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

It has been postulated that hormonal signal acts upon decidua and ammion to trigger labor via production of PGs. In our experiment the decidua cells of pregnant rats (day 19) were digested and dispersed to test the effect of oxytocin on intracellular calcium ion concentration [Ca2+]i which was measured with the fluorescent dye fura-2. Addition of oxytocin 0.001-1 mumol.L-1 to the test system resulted in a dose-dependent transient increase in [Ca2+]i which peaked within 15 s and returned to base line in 12 min. Repeated addition of oxytocin 1 mumol.L-1 failed to elicit a repeated response. In the decidua cells of dihydroepiandroterone sulfate-treated pregnant rats, the [Ca2+]i peak provoked by oxytocin was significantly higher than in the controls. These results suggest that oxytocin may activate the inositol-phospholipid-protein kinase C effector system in decidua cells of pregnant rats. Dihydroepiandrosterone sulfate may influence the action.
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PMID:[Oxytocin provoke intracellular calcium ion concentration in dispersed decidua cells of late pregnant rats]. 786 82

It was elected to induce labor in Mrs AB after excluding any evidence of severe preeclampsia. Both the fetus and Mrs AB were evaluated. The history, physical examination, and laboratory results were all within normal limits for Mrs AB. Her fetus was appropriately grown for gestational age with an estimated fetal weight of 3,200 g. There was ample but not excessive amniotic fluid noted clinically and by sonography. An amniocentesis to document fetal lung maturation was not done. Two hours after commencing parenteral magnesium sulfate therapy, an oxytocin induction of labor was begun. Fetal well-being was assessed using continuous external electronic monitoring of the fetal heart rate and uterine contractions. Three hours after the induction was started, the cervix was completely effaced and 3 cm dilated. The fetal head was at O station. At this time, the fetal membranes were ruptured and clear amniotic fluid was noted. An internal uterine pressure catheter was inserted, and a fetal scalp electrode applied. The patient received 75 mg of meperidine and 25 mg of promethazine intramuscularly at this time. Five hours after commencing the induction of labor, both mother and fetus were tolerating the labor well. The cervix was 7 cm dilated, and the fetal head was at +2/+5 station. The oxytocin induction was discontinued and another 75 mg dose of meperidine was administered. Blood pressure readings between 150/100 mm Hg and 140/98 mm Hg were recorded throughout labor. Urine output exceeded 150 mL/h. The patient delivered a 3,070-g male infant approximately 9 hours after the start of the induction.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mild pregnancy-induced hypertension at term. 806 77

Oxytocin(OT) is considered to have several activities besides strongly inducing myometrial contraction by activating phosphatidilinositol-specific phospholipase C(PI-PLC). These include reconstructing the phospholipid constituents of the cell membrane and activating a variety of fatty acid producing systems. On the other hand, pregnancy-related steroid hormones which are produced by the fetus, placenta and mother are considered to be closely involved in the maintenance of pregnancy and the initiation of labor. In the present study with cultured myometrial cells, we examined what effect these steroid hormones might exert on the intramyometrial production of fatty acid by OT. Our results confirmed bi-phasic production of arachidonic acid(AA), linoleic acid(LA), palmitic acid(PA), and stearic acid(SA) by OT. Phase 1 was an increasing but transient phenomenon having its peak at 30 sec. It is considered to be derived from phosphatidylinositol bis-phosphate. Phase 2 was a persistent and increasing phenomenon which was initiated after 120 sec. It is considered to be mediated by Ca-dependent phospholipase. We also studied the effect of steroid hormones on the production of fatty acid. For AA, LA, and PA, we confirmed that dehydroepiandrosterone sulfate(DHAS) shortened the time taken in reaching the peak of Phase 1 to half of that of the control, and progesterone(P) extended the time 2-3 fold. These findings suggest that DHAS, P and F might modify the human myometrial construction mechanism as a factor which regulates the quantity and velocity of fatty acid production.
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PMID:[The effect of oxytocin on production of free fatty acid in primary human uterine myometrial cell culture]. 837 Oct 25

