Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxytocin (OT) and the oxytocin-neurophysin (OT-Np) were measured by RIA in samples of cerebrospinal fluid (CSF) obtained sequentially at 0600, 1200, 1800, and 2400 h from six patients in whom intrathecal catheters were temporarily placed for CSF rhinorrhea. The highest levels of OT in CSF were found at 1200 h. An analysis of variance of sequential measures of the concentration of OT in samples of CSF obtained every 6 h over a 30-h period showed the mean levels (+/- SEM) of OT at 1200 h, 6.41 +/- 1.13 microU/ml and 5.06 +/- 0.58 microU/ml, to be significantly higher (p less than 0.05) than mean levels of OT at 0600 h, 2.50 +/- 0.65 microU/ml; 1800 h, 2.63 +/- 0.61 microU/ml and 2.64 +/- 1.21 microU/ml; and 2400 h, 2.86 +/- 1.13 microU/ml. The levels of OT-Np in CSF did not show a similar peak. In three of the patients simultaneous samples of blood were obtained for measurement of the same peptides, but no corresponding peak of OT or its Np was found in plasma of these three patients. The level of OT in CSF at all times was also significantly higher (p less than 0.05) than the level of OT in plasma of these three patients. Levels of OT and OT-Np were measured by RIA of samples of plasma obtained hourly for a 24-h period from six healthy men and six healthy women. No diurnal variation of OT or its Np in the plasma of men or women was found. This pattern of OT in the CSF of humans is similar to the pattern of OT in the CSF of the Rhesus monkey, but in contrast to the lack of a clearly defined peak of OT in the CSF of the cat or the rat. These observations in humans reinforce the differences among species of the secretion of OT in the CSF.
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PMID:A time-dependent peak of oxytocin exists in cerebrospinal fluid but not in plasma of humans. 661 69

Plasma levels of oxytocin and prolactin were measured before and during 12 minutes of breast pump stimulation in five healthy, lactating, amenorrheic women on three occasions: ten to 90 days post partum, 90 to 180 days post partum, and 180 days to one year post partum. Baseline mean (+/- SEM) plasma oxytocin levels were similar in the three study periods. Mean stimulated plasma oxytocin levels increased in the three study periods (each P less than .001; mean baseline versus stimulated). Stimulated plasma oxytocin values were significantly greater at ten to 90 than at 90 to 180 days (P less than .05; analysis of variance). Baseline serum prolactin levels were 61 +/- 9.5, 36 +/- 8.6, and 33 +/- 10.8 ng/ml, respectively (not significant; one-way analysis of variance). Mean stimulated prolactin levels were 71 +/- 8.1, 43 +/- 4.5, and 43 +/- 2.8 ng/ml, respectively (not significant). Thus, the oxytocin secretory reflex continues in long-term lactation for the first year post partum. In addition, breast stimulation in long-term lactating women continues to produce a slight increase in serum prolactin levels.
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PMID:Oxytocin and prolactin responses in long-term breast-feeding. 668 41

Oxytocin (OT) was measured by RIA in plasma of women during hypocontractile labor before and during graded doses of iv infused synthetic OT. Based upon in vitro studies of recovery of OT from pregnancy plasma, blood was collected into heparinized tubes which were kept at 4 C. The addition of EDTA and phenanthrolene to an aliquot of each sample resulted in measured levels of OT in plasma that correlated closely with levels measured in the absence of these reagents (r2 = 0.86). Comparison of OT levels in plasma of normal individuals determined in the presence and absence of these reagents also yielded a high degree of linear correlation (r2 = 0.97). The mean level of OT in 11 women during hypocontractile labor before the infusion of OT was 1.01 +/- 0.31 (+/- SEM) microU/ml. There was a linear correlation between the dose of OT infused and the level of OT in plasma with infused doses of OT between 1 and 4 mU/min (r2 = 0.99). The time of onset of adequate uterine contractility was recorded by on-line computer analysis, and the level of OT in plasma obtained simultaneously was variable among the women. The mean OT MCR in these women was 17.4 +/- 9.2 (+/- SEM) ml/kg X min, similar to the MCR in normal men (17.6 +/- 2.1 ml/kg X min). Levels and pharmacokinetics of OT during hypocontractile labor were similar to those in nonpregnant individuals and women in late pregnancy. The variability in OT concentrations at the time of adequate uterine contractility suggests that individual myometrial sensitivity is an important determinant of the response to administered OT in humans.
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PMID:Studies of oxytocin in plasma of women during hypocontractile labor. 669 37

