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

PGE2 (prostaglandin E2) had been successfully used in initiating labor in term pregnancies (Karim and Sharma, 1971). This study evaluates the safety and efficacy of prostaglandin for induction of labor in 23 patients (gestational length, 38-41 weeks; mean age, 27; age range, 17 to 40; parity 0 to 6). 20 received an oral PGE2 0.5 mg tablet hourly while 3 received an initial dose of 0.5 mg with 0.5 mg incremental increase hourly. 20 patients delivered vaginally liveborn infants without neonatal depression according to Apgar score and subsequent behavior in the nursery. 2 patients delivered by C-section and 1 was excluded from the study because of inadequate duration of treatment. Mean time to delivery was 5 hours, 47 minutes; mean drug dose, 2.53 mg. Mild transient emesis and diarrhea occurred in 2 patients, and emesis only in 1. Bishop induction score did not correlate with total dose of PGE2 used. Parity correlated negatively with dose necessary to achieve delivery (p0.05). The findings confirm the efficacy and safety of oral PGE, which provides an alternate drug and route for induction of labor. Oxytocin induction is briefly compared with prostaglandin induction.
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PMID:Oral prostaglandin E2 for induction of labor. 482 94

Prostaglandins (PGs) are fatty acids containing a cyclopentane ring. They occur in relatively high concentrations in sperm and in lower concentrations in the endometrium, amniotic fluid, and menstrual blood. In addition, PGs have been demonstrated in a number of tissues other than the reproductive organs. PGs increase the activity of the myometrium both during pregnancy and in the nonpregnancy state. Among the various forms of PG, PGE, and PGF2alpha in particular have been investigated. These PGs act equally potently on the nonpregnant uterus but PGE acts approximately 8-10 times as potently as PGF2alpha on the pregnant uterus. PGs may be employed to induce abortion by either intravenous, intrauterine, or intravaginal administration. The intravenous method is most useful as the dosage can be kept low enough to avoid generalized side effects. PGs may be particularly useful in the second trimester when the fetus is too large to be removed by vacuum aspiration. PGs may be employed to induce labor but no convincing evidence is available to show that the preparations have advantages over oxytocin at term. On the other hand, it will probably be possible to employ PGs for induction of labor before term when oxytocin is less effective. For the same reason, PGs are suitable for induction of abortion in cases of missed abortion and fetal death. It is probable that PGs can be developed as a contraceptive measure to be employed in the 2nd 1/2 of the cycle or as a very early abortion-producing preparation in the 1st days after a missed menstrual period. The significance of PGs in connection with infertility is not yet clear but reduced PG values in sperm have been found in the male of infertile couples. (Author's modified)
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PMID:[Utilization of prostaglandins in gynecology and obstetrics]. 502 2

A review of early research (up through 1970) on prostaglandins (PGs) is presented. Their chemical structure and classification based on their ring-structure is detailed as well as various analytic methods of mammalian tissues and body fluids. For clinical use PGE1 and 2, PGF2alpha and PGA1 are the most significant ones because of their properties. PGs have many physiological activities encompassing many organ systems. Their pharmacological actions include: 1) stimulation of nonvascular smooth muscle; 2) peripheral vasodilation (excluding PGFs which cause vasoconstriction); 3) inhibition of lipolysis; 4) inhibition of platelet aggregation; 5) inhibition of gastric peristalsis and gastric juice secretion; 6) bronchodilation; and 7) inhibition of spontaneous CNS activity. The level of PGEs in semen is closely related to the degree of fertility; normally fertile men have 55 mcg PGE/ml and never less than 11 mcg/ml. Current studies are under way on the effect of PGE in artificial insemination of sperm of subfertile men. PGF2alpha and PGE2 stimulate menstruation and uterine contraction; other PGs inhibit uterine contraction. PGs from semen have a role in sperm transport and possibly act on fallopian tube motility aiding sperm capacitation, and ovum retention and transport. Early trials with PGs point to a possible action as an abortifacient, as a once-a-month contraceptive, or a postconception contraceptive agent. PGF2alpha is found in variable concentrations in maternal blood during contraction of the pregnant uterus; levels increase as labor progresses. PGs have been used for labor induction, for induction of abortion and in mole pregnancy. Given as a constant intravenous infusion they produce regular contractions leading to natural expulsion of the fetus and causing very few side effects in the woman with no adverse effects on the fetus. PGs' action compares favorably with that of oxytocin and is preferable for labor induction in certain pregnancy complications. PGE1 and 2 have a stronger effect than PGF2alpha, hence can be used in smaller dosage and cause fewer adverse effects.
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PMID:[Prostaglandins in gynecology and obstetrics]. 505 16