It is considered that steroid hormones, the concentrations of which vary during pregnancy, play an important role in the initiation of delivery. In the present study, we measured intracellular Ca2+ ([Ca2+]i) change following oxytocin stimulation in cultured human myometrial cells with fura-2, a fluorescent Ca2+ indicator. We also studied the effect of the steroid hormones on changes in [Ca2+]i due to oxytocin stimulation. When the [Ca2+]i change due to 10(-6) M oxytocin reached 100%, the addition of 10(-6) M DHAS (dehydroepiandrosterone sulfate) just before the stimulation raised the [Ca2+]i level to 207%, whereas that of 10(-6) M progesterone dropped to 64%. Moreover DHAS accelerated the speed of increase until the maximum response of [Ca2+]i, while progesterone decelerated it. In another study, human myometrial plasma membrane was solubilized in 7.5mM CHAPSO solution and applied to a binding study. Oxytocin receptors of two different molecular weights, namely 350kD(OTR-1) and 39kD(OTR-2), were extracted from solubilized plasma membrane by employing a gel filtration column. Binding assays were performed for OTR-1 and OTR-2 in the presence of DHAS and progesterone (10(-5) M). The results showed that DHAS enhanced the binding affinity of the receptors, whereas progesterone reduced the maximum binding capacity. It is therefore considered that the steroid hormones added just before oxytocin stimulation might act on receptor levels and modify intracellular Ca2+ response over short periods.
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PMID:[Effects of steroid hormones on change in [Ca2+]i following oxytocin stimulation in cultured human myometrial cells, and on myometrial oxytocin receptor]. 839 68

The role of oxytocin and oxytocin receptors in preterm labor is perhaps more prominent than once thought. The blockade of oxytocin and/or oxytocin receptors has both a theoretical and clinical aspect. Initial trials with the oxytocin antagonist atosiban have been encouraging with respect to efficacy and side effect profile. Current trials are examining the efficacy and dosing regimens of atosiban. Additional work must be done with this drug. However, if subsequent data demonstrate that atosiban is as effective as ritodrine in obtaining uterine quiescence, on the basis of its milder side effect profile, it should be seriously considered as a tocolytic of choice for the treatment of preterm labor. Moreover, it may have significant appeal for combination use with other tocolytics, given its alternative mechanism of action to betamimetics and magnesium sulfate.
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PMID:Atosiban. 861 70

Two different forms of oxytocinase (L-cystine aminopeptidase, CAP; EC 3.4.11.3) were purified from the 9000 g and 105000 g precipitate fractions of human placenta homogenate by sequential chromatography on columns of hydroxyapatite, DE-32, nickel ion affinity, and Sephadex G-200. One species (CAP-I) purifed from the mitochondrial/lysosomal fraction migrated on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis with an apparent molecular mass of 61 kDa; the other (CAP-II) from the microsomal fraction was composed of two subunits with molecular masses of 56 and 40 kDa. The molecular masses of CAP-I and CAP-II estimated by gel filtration were 64 and 97 kDa, respectively. The specific activities of the two species for S-benzyl-L-cysteine p-nitroanilide increased by 357- (for CAP-I) and 139-fold (for CAP-II) compared with the starting preparations. The optimal pH values toward the artificial substrate were approx. 7.4-8.0 for CAP-I and 6.8-8.0 for CAP-II. The Km and Vmax values toward oxytocin were 5.6 microM and 23.4 micromol/h/mg protein for CAP-I, and 38 microM and 15.6 micromol/h/mg protein for CAP-II. Both enzymes were inhibited by the metal-chelating agents, EDTA and o-phenanthroline, whereas they were specifically activated by addition of Co2+: CAP-I was more sensitive to these reagents than CAP-II. L-Methionine strongly inhibited CAP-I, while CAP-II activity was only slightly affected. CAP-II was more sensitive to amastatin than CAP-I. Thus, the two enzymes are quite distinct in their molecular nature and biochemical properties. They may play a regulatory role in the metabolism of oxytocin and other biologically active peptides in intact placenta.
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PMID:Two molecular species of oxytocinase (L-cystine aminopeptidase) in human placenta: purification and characterization. 901

Oxygen free radicals have been suggested to play important roles in atherogenesis and other pathological processes in the blood vessel wall. The vascular wall contains large amounts of extracellular superoxide dismutase (EC-SOD), which is produced and secreted to the extracellular space by smooth muscle cells. In this study, we investigated the influence of factors regulating tension and proliferation of vascular smooth muscle cells and of some interstitial matrix components on EC-SOD expression. The expression and secretion of EC-SOD were upregulated by histamine, vasopressin, oxytocin, endothelin-1, angiotensin II, serotonin, heparin, and heparan sulfate and were downregulated by platelet-derived growth factors-AA and -BB, acidic and basic fibroblast growth factors, and epidermal growth factor. The responses were slow and developed over several days. The findings suggest that various physiological and pathological conditions might markedly influence EC-SOD expression, significantly altering the susceptibility of the vascular wall to effects of the superoxide radical.
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PMID:Vasoactive factors and growth factors alter vascular smooth muscle cell EC-SOD expression. 1155 52

