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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell-surface oxytocinase inactivates oxytocin and regulates oxytocin stimulation. We reported that oxytocinase in human endometrial epithelial cells was secreted from the cell membrane in the mid-secretory phase and disappeared from the cell surface. On the other hand, the production in human endometrium of prostaglandins, which play important roles in the reproductive process, has been reported to be upregulated by oxytocin. We investigated whether progesterone affects cell-surface oxytocinase and oxytocin-induced prostaglandin E2 (PGE2) production in vitro. Progesterone induced secretion of oxytocinase into the culture medium, which resulted in a decrease in cell-surface oxytocinase. Production of PGE2 was increased slightly by oxytocin without progesterone, and significantly with progesterone. The inhibition of oxytocinase activity by amastatin had a similar effect to the loss of cell-surface oxytocinase caused by progesterone. It is therefore likely that the cell-surface oxytocinase of endometrial epithelial cells modified by progesterone plays an important role in the function of the human endometrium through PGE2.
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PMID:Oxytocin-induced prostaglandin E2 (PGE2) synthesis is regulated by progesterone via oxytocinase in Ishikawa cells. 1570 31

Progesterone (P4) was found to interfere directly with the interaction of oxytocin (OT) with its own receptor in bovine endometrium. The aim of these studies was to investigate whether other steroids have a similar effect. Endometrial slices and epithelial endometrial cells from days 14 to 18 of the estrous cycle were used. Progesterone (P4), pregnenolone (P5), 17beta-hydroxyprogesterone (17-OHP4), the P4 receptor antagonist (aP4), and testosterone (T4) did not affect (P > 0.01) basal secretion of PGE2 and PGF 2alpha during 4h of incubation but all steroids inhibited (P < 0.05) OT-stimulated PGF2alpha secretion both from endometrial slices and from dispersed cells. None of the steroids used affected OT-stimulated PGE2 secretion from the cells (P > 0.01). In the next experiment it was studied whether P5, 17-OHP4 and P4 pretreatment for 30min modifies intracellular mobilization of Ca(2+) in response to OT. Oxytocin induced a rapid increase in intracellular Ca(2+)concentrations within 15s, while cells pretreated with steroids this increase occurred later. The total amount of intracellular Ca(2+)concentrations was lower (P < 0.05) in cells preincubated with steroids compared to controls. We conclude that steroids and aP4 are able to suppress OT-stimulated endometrial PGE2 and PGF2alpha secretion via a non-genomic pathway.
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PMID:Non-genomic effect of steroids on oxytocin-stimulated intracellular mobilization of calcium and on prostaglandin F2alpha and E2 secretion from bovine endometrial cells. 1596 66

The purpose of this overview is to highlight important steps of ovarian regulation during follicle development, ovulation and the life span of corpus luteum (CL) in ruminants. The ovarian cycle is central to reproductive function. It is characterized by repeating patterns of cellular proliferation, differentiation and transformation that encompass follicular development and ovulation as well as the formation, function and regression of the CL. In the first part, the importance and regulation of final follicle growth and especially of angiogenesis and blood flow during folliculogenesis, dominant follicle development and CL formation are described. Our results underline the importance of growth factors especially of insulin-like growth factor (IGF), vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) for development and completion of a dense network of capillaries (angiogenesis) during follicle growth and CL formation. In the second part, the regulation of CL function by endocrine/paracrine and autocrine acting regulators is discussed. There is evidence that besides the main endocrine hormones luteinizing hormone (LH) and growth hormone (GH) local regulators as growth factors, peptides, steroids and prostaglandins are important modulators of luteal function. During early CL development until midluteal stage oxytocin (OT), prostaglandins and progesterone (P) itself stimulate luteal cell proliferation and function supported by the luteotropic action of a number of growth factors. The still high mRNA expression, protein concentration and localization of VEGF, FGF and IGF family members in the cytoplasm of luteal cells during midluteal stage suggest that they play pivotal role in the maintenance (survival) of this endocrine tissue. The major function of the CL is to secrete P. Progesterone itself regulates the length of the estrous cycle via influencing the timing of the luteolytic PGF2alpha signal from the endometrium. At the end of a nonfertile cycle, the regression of CL commences, steroidogenic capacity is lost (functional luteolysis), cell death is initiated, and tissue involution as well as resorption occurs within a few days (structural luteolysis). The cascade of mediators during luteolysis is very complex and still awaits elucidation. Evidence is given for participation of blood flow, inflammatory cytokines, vasoactive peptides (angiotensin II and endothelin-1), and decrease of the classical luteotropic mediators.
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PMID:Ovarian function in ruminants. 1599 2