Hypophysial portal blood was collected from pentobarbital-anesthetized male rats, and the content of oxytocin (OT) was measured by RIA. The concentration of OT in portal plasma was 1.88 +/- 0.48 ng/ml (SEM) and was at least 15 times higher than the concentration of OT in peripheral plasma samples from the same rats. Dilutions of portal plasma produced a displacement curve parallel to those of synthetic OT and posterior lobe extract. The data support a possible role for OT as a hypothalamic-releasing hormone.
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PMID:High concentrations of oxytocin in hypophysial portal plasma. 670 37

To determine if oxytocin (OT) is present in cynomolgus monkey corpus luteum, OT was measured by a specific and sensitive RIA in 13 corpora lutea, ovarian venous plasma on the ipsilateral side and peripheral venous plasma at different stages of the luteal phase. Serial dilution of acetic acid extract of the corpus luteum showed parallelism with standard OT in the RIA. Total content of OT in corpus luteum was 1.9 +/- 0.5 ng (mean +/- SEM) with a content of 0.4-0.8 ng in early luteal phase, 1.0-6.2 ng in midluteal phase, and 0.4-0.7 ng in late luteal phase. OT concentrations in corpus luteum were 21.0-75.2 ng/g wet wt in early luteal phase, increasing to 34.4-602.5 ng/g in midluteal phase; and declining to 3.4-117.4 ng/g in late luteal phase. OT concentrations per mg protein in the corpus luteum were 0.05-19.6 ng with peak concentrations of 14.7-19.6 ng/mg protein on day 22. Sephadex G-25 column chromatography of the corpus luteum extract revealed a single peak for binding activity similar to that of synthetic OT on the RIA. Ovarian vein blood from the same side as the corpus luteum had a significantly higher OT concentrations of 161.2 +/- 29.7 pg/ml on days 15-24 than 16.8 +/- 3.6 pg/ml on days 25-28 (P less than 0.01) and peripheral plasma OT levels of 23.2 +/- 3.4 pg/ml (P less than 0.025). Our findings indicate that OT is present and probably produced by monkey corpus luteum with peak OT concentrations found in midluteal phase. Thus OT may play a role in primate corpus luteum function.
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PMID:Oxytocin in the corpus luteum of the cynomolgus monkey (Macaca fascicularis). 674 70

RIA for the measurement of oxytocin in human plasma is described. Extraction of oxytocin from larger peptides in plasma used acetone precipitation with a 75% +or- 2 SEM recovery of oxytocin. Nonspecific binding of the assay was less than 4% and the minimum level of detection was 0.2 mcU/tube. No cross-reactivity was noted with neurophysins, arginine, or lysine vasopressin. The mean basal level (+or- SEM) of oxytocin in men was 1.80 +or- 0.07 mcU/ml and was not different in normal women (1.71 +or- 0.07 mcU/ml). Changes in posture had no effect on the levels of oxytocin. Samples obtained every 15 minutes over 4 hours showed no pulsatile secretion of oxytocin. In women chronically receiving estrogen as an oral contraceptive, oxytocin was greater than normal (4.59 +or- 0.51 mcU/ml; P0.01). Estrogen-stimulated neurophysin was also elevated *8.45 +or- 1.99 ng/ml; P0.005). Acute ingestion of estrogen caused an increase in the level of oxytocin in plasma by 12 hours and a concomitant elevation of estrogen-stimulated neurophysin. When the neurophysin was isolated from plasma obtained from a subject after ingestion of estrogen, the neurophysin from plasma comigrated on a polyacrylamide gel with a human pituitary standard of estrogen-stimulated neurophsin. In the studies in which neurophysin was elevated, the correlation between the level of oxytocin and the level of estrogen-stimulated neurophysin in plasma was significant (P0.01). The observation that estrogen administration stimulates the release of oxytocin and estrogen-stimulated neurophysin provides additional evidence that this neurophysin is the oxytocin-neurophysin of man.
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PMID:Oxytocin in human plasma: correlation with neurophysin and stimulation with estrogen. 722 98