[[9-[(9-Fluorenylmethyloxycarbonyl)amino]xanthen-2(or 3)-yl]oxy]alkanoic acid (XAL) handles have been prepared by efficient four-step routes from 2- or 3-hydroxyxanthone and coupled onto a range of amino-functionalized supports. The resultant XAL supports are the starting points for solid-phase peptide synthesis by Fmoc chemistry. Upon completion of chain assembly, C-terminal peptide amides are released in excellent yields and purities by use of low concentrations [1-5% (v/v)] of trifluoroacetic acid (TFA) in dichloromethane, often without a need for added carbocation scavengers. These cleavage conditions allow retention of all or a significant portion of tert-butyl type and related side-chain protecting groups, which subsequently may be removed fully in a solution process carried out at higher acid concentration. XAL supports are particularly useful for the synthesis of acid-sensitive peptides, including tryptophan-containing sequences that are known to be susceptible to yield- and/or purity-reducing alkylation side reactions. The effectiveness of this chemistry was shown with the syntheses of prothrombin (1-9), acyl carrier protein (65-74), Tabanus atratus adipokinetic hormone, fragments of the protein RHK 1, CCK-8 sulfate, and oxytocin. Furthermore, the application of XAL supports for the preparation of fully protected peptide amides has been demonstrated.
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PMID:Preparation and Applications of Xanthenylamide (XAL) Handles for Solid-Phase Synthesis of C-Terminal Peptide Amides under Particularly Mild Conditions(1-3). 1166 74

The hypothalamo-neurohypophysial system synthesizes and releases arginine vasopressin (AVP) and oxytocin (OXT) with physiological stimulation. In the present study, we investigated localization of a chondroitin sulfate proteoglycan (CSPG), phosphacan/RPTPbeta, in the supraoptic nucleus (SON) and paraventricular nucleus (PVN) of adult rats at both the light and electron microscopic levels. Immunohistochemical analyses demonstrated stronger phosphacan/RPTPbeta immunoreactivity within the SON and PVN compared with adjacent hypothalamic areas. Double labeling experiments showed phosphacan/RPTPbeta immunoreactivity constituting punctate networks to surround the somata and dendrites of AVP- and OXT-secreting magnocellular neurons. Electron microscopic examination further revealed strong phosphacan/RPTPbeta immunoreactivity at extracellular membrane surface of some axons, somata, and dendrites of the SON, but not of synaptic junctions. Interestingly, phosphacan/RPTPbeta immunoreactivity was also observed at extracellular surface membrane between astrocytic processes and neurons rather than between magnocellular neurons. The present results indicate the high expression of the CSPG, phosphacan/RPTPbeta at the extracellular space in the hypothalamic AVP- and OXT-secreting magnocellular neurons.
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PMID:Chondroitin sulfate proteoglycan phosphacan/RPTPbeta in the hypothalamic magnocellular nuclei. 1221 6

Because criteria used for the prediction of preterm labor are poorly effective, many patients receive tocolytic therapy in excess during pregnancy. Beta-mimetic agonists are the reference tocolytic drugs in most countries. Their efficacy in prolonging pregnancy compared to a placebo is proven although no benefit in neonatal morbidity or mortality has been demonstrated. Beta-mimetics have many contraindications, and side-effects are frequent. Serious complications such as pulmonary edema and maternal deaths, though rare, have been reported. Recent research has focused on tocolytic drugs with similar efficacy to beta-mimetics but with less side effects. Calcium-channel-blockers and oxytocin antagonists have been compared with beta-agonists in randomized trials. Both have demonstrated similar efficacy in the prolongation of pregnancy for at least 48 hours. Contrary to beta-mimetics, very few interruptions of treatment have been observed with these treatments. Other tocolytic drugs such as cyclooxygenase inhibitors, although effective in prolonging pregnancy, have unacceptable fetal side effects. Progesterone, antispasmodic drugs and magnesium sulfate have been widely used but their efficacy has not been demonstrated. More recent treatments such as NO-donors and cyclooxygenase-II specific antagonists are not sufficiently evaluated. In conclusion, three main classes may be used as first line tocolytic therapy, beta-adrenergic agonists, calcium-channel-blockers, and oxytocin antagonists. The choice among these treatments may be based on contraindications to beta-mimetics, side-effects of the treatment, or even economic reasons.
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PMID:[Which tocolytic drugs in case of preterm labor?]. 1245 31


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