Oxytocin-induced prostaglandin F2 alpha release and endometrial oxytocin receptor concentrations throughout pregnancy in ewes. 1995

S Meier, and T M Lau, and G Jenkin, and R J Fairclough
Department of Physiology, Monash University, Clayton, Victoria, Australia.

Endometrial oxytocin receptor concentrations and oxytocin-induced plasma concentrations of 13,14,dihydro-15-keto prostaglandin F2 alpha were investigated on days 14 and 17 of the oestrous cycle and on days 14, 17, 25, 65, 85 and 145 of gestation in ewes. Total 13,14,dihydro-15-keto prostaglandin F2 alpha release in response to a bolus injection of oxytocin was significantly (P < 0.05) higher at luteolysis (day 17 of the oestrous cycle) than at any other stage of the oestrous cycle or in early gestation. On days 65, 85 and 145 of gestation, total prostaglandin release was significantly (P < 0.05) increased compared with earlier in gestation. Maximum concentrations of 13,14,dihydro-15-keto prostaglandin F2 alpha in response to oxytocin followed a similar pattern. Oxytocin receptor concentrations reflected total oxytocin-induced 13,14,dihydro-15-keto prostaglandin F2 alpha release, with increased oxytocin receptor concentrations occurring on day 17 of the oestrous cycle, compared with those observed on day 14 of the oestrous cycle and on days 14, 17 and 25 of gestation. By day 65 of gestation, oxytocin receptor concentrations were again increased. However, on days 85 and 145 of gestation, oxytocin receptor concentrations had decreased to concentrations similar to those observed in early gestation. These results indicate that oxytocin-induced 13,14,dihydro-15-keto prostaglandin F2 alpha release during early gestation is minimal despite the presence of endometrial oxytocin receptors. In mid-gestation, oxytocin-stimulated 13,14,dihydro-15-keto prostaglandin F2 alpha release is increased with a concomitant increase in uterine oxytocin receptor concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

UI MeSH Term Description Entries
D010121 Oxytocin A nonapeptide hormone released from the neurohypophysis (PITUITARY GLAND, POSTERIOR). It differs from VASOPRESSIN by two amino acids at residues 3 and 8. Oxytocin acts on SMOOTH MUSCLE CELLS, such as causing UTERINE CONTRACTIONS and MILK EJECTION. Ocytocin,Pitocin,Syntocinon
D011247 Pregnancy The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH. Gestation,Pregnancies
D011270 Pregnancy, Animal The process of bearing developing young (EMBRYOS or FETUSES) in utero in non-human mammals, beginning from FERTILIZATION to BIRTH. Animal Pregnancies,Animal Pregnancy,Pregnancies, Animal
D011374 Progesterone The major progestational steroid that is secreted primarily by the CORPUS LUTEUM and the PLACENTA. Progesterone acts on the UTERUS, the MAMMARY GLANDS and the BRAIN. It is required in EMBRYO IMPLANTATION; PREGNANCY maintenance, and the development of mammary tissue for MILK production. Progesterone, converted from PREGNENOLONE, also serves as an intermediate in the biosynthesis of GONADAL STEROID HORMONES and adrenal CORTICOSTEROIDS. Pregnenedione,Progesterone, (13 alpha,17 alpha)-(+-)-Isomer,Progesterone, (17 alpha)-Isomer,Progesterone, (9 beta,10 alpha)-Isomer
D004717 Endometrium The mucous membrane lining of the uterine cavity that is hormonally responsive during the MENSTRUAL CYCLE and PREGNANCY. The endometrium undergoes cyclic changes that characterize MENSTRUATION. After successful FERTILIZATION, it serves to sustain the developing embryo. Endometria
D005260 Female Females
D005865 Gestational Age The age of the conceptus, beginning from the time of FERTILIZATION. In clinical obstetrics, the gestational age is often estimated from the onset of the last MENSTRUATION which is about 2 weeks before OVULATION and fertilization. It is also estimated to begin from fertilization, estrus, coitus, or artificial insemination. Embryologic Age,Fetal Maturity, Chronologic,Chronologic Fetal Maturity,Fetal Age,Maturity, Chronologic Fetal,Age, Embryologic,Age, Fetal,Age, Gestational,Ages, Embryologic,Ages, Fetal,Ages, Gestational,Embryologic Ages,Fetal Ages,Gestational Ages
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D012756 Sheep Any of the ruminant mammals with curved horns in the genus Ovis, family Bovidae. They possess lachrymal grooves and interdigital glands, which are absent in GOATS. Ovis,Sheep, Dall,Dall Sheep,Ovis dalli
D015237 Dinoprost A naturally occurring prostaglandin that has oxytocic, luteolytic, and abortifacient activities. Due to its vasocontractile properties, the compound has a variety of other biological actions. PGF2,PGF2alpha,Prostaglandin F2,Prostaglandin F2alpha,9alpha,11beta-PGF2,Enzaprost F,Estrofan,PGF2 alpha,Prostaglandin F2 alpha,9alpha,11beta PGF2,F2 alpha, Prostaglandin,F2alpha, Prostaglandin,alpha, PGF2

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