) synthetic LHRH-stimulated hCG secretion from term trophoblast vs. first trimester placental cells and 2) the ability and specificity with which synthetic LHRH and (Hyp9)LHRH could stimulate hCG secretion from 8- to 12-week gestation placenta. Physically dissociated cells from multiple placentae were pooled, plated on microcarrier beads, and perifused in 1.5-ml chambers (1.5 x 10(6) cells/chamber). Effluent fractions were analyzed for hCG. Each chamber was its own control. Basal hCG secretion did not depend upon exogenous LHRH stimulation. The amplitude of LHRH-stimulated hCG pulses was greater from first trimester placental than term trophoblast cells (mean +/- SEM, 6.99 +/- 1.47 vs. 0.50 +/- 0.05 mIU/ml perifusate; peak minus basal; n = 4 chambers; P less than 0.01). LHRH and (Hyp9)LHRH (10(-9) M) increased hCG secretion from first trimester placental cells (5.02 +/- 1.29 vs. 8.64 +/- 1.61 and 4.36 +/- 0.58 vs. 7.44 +/- 1.01 mIU/ml; n = 15 and 9, respectively; P less than 0.01). At the concentrations used, LHRH and (Hyp9)LHRH seemed to stimulate hCG secretion equipotently (P greater than 0.05). Simultaneous perifusion with an LHRH antagonist, (Nal-Glu)LHRH blocked the hCG secretory response to LHRH or (Hyp9)LHRH (equimolar 10(-9) M concentrations; n = 5; P less than 0.05). (Nal-Glu)LHRH alone (10(-9) M) did not affect hCG secretion (n = 5; P greater than 0.05). The results suggested that first trimester placental cells are more responsive to LHRH than are term trophoblast cells. (Hyp9)LHRH is a potential physiological secretagogue of hCG.
authors.affiliation: Department of Obstetrics and Gynecology, Grace Hospital, University of British Columbia, Vancouver, Canada.
authors.forename: W D
authors.initials: WD
authors.lastname: Currie
authors.forename: G L
authors.initials: GL
authors.lastname: Steele
authors.forename: B H
authors.initials: BH
authors.lastname: Yuen
authors.forename: C
authors.initials: C
authors.lastname: Kordon
authors.forename: J P
authors.initials: JP
authors.lastname: Gautron
authors.forename: P C
authors.initials: PC
authors.lastname: Leung
mesh_terms: D006063:Chorionic Gonadotropin / Q000378:metabolism*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D010477:Perfusion; D010920:Placenta / Q000187:drug effects / Q000378:metabolism*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D013997:Time Factors
chemical_list: D006063:Chorionic Gonadotropin; D007987:Gonadotropin-Releasing Hormone; C074293:LHRH, hydroxyprolyl(9)-