The interrelationship of several physiological receptors which influence the hydroosmotic response of the toad urinary bladder was studied employing neurohypophyseal peptides, prostaglandin E(1), theophylline, and cyclic nucleotides. The binding property of agonists (pD(2)), synergists (pS(2)), competitive antagonists (pA(2)), and noncompetitive antagonists (pD(2)') was determined after a suitable methodology had been developed. A series of neurohypophyseal peptides was examined in detail for their catalytic activity. It was found that the replacement of the hydroxy radical of the tyrosine residue in oxytocin by a methoxy and then by an ethoxy radical led to a progressive decline in the catalytic activity of the hormone-corresponding to a change from agonist to partial agonist to competitive antagonist. [4-Leucine]-mesotocin behaved as a competitive antagonist of oxytocin. Prostaglandin E(1) (PGE(1)) was found to be a noncompetitive inhibitor of neurohypophyseal peptides and theophylline; whereas the maximal hydroosmotic response of the bladder to [2-O-methyltyrosine]-oxytocin and theophylline was greatly depressed by PGE(1), the response to saturating concentrations of oxytocin was only slightly diminished-a finding which reveals a "receptor reserve" for oxytocin. Saturating concentrations of [2-O-ethyltyrosine]-oxytocin, inactive per se, potentiate theophylline-disclosing a "threshold phenomenon" for the mediation of neurohypophyseal hormone action. It is concluded that neurohypophyseal peptides are capable of producing graded effects on adenyl cyclase both below and above the range of enzyme activity which evokes graded changes in membrane permeability.
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PMID:Threshold and receptor reserve in the action of neurohypophyseal peptides. A study of synergists and antagonists of the hydroosmotic response of the toad urinary bladder. 543 69

This in vitro study examines the possibility that the E prostaglandins (PGEs) supplement the action of syntocinon on human muscle strips. 11 strips of upper segment myometrium removed from 10 pregnant patients (17-40 weeks gestation) for various reasons were analyzed. The human myometrium at term responded to a minimum concentration of 0.01-0.05 mcg syntocinon and 1-5 ng PGE1 or PGE2 in the 5 ml bath, while the midtrimester myometrium responded to 0.2-1 mcg syntocinon and 2-20 ng PGE1 or PGE2. These results show a 20 times increase in myometrial sensitivity to syntocinon and a 2-4 fold increase in sensitively to PGE1 or PGE2 at term as compared to the midtrimester. A syntocinon dose given immediately following a dose of PGE exhibited a response greater than that elicited by the same dose of syntocinon prior to the PG; this sensitizing effect of PG was observed in both term and midtrimester myometrium. The enhancement effect was observed in the increased duration of syntocinon response or as an increase in amplitude of response or a combination of these, the effect lasting for as long as 90 minutes after the PGE dose had been washed out of the bath. These findings led to the hypothesis that during the parturition process, endogenous PGs act as mediators which sensitize the uterine muscle to circulating oxytocin. The physiological implication of this enhancement effect is that undesirable side effects (vomiting, diarrhea) associated with PG infusion may be reduced or even eliminated when the PG-syntocinon method is used.
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PMID:Interaction of E prostaglandins and syntocinon on the pregnant human myometrium. 555 14

