title: Absence of the oxytocin-induced prostaglandin F2 alpha secretory response in uterus from ovariectomized ewes and activation of the response in vitro.
abstract: Oxytocin-induced prostaglandin F2 alpha (PGF2 alpha) responses were measured in explants of uterus from ovariectomized ewes on the day of tissue collection or after culture for 72 h in the presence or absence of oestradiol-17 beta (100 nmol/l). Oxytocin receptor binding activity was 210 +/- 47 fmol [3H]oxytocin bound per mg protein in fresh tissue and 89 +/- 24 and 90 +/- 17 fmol/mg in tissue cultured with control medium or with oestradiol respectively (means +/- S.E.M.). PGF2 alpha production during the hour following oxytocin administration to freshly collected tissue was 272 +/- 77 ng/g/h compared with 193 +/- 35 ng/g/h in the absence of oxytocin. These rates were 2789 +/- 1085 and 353 +/- 135 ng/g/h after culture for 72 h in control medium and 2022 +/- 496 and 342 +/- 134 ng/g/h after culture with oestradiol. Thus oestradiol had no effect on the culture-induced maturation of the PGF2 alpha response. Short-term exposure to arachidonic acid (66 mumol/l) did not increase PGF2 alpha production in fresh tissue but significantly increased basal but not oxytocin-induced PGF2 alpha production after 72 h in culture (P < 0.05). There was an absence of oxytocin-induced inositol phosphate turnover in fresh tissue but after culture concentrations of inositol mono-, bis- and trisphosphates were all significantly increased by oxytocin (P < 0.005). Antisera directed against G-protein alpha sub-units alpha i3, alpha o, alpha q, alpha 11 and the common beta subunit, and prostaglandin H-synthase-1 detected proteins that were present before and after culture.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Cellular Physiology, Babraham Institute, Cambridge, UK.
authors.forename: E L
authors.initials: EL
authors.lastname: Sheldrick
authors.forename: H C
authors.initials: HC
authors.lastname: Flick-Smith
authors.forename: D E
authors.initials: DE
authors.lastname: Bendall
authors.forename: A P
authors.initials: AP
authors.lastname: Flint
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology; D046508:Culture Techniques; D015237:Dinoprost / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism; D015151:Immunoblotting; D007295:Inositol Phosphates / Q000378:metabolism; D010052:Ovariectomy; D010121:Oxytocin / Q000494:pharmacology*; D010716:Phosphatidylinositols / Q000378:metabolism; D018045:Receptors, Oxytocin / Q000378:metabolism; D012756:Sheep / Q000502:physiology*; D014599:Uterus / Q000187:drug effects / Q000378:metabolism*
chemical_list: D007295:Inositol Phosphates; D010716:Phosphatidylinositols; D018045:Receptors, Oxytocin; D016718:Arachidonic Acid; D010121:Oxytocin; D015237:Dinoprost; D019204:GTP-Binding Proteins