The effect of nursing on plasma levels of oxytocin (OT), arginine vasopressin (AVP), and PRL was studied in six normal women 2-3 days post partum. Maternal blood samples were obtained for measurement of OT, AVP, PRL, sodium, and osmolality 3 and 0 min before suckling, at 3-min intervals for 15 min during suckling, and 5 min after completion of suckling. Plasma OT rose during suckling from a mean (+/- SEM) baseline value of 1.1 +/- 0.2 to 3.6 +/- 0.6 microU/ml by 3 min (P < 0.001), reached a peak level of 6.4 +/- 1.5 microU/ml by 6 min (P < 0.005), and remained elevated for the entire 15-min period of suckling. Serial measurements of plasma OT during suckling failed to show a pattern consistent with episodic secretion. The baseline plasma AVP concentration was 0.4 +/- 0.1 microU/ml and was not significantly altered by suckling. Plasma sodium and osmolality remained unchanged during the suckling period. The baseline serum PRL level was 268 +/- 24 ng/ml and rose to 362 +/- 31 ng/ml after 15 min of suckling (P < 0.05). The data suggest that suckling is a specific stimulus for OT and PRL secretion but has no effect on AVP release.
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PMID:The effect of nursing on neurohypophyseal hormone and prolactin secretion in human subjects. 741 69

Two neurophysins (NPs) that are thought to be the primary protein forms produced with the hormones vasopressin (VP) and oxytocin (OT) were isolated from 5000 human pituitary glands. In sucrose gradient centrifugation of human neural lobes, each of these NPs had a distribution similar to that of either VP or OT. Such differential localization of 1 human NP (HNP) with VP and the other HNP with OT suggests an association of their biosynthesis, and it is on the basis of this association that 1 NP has been named VP-associated HNP (VP-HNP) and the other OT-associated HNP (OT-HNP). The purified proteins were complexed to bovine thyroglobulin in order to develop specific antisera. RIAs developed with these antisera are effective for each HNP in the range of 5-320 pg. Reference standards in both assays were corrected for protein content using amino acid analysis to obtain absolute protein concentration; this type of correction is recommended for all RIAs that measure proteins. The RIAs were used to measure the concentrations of HNPs in unextracted human plasma. In healthy, sitting, normally hydrated subjects of both sexes, VP-HNP and OT-HNP were, respectively, 73 +/- 5 and 382 +/- 30 pg/ml (mean +/- SEM; n = 20); there was no significant difference between values in males and females, provided the latter were not taking medication. Women on oral contraceptives had elevated (> 3 times normal) levels of OT-HNP but normal levels of VP-HNP. Eleven patients who had the syndrome of inappropriate secretion of antidiuretic hormone had elevated levels of VP-HNP but not necessarily of OT-HNP. Surgery was found to consistently increase plasma VP-HNP but not OT-HNP. In two of six subjects smoking caused a dramatic release of VP-HNP, as indexed by plasma levels which rose to more than 50 times the control values. One patient with lithium-induced nephrogenic diabetes insipidus had elevated plasma concentrations of both NPs. The sensitivity and specificity of the RIAs may make them useful clinically in certain pathological states.
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PMID:Isolation and partial characterization of two human neurophysins: their use in the development of specific radioimmunoassays. 741 70