In the present work an attempt is made to get a deeper insight into the mechanism of labor and the events leading to the onset of labor by means of radioimmunological measurements of OT, PGE, PGF, PGEM and PGFM and by determining the oxytocin sensitivity and the concentration of oxytocin receptors. Prostaglandins play a major role for the mechanism of labor in labor of spontaneous onset as well as in several forms of induced labor (intravenous infusion of OT, amniotomy, local application of PGE2). The reason for this seems to be the 3 fold action of prostaglandins: stimulation of myometrial contractions, cervical softening, induction of gap junctions. Moreover prostaglandins produced in the placenta play a major role in the mechanism of placental separation and expulsion. Oxytocin seems to be of importance for the initiation of labor and the final expulsion of the fetus. Immediately before the onset of regular contractions a marked increase of oxytocin sensitivity can be demonstrated which correlates very well with an increase of oxytocin receptor concentration in the myometrium and decidua. Due to this increase in oxytocin sensitivity no rise in oxytocin plasma levels is necessary to induce labor. Apart from the induction of myometrial contractions oxytocin leads via receptors in the decidua to a stimulation of prostaglandin synthesis which can also be demonstrated in vitro. In cases of premature contractions the same mechanisms seem to be operational as at term, oxytocin and prostaglandins again playing a major role. Inhibition of contractions with ethanol is based on the capacity of alcohol to inhibit oxytocin secretion. The contractions inhibiting effect of ritodrine is mediated through the cAMP induced relaxation of the myometrium although possibly a direct reduction of prostaglandin synthesis by ritodrine is possible. Increasing estrogen and decreasing progesterone activities at term lead to multiple subtile changes leading to an increased prostaglandin synthesis and mainly to a rise in oxytocin receptor concentration in the myometrium and the decidua. Oxytocin from the fetal and maternal side stimulates contractions in the myometrium and prostaglandin synthesis in the decidua leading to the onset of labor. With progressing cervical dilatation prostaglandin synthesis is further stimulated; these prostaglandins together with the increased oxytocin plasma levels in the second stage of labor lead to expulsion of the fetus. After delivery prostaglandin synthesis in the placenta leads to placental separation and expulsion.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[The importance of oxytocin and prostaglandins to the mechanism of labor in humans]. 609 5

The effects of melatonin on the motility (isometric tension developed and contractile frequency) of uterine horns isolated from ovariectomized rats as well as on the mechanical responsiveness to added oxytocin or prostaglandin F2 alpha (PGF2 alpha) were explored. The pineal indole (10(-6) M or higher) depressed significantly the spontaneous motility of the uterus and reduced the responses evoked by oxytocin but not those evoked by PGF2 alpha. Melatonin was also tested on the prostaglandin (PG) release into the suspending media from either uterine horns from spayed rats or bovine medial basal hypothalamic (MBH) explants. Melatonin (10(-3) M) diminished the output from the uterus or the MBH of both PGE and PGF-"like material". Similarities between the effects of melatonin and indomethacin as well as the possible physiological relevance of the present findings are discussed.
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PMID:Melatonin blocks in vitro generation of prostaglandin by the uterus and hypothalamus. 610 21

Concentrations of plasma prostaglandins E and F and the 15-keto-13,14 dihydrometabolite of PGF2 alpha (PGFM) were determined by radioimmunoassay in 15 women who underwent induction of labor with oxytocin. Plasma PGFM rose significantly during the oxytocin infusion in nine women who went on to deliver vaginally but did not change in six women in whom induction of labor failed. Plasma PGE and PGF levels also rose during the infusion in the nine women with successful induction of labor but the changes were not statistically significant. In comparison to the six women in whom induction failed, however, plasma PGE in the nine women with successful induction reached significantly higher levels. Oxytocin infusions elicited uterine contractions of similar frequency in both groups of women, but the cervix failed to dilate in the six women in whom induction failed. The oxytocin-induced rise in plasma PGFM is, therefore, not simply a consequence of uterine contractions. We suggest that oxytocin stimulates PGF production in the pregnant uterus when it is appropriately sensitized to oxytocin, causing a potentiation of the oxytocin-induced contractions which is necessary for the contractions to become efficient in dilating the cervix. We further suggest that the stimulation of PGF production by oxytocin is mediated by oxytocin receptors, probably in the decidua.
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PMID:Oxytocin and the initiation of human parturition. I. Prostaglandin release during induction of labor by oxytocin. 627 93