The objectives of this study were to determine the effects of buserelin or saline treatment on ovarian function (Experiment 1), plasma PGFM concentrations and oxytocin stimulated prostaglandin F(2alpha) (PGF(2alpha)) release (Experiment 2) in ewe lambs and ewes. Welsh Halfbred ewes (n=26) and ewe lambs (n=24) were mated to vasectomised rams at synchronised oestrus and on Day 12 post-mating each animal was injected intramuscularly either normal saline or 4 microg buserelin. In Experiment 1, plasma progesterone and oestradiol concentrations were determined in samples collected by jugular venepuncture 1h before and at 0, 2, 4, 6, 8, 24, 48 and 72 h after treatment (n=7 per treatment group). Progesterone concentrations increased (P<0.05) from 2 to 8h after buserelin treatment and returned to basal levels after 72 h, whereas oestradiol concentrations were maximal at 2h post-treatment and returned to basal levels after 24h (P<0.05). Oestradiol concentrations were lower (P<0.05) in buserelin-treated animals than controls at 72 h post-treatment. Basal and post-treatment progesterone concentrations were greater (P<0.05) in ewes than in ewe lambs but oestradiol levels were similar for both age groups. Ovulation rate, determined by laparoscopy on Day 14, was similar for both age groups (ewes 1.1; ewe lambs 1.0). Buserelin treatment induced accessory corpora lutea in ewes (4/7; 57%) but not in ewe lambs (0/7; 0%). In the Experiment 2, plasma PGFM concentrations were determined in samples collected at 20-min intervals for 6h on Day 14 and at 20-min intervals for 1h before and at 10-min intervals for 1h and then at 20-min intervals for a further 3h period after an intravenous injection of oxytocin (1IU/kg body weight) on Day 15 post-oestrus. In this experiment there were five ewe lambs and six ewes per treatment group. There was no effect of buserelin treatment or age on basal PGFM concentrations on either Day 14 or 15. Although peak PGFM concentrations tended to be lower in buserelin-treated animals, the difference was not significant (P>0.05). However, peak duration following oxytocin challenge on Day 15 post-mating was shorter (P<0.05) in control ewes compared with control ewe lambs. In conclusion, buserelin treatment given on Day 12 post-oestrus enhances luteal function more in ewes than ewe lambs and after a transitory increase, reduces oestradiol concentrations in both ewes and ewe lambs. However, buserelin treatment does not significantly attenuate the luteolytic signal.
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PMID:Effect of post-mating GnRH analogue (buserelin) treatment on PGF2alpha release in ewes and ewe lambs. 1625 49

The acute effects of prostaglandin F(2alpha) (PGF) on circulating oxytocin and progesterone concentrations were characterized in mares during the mid- or late-luteal phase. Pony mares were randomly assigned to the following experimental groups based on treatment with PGF (2.5mg) or saline on Day 8 or Day 13 (Day 0=ovulation): PGF-8, PGF-13, saline-8, or saline-13 (n=7/group). Mares were fitted with indwelling, jugular vein catheters and two blood samples (-5 and 0 min) were collected prior to treatment. Treatments were administered into the jugular vein (0 min) and blood collection continued thereafter at 1 min intervals until 5 min and then at 5 min intervals until 60 min. Based on the combined data of -5 and 0 min samples, mares on Day 8 had greater (P<0.05) oxytocin concentrations than mares on Day 13. On Day 8, PGF treatment resulted in a biphasic pattern of oxytocin release. Oxytocin concentrations increased (P<0.05) 1 min after PGF treatment, decreased (P<0.05) from 1 to 10 min, and increased (P<0.05) from 10 to 30 min. Oxytocin concentrations were greater (P<0.05) from 1 to 3 min in PGF-treated than saline-treated mares and at most sample times from 15 to 60 min. On Day 13, oxytocin concentrations were greater (P<0.05) in PGF-treated than in saline-treated mares for most sample times. Mares treated with PGF on Day 8 had greater (P<0.05) oxytocin concentrations at 25, 30, and 40 min than mares on Day 13. Progesterone concentrations on Day 8 also increased by 1 min after PGF, decreased toward basal concentrations by 2-3 min, and then increased to a maximum 10 min after treatment. Subsequently, circulating progesterone decreased (P<0.05) below pretreatment concentrations by 40-50 min after PGF. In conclusion, treatment with PGF resulted in an immediate and biphasic increase in progesterone concentrations prior to the expected decrease. Treatment of mares with PGF on Day 8 resulted in an overall greater increase in systemic oxytocin concentrations compared to treatment on Day 13, and the increase on Day 8 was biphasic.
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PMID:Acute effects of prostaglandin F(2alpha) on systemic oxytocin and progesterone concentrations during the mid- or late-luteal phase in mares. 1650 50

