title: Evidence for nitric oxide acting as a luteolytic factor in the human corpus luteum.
abstract: The aims of the present study were to characterize the expression and cellular localization of isoforms of nitric oxide synthase (NOS) in the human corpus luteum (CL) and to determine the effects of nitric oxide (NO) on CL steroidogenesis. Immunoblotting analyses revealed that endothelial NOS (eNOS) is the most abundant isoform in human CL with highest values during the late luteal phase. Immunoreactive eNOS was localized predominantely in the theca lutein layer, being particularly abundant in endothelial cells, but with positive staining also in some steroidogenic cells. Immunoreactive inducible NOS (iNOS) was also detected, but to lesser degree, and did not display apparent phase-specific changes. The effect of NO on CL steroid synthesis was examined using human chorionic gonadotrophin (HCG)-stimulated dispersed CL cells cultured in vitro. Progesterone production was significantly decreased (P < 0.05) by the NO donor spermine NONOate (10(-5) mol/l) in cells of the late, but not mid-, luteal phase. To investigate a potential link between NO and the local prostaglandins (PG), concentrations of PGF(2alpha) and PGE(2) were measured in culture medium. NO significantly increased (P < 0.05) concentrations of both PGF(2alpha) and PGE(2) during the late luteal phase. It is concluded that NO may be luteolytic in the human CL of menstruation.
authors.affiliation: Department of Obstetrics and Gynecology, Göteborg University, Sahlgrenska University Hospital, 413 45 Göteborg, Sweden.
authors.forename: B E
authors.initials: BE
authors.lastname: Fridén
authors.forename: E
authors.initials: E
authors.lastname: Runesson
authors.forename: M
authors.initials: M
authors.lastname: Hahlin
authors.forename: M
authors.initials: M
authors.lastname: Brännström
mesh_terms: D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000378:metabolism / Q000494:pharmacology; D003338:Corpus Luteum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015237:Dinoprost / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D005260:Female; D006801:Humans; D008183:Luteal Phase / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D011374:Progesterone / Q000096:biosynthesis; D013096:Spermine / Q000494:pharmacology
chemical_list: D006063:Chorionic Gonadotropin; D013096:Spermine; D009569:Nitric Oxide; D011374:Progesterone; D015237:Dinoprost; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D015232:Dinoprostone