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

In cases of missed abortion and missed labor, labor was induced by PGF2 alpha i.a., i.v. and by oxytocin infusion. Platelet function (methods of Born and Breddin), the coagulation system and fibrinolysis have been studied within the three groups. Using PGF 2 alpha i.v., the initially increased platelet aggregation showed a tendency to become normal. There was no manifestation of activation of the coagulation system. Fibrinolytic activity showed a slight increase during PGF2 alpha i.v. No essential changes in platelet function, coagulation and fibrinolytic system were found after i.a. injection of PGF2 alpha. When inducing labor by oxytocin i.v., both the coagulation and the fibrinolytic system were slightly activated and platelet aggregation increased. The results and their clinical importance for hemostasis as well as therapeutic consequences are discussed.
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PMID:Platelet function, coagulation and fibrinolysis during termination of missed abortion and missed labor by PGF2 alpha and oxytocin. 52 69

Six heifers with normal oestrous cycles were treated i.m. with 100 i.u. oxytocin on 3 consecutive days, commencing on Days 1-6 after oestrus, and the levels of prostaglandin (PG) F in posterior vena cava plasma were compared with pretreatment values. An increase of PGF in response to oxytocin was significantly influenced by day, with the greatest response occurring on Day 3 after oestrus. In an ovariectomized heifer the levels of PGF in posterior vena cava plasma increased 24 h after priming with oestradiol, but no further increase occurred after oxytocin injection. Peak levels of PGF were higher in the plasma of the posterior vena cava than in the jugular vein. Various storage conditions of the blood before centrifugation and freezing (--20 degrees C) produced significant differences in plasma levels of endogenous PGF, but storage experiments with added labelled PGF-2alpha indicated that the PG was stable in plasma and whole blood.
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PMID:The effect of oxytocin treatment on the levels of prostaglandin F in the blood of heifers. 55 71

Isolated uteri from rats with regular 4-day cycles were incubated in Krebs-Ringer bicarbonate buffer and the release of PGF into the medium was measured by radioimmunoassay after extraction of the incubation medium with ethyl acetate at pH 3.0-3.5. PGF was produced from endogenous precursors and accumulated in equal amounts in the medium during two successive 60 min periods on each day of cycle, but the magnitude of the production varied significantly during the cycle, being greatest in estrus. Oxytocin in doses up to 500 mU/ml had no effect on PGF accumulation in the incubation period at any stage of the cycle, while epinephrine (10(-3)) greatly stimulated PGF release from the estrous uterus but had no effect on PGF release from the diestrous uterus. Phentolamine, an alpha-blocking agent, had no effect on the epinephrine-induced release of PGF, while propranolol, a beta-blocking agent, not only prevented in increase in PGF production induced by epinephrine but also reduced the basal release of PGF by the estrous uterus. Since oxytocin contracts and epinephrine relaxes the nonpregnant rat uterus both in vivo and in vitro, it is unlikely that the effects of these two compounds on uterine contractility are mediated by the release of PGF2alpha.
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PMID:Effects of epinephrine and oxytocin on the release of prostaglandin F from the rat uterus in vitro. 56 31

A single i.m. injection of 5 mg PGF-2 alpha evoked a significant elevation of plasma oxytocin values in sows 6 days post partum and during dioestrus. Plasma vasopressin levels in dioestrous sows were not significantly affected by PGF-2 alpha. It is concluded that circulating steroid levels do not interfere with the response of oxytocin levels to PGF-2 alpha.
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PMID:Plasma oxytocin and vasopressin concentrations in response to prostaglandin injection into the pig. 57 27

Uterine responses to vasopressin and oxytocin were monitored in non-pregnant and 3- or 6-8-day-pregnant rabbits by recording the intrauterine pressure. Oxytocin stimulated uterine activity in all groups, but the effect of vasopressin was stimulatory in non-pregnant animals, inhibitory in those 3 days post coitum and weakly stimulatory in those later in pregnancy. Inhibition of prostaglandin (PG) synthesis, by the administration of indomethacin, reduced the spontaneous uterine activity as well as the responses to oxytocin and vasopressin in the non-pregnant rabbits, but had little effect in the pregnant animals. During infusion of PGF-2alpha, PGE-1 or PGE-2 in 6-8-day-pregnant rabbits, the stimulatory response to vasopressin, although slight before the infusion, was inhibited whereas the stimulatory response to oxytocin remained virtually unchanged. The results suggest that vasopressin and oxytocin under certain hormonal conditions, are able to activated the uterine contractions by mechanisms in which the involvement of PG is not obligatory.
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PMID:Differences in the effects of vasopressin and oxytocin on rabbit myometrial activity and a possible mediation of prostaglandins. 59 88

Intrauterine pressure was monitored in vivo in oestrogen-treated ovariectomized ewes before, during and after treatment with progesterone (50 mg s.c./day for 3 days). Progesterone reversibly reduced the frequency and amplitude of myometrial activity and abolished uterine reactivity to oxytocin (i.v.) and PGF-2alpha (intrauterine infusion). The rate of rise of intrauterine pressure during active pressure cycles was significantly reduced. These results confirm that the action of progesterone on the ovine myometrium is comparable to the classic progesterone 'block'. The intrauterine infusion of PGF-2alpha (10 microgram/min), which elicited a marked mechanical response in the control animals, failed to stimulate the progesterone-'blocked' uterus, suggesting that the inhibition produced by progesterone is due to a direct action of the hormone on the uterine muscle and not to an indirect mechanism operating through endometrial prostaglandin output.
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PMID:Demonstration that progesterone 'blocks' uterine activity in the ewe in vivo by a direct action on the myometrium. 62 2