We investigated whether CIDR-based ovulation-synchronization protocols inhibit secretion of prostaglandin (PG) F2alpha from the uterus in the following luteal phase in non-cycling beef cows. Ten early (a month) postpartum non-cycling Japanese Black beef cows were treated with (1) Ovsynch (GnRH analogue on Day 0, PGF2alpha analogue on Day 7, and GnRH analogue on Day 9; n=3), (2) Ovsynch+CIDR (Ovsynch protocol plus a CIDR for 7 days from Day 0; n=4), or (3) estradiol benzoate (EB) Ovsynch+CIDR (EB on Day 0 in lieu of the first GnRH treatment followed by the Ovsynch+CIDR protocol; n=3). An oxytocin challenge was administered on Day 24 to examine uterine PGF2alpha secretion. Plasma concentrations of 13,14-dihydro-15-keto- PGF2alpha were lower at 30-120 min after oxytocin administration in the Ovsynch+CIDR group and 75 min after administration in the EB Ovsynch+CIDR group than in the Ovsynch group (P<0.05). Plasma progesterone concentrations were higher from Days 1 to 7 in the Ovsynch+CIDR group and from Days 1 to 5 in the EB Ovsynch+CIDR group than in the Ovsynch group (P<0.05). The progesterone concentrations were higher on Days 27 and 29 in both CIDR-treated groups than in the Ovsynch group (P<0.05). In conclusion, in non-cycling beef cows, CIDR-based ovulation-synchronization protocols inhibit uterine PGF2alpha secretion in the following luteal phase and prevent premature luteolysis as is seen with the Ovsynch protocol.
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PMID:Inhibitory effects of CIDR-based ovulation-synchronization protocols on uterine PGF2alpha secretion at the following luteal phase in early postpartum non-cycling beef cows. 1662 52

Six non-lactating Holstein cows were injected with 230 iu oxytocin subcutaneously twice daily from days 2 through 6 of the cycle. Controls (n=6) were given saline injections using the same schedule. Blood samples were collected at frequent intervals before and after each saline or oxytocin injection. Progesterone and 15-Keto-13, 14-dihydro prostaglandin F(2alpha) (PGFM), the major metabolite of prostaglandin F(2alpha), were analysed by radio-immunoassay. Oxytocin injections significantly increased plasma prostaglandin concentrations on days 2 and 3 when compared with the controls. In two oxytocin-treated cows, the cycle was shortened to 10 and 12 days. Estrus was preceded by a PGF(2alpha) release very similar to that preceding spontaneous estrus. Two of the oxytocin-treated cows showed estrus on day 21 and 22 preceded by luteolytic release of PGF(2alpha). Two oxytocin-treated cows developed cystic corpora lutea and had not shown heat when the ovaries were removed four weeks later. All oxytocin-treated cows showed a slower progesterone increase through day 8 than the controls. The study shows that endocrine events preceding cycle alterations in oxytocin-treated cows involve release of PGF(2alpha) and lowered levels of progesterone.
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PMID:Blood levels of progesterone and 15-Keto-13, 14-dihydro prostaglandin F(2alpha) during the estrous cycle of oxytocin-treated cows. 1672 65

Insulin-like growth factors 1 and 2 (IGF-1 and 2), oxytocin, progesterone, estradiol and ubiquitin were measured in bovine follicle-lutein-cysts and in follicular fluid after the classification of ovarian follicles by size (Class I = <4 mm; Class II = 5-8 mm; Class III = 9-12 mm; Class IV = preovulatory; Class V = cystic). It was found that IGF-1 concentrations increased during growth from 280 ng/ml in small follicles to 489 ng/ml in preovulatory follicles; IGF-2 appeared to remain constant in follicular fluid and in cysts (275 ng/ml). Oxytocin values were low in Class I, II and III follicles (30 pg/ml) but increased in preovulatory and cystic follicles (75 pg/ml). Estradiol increased significantly only in preovulatory follicles. Ubiquitin, a protein reflecting cellular replicative activity, could be found in bovine follicular fluid in high concentrations: 1.6 mug/ml in Class I,II and III follicles with the highest amounts in preovulatory follicles (2.3 mug/ml). In contrast with normal follicles, cysts were found to have a minimal concentration of ubiquitin (0.3 mug/ml). Progesterone levels were 5 times higher in cysts (325 ng/ml) and IGF-1 concentrations were markedly higher in cystic follicles (881 ng/ml) than in the other follicles. Simultaneously, maximum gene expression for IGF-1 was found in granulosa/lutein cells of cystic follicles (Class V), suggesting de novo synthesis of IGF-1. Between the different follicle classes progesterone, oxytocin and IGF-1 concentrations correlated positively (r=0.82). Hormonal levels in follicle-lutein-cysts indicated an arrested stage of insufficient luteinization as a possible result from the premature release of LH or from the release of amounts of LH inadequate to cause ovulation.
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PMID:A comparison of hormone levels in follicle-lutein-cysts and in normal bovine ovarian follicles. 1672 4