The concentrations of oxytocin and PGE, PGF, and 13,14-dihydro-15-keto-PGF2 alpha (PGFM) in maternal peripheral plasma were measured in serial samples taken at full cervical dilatation and 5, 30 and 120 minutes postpartum. The prostanoid levels were also measured in serial samples of umbilical cord blood taken from the placental end in 4 instances. At full dilatation, plasma PGFM, but not PGE and PGF, was significantly raised over control (no labor) values. Just before or at the time of placental separation (5 minutes postpartum), the concentrations of PGF and PGFM were maximal, about twice the level at full dilatation. The level then decreased but at a slower rate than the metabolic clearance rates, indicating that considerable PGF production occurs in decidua and myometrium in the early postpartum period, after fetus, placenta, and the membranes are expelled. The rapid increase in the prostanoid concentrations in the umbilical cord blood draining the placenta after delivery of the infant suggests that the surge of prostaglandins 5 minutes postpartum originates in the placenta, and probably contributes to uterine contraction and placental separation and expulsion. Plasma OT was significantly raised over prelabor values at full cervical dilatation, and during the third stage, but dropped to control levels 30 minutes postpartum. Exogenous oxytocin infusions begun at delivery of the infant caused a marked increase in plasma OT and maintained the PGFM concentrations at a higher level than in the parturients not receiving oxytocin 2 hours postpartum.
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PMID:[Oxytocin- and prostaglandin plasma concentrations before and after spontaneous labor: evidence of involvement of prostaglandins in the mechanism of placental separation]. 661 34

Prostaglandins (PGs) are thought to have an important function in the initiation and/or propagation of parturition. To define the relationship of individual PGs to one another and compare their alterations with gestational age, PGF, PGE, 6-keto-PGF1 alpha (6KF) and thromboxane B2 (TxB2) were measured in uterine and placental tissue and uterine venous plasma of rats at Days 15, 18, 19, 20, and 21 of pregnancy and at delivery (Day 21 1/2). In addition, concomitant measurements of peripheral plasma estradiol (E2), estrone (E1) and progesterone (P) and pituitary oxytocin (OT) content, putative regulators and/or modulators of PG metabolism, were determined. Significant enhancements (P less than 0.05) in uterine 6KF, TxB2, PGF and PGE concentrations (ng/mg DNA) were detected by Day 20 compared to Day 15 of pregnancy and further dramatic increases were found on Day 21 and at delivery. Although uterine 6KF was present in the highest concentrations, PGF showed the greatest increment from Day 15 to delivery. No alterations in uterine venous plasma PGE or PGF concentration were found with gestational age but 6KF and TxB2 showed significant increases at delivery. The placental concentrations of PGs were approximately 1/50 of uterine tissue. Placental PGE and PGF concentrations (ng/mg DNA) increased only slightly at delivery but the augmentation in 6KF and TxB2 levels were of greater magnitude. Significant increases in E2 and E1 with reciprocal decreases in P occurred on Day 21 of pregnancy. In contrast, pituitary OT content showed no alterations at any of the days examined. These results are consonant with the hypothesis that uterine PGs have an important function in parturition and uterine-placental physiology, and suggest that an increasing estrogen/P ratio at the end of pregnancy is related to enhanced uterine PG levels.
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PMID:Alterations in reproductive tissue prostaglandins E and F, 6-keto-prostaglandin F1 alpha and thromboxane B2 with gestational age in the rat. 689 17


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