Contractility parameters (uterine activity, contraction interval, amplitude, and frequency of contractions) were analyzed quantitatively during the active phase of first-stage of labour in 60 clinically normal term nulliparae with spontaneous or induced labour. Inductions were surgical (amniotomy alone) or by amniotomy combined with either intravenous oxytocin or prostaglandin administered intravenously (PGF 2alpha or PGE 2) or orally (PGE 2).
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PMID:Uterine contractility in spontaneous and induced labour. 98 99

Early corpus luteum development in nonpregnant and pregnant goats was characterized by a steady increase in peripheral plasma concentrations of progesterone and a high release of prostacyclin (PGI-2) but low release of prostaglandin F-2 alpha (PGF-2 alpha). Jugular administration of oxytocin antagonist (OXA) (0.2 microgram/kg/day) on the day of oestrus and for 3 days thereafter to cyclic and mated goats, significantly (P less than 0.001) inhibited progesterone and prostaglandin secretion and reduced conception rate. Co-administration of PGI-2 (200 micrograms/day) with OXA resulted in a steady increase of progesterone and establishment of pregnancy, but co-administration of PGF-2 alpha (175 micrograms/day) with OXA had no effect. It is suggested that oxytocin is required for early development of the corpus luteum and such effects may be mediated via PGI-2 production.
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PMID:Inhibition of luteal function by oxytocin antagonist in goats (Capra hircus). 155 89

Corpora lutea (CL) of a number of species produce oxytocin (OXT). In the present experiments we studied basal, prostaglandin (PG) F2 alpha-stimulated and ascorbate-stimulated OXT release from individual bovine luteal cells utilizing the reverse hemolytic plaque assay (RHPA). Using a mixture of C- and N-terminus-specific antisera against OXT, we were able to demonstrate OXT plaque formation by individual luteal cells. CL consist of two steroidogenic cell types: large luteal cells (LLC), believed to derive from granulosa cells and to produce and secrete OXT, and small luteal cells (SLC), thought to derive from theca cells. To distinguish between these two cell types, we designated cells greater than 20 microns as LLC and those less than 20 microns as SLC. On the basis of this morphological parameter, OXT release from both LLC and SLC was demonstrable. After an incubation period of 15 h, 7% of both cell types formed OXT plaques. PGF 2 alpha and ascorbate increased the size of plaques surrounding both LLC and SLC to more than 200% and 240%, respectively (basal plaque size = 100%). The number of plaque-forming cells increased only slightly in the presence of either PGF 2 alpha or ascorbate in comparison to basal conditions. We suggest that the RHPA can be used to demonstrate peptide release from luteal cells. It is concluded that LLC may be subdivided into functional subclasses because less than 10% of bovine luteal cells release OXT. Known OXT secretagogues increased the amount of OXT released. It appears that not only LLC but also SLC secrete this peptide.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Demonstration of oxytocin release by bovine luteal cells utilizing the reverse hemolytic plaque assay. 161 14

The purpose of the present investigation was to test the hypothesis that drug-induced changes in rumen contractions influence feed intake in dwarf goats. Intravenous (i.v.) administration of clonidine (1 microgram kg-1 min-1 for 10 min), xylazine (1 microgram kg-1 min-1 for 10 min), and PGF-2 alpha (10 micrograms kg-1 min-1 for 15 min) caused bradycardia and inhibition of rumen contractions. However, no appetite-stimulating effect of these drugs was observed. Other clinical changes induced by the alpha-adrenergic agonists included slight sedation and a decrease in body temperature; all clinical effects of clonidine and xylazine were partly antagonized by tolazoline pretreatment (10 micrograms kg-1 min-1 for 30 min). These results suggest that the CNS control of feeding differs in ruminants and monogastric species. In dwarf goats fasted for 2 h, i.v. administration of oxytocin (0.01 IU kg-1 min-1 for 15 min), vasopressin (0.01 IU kg-1 min-1 for 15 min), octapressin (0.003 IU kg-1 min-1 for 15 min) or PGE1 (0.8 microgram kg-1 min-1 for 15 min) did not change feeding behaviour during the two observation periods (0-30 min and 180-210 min after drug infusion, respectively). In previous studies, similar doses of these drugs induced changes in heart rate and inhibition of rumen contraction in goats. These findings demonstrate that drug-induced changes in forestomach contractions do not simply cause changes in feeding behaviour. The i.v. infusion of the PGF 2 alpha analogues etiproston (10 micrograms kg-1 min-1 for 15 min), luprostiol (30 micrograms kg-1 min-1 for 15 min), cloprostenol (1 microgram kg-1 min-1 for 15 min) and tiaprost (1 microgram kg-1 min-1 for 15 min) induced hypophagic effects and stimulated intestinal propulsion.
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PMID:Feed intake and rumen motility in dwarf goats. Effects of some alpha 2-adrenergic agonists, prostaglandins and posterior pituitary hormones. 167 5


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