Adequate uterine contractility and periovulatory peristalsis, interpreted as "rapid sperm transport" to the side bearing the dominant follicle, may be a precondition for successful reproduction in humans. Estrogen and progesterone fluctuate characteristically during the menstrual cycle, and their source is the dominant follicle and corpus luteum. The question is, how is the direction to the left or right side of transport mechanisms influenced? An extracorporeal perfusion model of the swine uterus was used that maintained the uterus in a functional condition and that was suitable for the study of physiological questions. The effects of side-dependent estrogen, progesterone, and estrogen plus progesterone perfusion on oxytocin-induced uterine peristalsis were assessed using two intrauterine microcatheters placed in each horn of the swine uterus. Estrogen perfusion was associated with an increase in intrauterine pressure (IUP) in a dose-dependent manner only in the estrogen-perfused horn of the swine uterus. There was a significant difference between the IUP increase measured in the estrogen-perfused horn and that in the non estrogen-perfused horn of the swine uterus. Progesterone perfusion showed no effect in general. Furthermore, progesterone antagonized the estrogen effects. This study demonstrates that side-dependent estrogen perfusion resulted in side-dependent contractility in the swine uterus perfusion system used. These observations show that estrogen stimulates uterine contractility in the estrogen-perfused uterine horn and that estrogens may be the "trigger" for the transport mechanisms to the side bearing the dominant follicle during the periovulatory phase through their locally increased concentration and distribution via the utero-ovarian counter-current system in humans.
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PMID:Perfused non-pregnant swine uteri: a model for evaluating transport mechanisms to the side bearing the dominant follicle in humans. 1681 58

The present review highlights new information on pregnancy recognition and conceptus development and implantation in sheep with respect to regulation by progesterone, interferons and endogenous retroviruses. After formation of the corpus luteum, progesterone acts on the endometrium and stimulates blastocyst growth and elongation to a filamentous conceptus (embryo/fetus and associated extra-embryonic membranes). The envelope of endogenous retroviruses related to Jaagsiekte sheep retroviruses appears to intrinsically regulate mononuclear trophectoderm cell proliferation and differentiation into trophoblast giant binucleate cells. The mononuclear trophectoderm cells of elongating sheep conceptuses secrete interferon-tau, which acts on the endometrium to prevent development of the luteolytic mechanism by inhibiting transcription of the gene for the oestrogen receptor alpha in the luminal and superficial ductal glandular epithelia. These actions prevent oestrogen-induced transcription of the oxytocin receptor gene and, therefore, oxytocin-induced luteolytic pulses of prostaglandin F2alpha. Progesterone down regulation of its receptors in luminal and glandular epithelia correlates temporally with a reduction in anti-adhesive mucin land induction of secreted galectin 15 (LGALSI5) and secreted phosphoprotein 1, which are proposed to regulate trophectoderm proliferation and adhesion. Interferon-c acts on the endometrial lumenal epithelium to induce WNT7A and to stimulate LGALS 15, cathepsin L and cystatin C, which are candidate regulators of conceptus development and implantation. The number of potential contributors to maternal recognition and establishment of pregnancy continues to grow and this highlights our limited appreciation of the complexity of the key molecules and signal transduction pathways that intersect during these key developmental processes. The goal of improving reproductive efficiency by preventing embryonic losses that occur during the peri-implantation period of pregnancy in domestic ruminants provides the challenge to increase our knowledge of endometrial function and conceptus development.
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PMID:Pregnancy recognition and conceptus implantation in domestic ruminants: roles of progesterone, interferons and endogenous retroviruses. 1738 36


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