Oxytocin (OT) metabolic clearance rates (MCR) were measured during the constant infusion of 4 mU/min synthetic oxytocin (Pitocin) in 22 healthy adult subjects: 6 men, 6 nonpregnant women, and 10 pregnant women. Pregnant subjects were at term and undergoing OT induction of labor. Mean (+/- SEM) baseline plasma OT concentrations were similar for men, pregnant women, and nonpregnant women. OT MCR was 27 +/- 1.8 ml/kg/min in men; 20.6 +/- 2.8 ml/kf/min in nonpregnant women; and 23.1 +/- 2.6 ml/kg/min in pregnant women. These values were statistically similar. The OT MCR corrected to prepregnancy weight was 25.4 +/- 2.0 ml/kg/min. This value is also statistically similar to the values in men and nonpregnant women. OT degradation was studied in vitro in pooled plasma of men, nonpregnant women, pregnant women, and cord blood. No significant degradation was observed in men, nonpregnant women, or cord plasma. There was an 85% per hour decrease in OT concentration in plasma of pregnant women, confirming earlier reports. These results suggest that the cystine amino peptidase enzyme mediating OT degradation in pregnancy plasma is preferentially secreted by trophoblast cells into maternal plasma and does not seem to cross the placental barrier.
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PMID:Pharmacokinetics of oxytocin in the human subject. 744 13

This investigation was conducted to evaluate the potential capacity of the human fetal membranes-decidua parietalis, and in particular the chorion laeve, to degrade uterotonins that are produced in amnion, are present in amniotic fluid, or both. The four uterotonins that have been evaluated most frequently as myometrial contractants potentially involved in the initiation of human parturition are prostaglandins, oxytocin, endothelin-1, and platelet-activating factor. We assessed the levels of mRNA and the specific activities (SAs) of enkephalinase (the plasma membrane endopeptidase that degrades endothelins) and prostaglandin dehydrogenase (PGDH) in human fetal membranes, i.e. amnion and chorion leave, and in decidua parietalis. The SA of oxytocinase (which inactivates oxytocin) in these tissues also was determined. The SA of enkephalinase in chorion laeve from all anatomical sites (singleton and diamnionic-dichorionic twin placentae) in all pregnancies studied (mean +/- SEM, 95 +/- 7.9 ng/min.mg protein; n = 28) is similar to that in human fetal kidney (89.5 +/- 2.8; n = 6). Kidney tissue is believed to be one of the richest sources of enkephalinase. The SAs of enkephalinase in amnion (18.3 +/- 2.3 nmol/min.mg protein; n = 29) and in decidua parietalis (31.8 +/- 6.7; n = 20) also were high, but significantly less than that in chorion leave. The level of enkephalinase mRNA in chorion laeve in singleton pregnancies is high, as is the SA of enkephalinase (111.9 +/- 10.6 nmol/min.mg protein; n = 17). In paired chorion laeve tissues from five diamnionic-dichorionic twin placentae, the SAs of enkephalinase in reflected chorion laeve (74 +/- 12.8; P < 0.06 compared with singletons) and fused chorion laeve (64.8 +/- 6.5; P < 0.001 compared with singletons) were similar. The SA of PGDH in reflected chorion leave (46.3 +/- 6.9 nmol/min.mg protein; n = 19) was significantly greater than that in decidua (16 +/- 5.5; n = 15). There was a significant correlation between the levels of PGDH mRNA and PGDH enzyme SA. In fused chorion laeve of diamnionic-dichorionic twin placentae, the SA of PGDH (14.9 +/- 7.3; n = 4) was much less than that in reflected chorion laeve of the same twin pregnancy (70.5 +/- 14.7; n = 4). PGDH mRNA was not detectable in amnion tissue (n = 5) by northern analysis, and the SA of PGDH (< 1.2 +/- 1.0; n = 6) in amnion was undetectable or near the lower limit of assay detection.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Human fetal membrane contribution to the prevention of parturition: uterotonin degradation. 810 36


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