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)

Using three antisera to oxytocin (OT Pitt Ab-1, OT Pitt Ab-2, and TOR OT Ab), we found comparable levels of OT in response to infant suckling and during infusion of synthetic OT, and identical standard curves with biological and synthetic standards of OT. Pitt Ab-1, but not Pitt Ab-2 or TOR OT Ab, measured increased OT in response to estrogen. Using an arginine vasotocin RIA (TOR AVT Ab), we found an increase in AVT immunoreactivity after estrogen treatment. Mean basal OT levels measured with OT Pitt Ab-2 in plasma of men [0.75 +/- 0.06 (+/- SEM) microU/ml] and women (0.8 +/- 0.09 microU/ml) were lower than OT measured with Pitt Ab-1 (1.7 +/- 0.09 microU/ml in men and 1.7 +/- 0.07 microU/al in women; P less than 0.001). Mean OT measured with Pitt Ab-2 in the plasma of women given estrogen chronically (0.8 +/- 0.04 microU/ml) and acutely (0.6 +/- 0.15 microU/ml) were not significantly different from basal levels. OT levels measured with Pitt Ab-1 in the same samples were 4.6 +/- 0.5 and 4.3 +/- 0.5 microU/ml, respectively, both significantly increased from basal levels (P less than 0.001) and significantly higher than OT measured with Pitt Ab-2 (P less than 0.001). Mean OT measured with Pitt Ab-1 in the plasma of pregnant women was 8.6 +/- 1.02 microU/ml, significantly higher than OT measured with Pitt Ab-2 (1.0 +/- 0.3 microU/ml; P less than 0.001). Men given 25 mg diethylstilbestrol had significant increases in OT measured with Pitt Ab-1 and in AVT measured with TOR AVT (P less than 0.01), but not in OT measured with Pitt Ab-2. Plasma from a man given diethylstilbestrol was prepared for high performance liquid chromatography and applied to a C18 muBondapak reverse phase column. The plasma contained two peaks of immunoreactivity detected as OT with Pitt Ab-1 and as AVT using TOR AVT Ab. The material was not detected by Pitt Ab-2 or TOR OT Ab and did not coelute with standards of OT, AVT, or AVP. Pregnancy plasma, thioglycolic acid, chymotrypsin, and trypsin reduced Pitt Ab-1, Pitt Ab-2, and TOR OT immunoreactivity of synthetic OT. The percent recovery of OT immunoreactivity was not significantly different with Pitt Ab-1 vs. Pitt Ab-2. A novel peptide, which is increased in response to administered estrogen, is present in human plasma and is detected by some antisera to OT and AVT. The observation explains the wide variability in OT levels in the estrogen-primed state and provides a new mechanism to study estrogen-related physiology and pathophysiology.
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PMID:A novel oxytocin-like and vasotocin-like peptide in human plasma after administration of estrogen. 396 93

L[35S]Cys-arginine vasopressin, -oxytocin, and -somatostatin were purified from hypothalami and neurohypophyses 4 h after rats received L[35S]Cys via the third ventricle. After acetic acid extraction, Sephadex G-25 filtration, and chemoadsorption to C18-silica (Sep-Pak cartridges), the labeled peptides were rapidly separated by gradient elution, reversed phase, high pressure liquid chromatography (HPLC). The identity and isotopic purity of the labeled peptides were determined by several reversed phase HPLC procedures in conjunction with chemical modification. The labeled peptide fractions were at least 50% radiochemically pure. Using this HPLC isolation procedure, incorporation of L-[35S]Cys into each peptide was determined n hydrated and dehydrated rats. Label incorporation into arginine vasopressin and oxytocin in the hypothalamus and the neurohypophysis of dehydrated rats was 2-3 times greater than that in hydrated rats. Incorporation of label into hypothalamic and neurohypophyseal somatostatin was unaffected by the hydration state of the animal. This procedure thus provides a very rapid, but sensitive, set of techniques for studying the control of small peptide biosynthesis in the brain.
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PMID:In vivo biosynthesis of L-[35S]Cys-arginine vasopressin, -oxytocin, and -somatostatin: rapid estimation using reversed phase high pressure liquid chromatography. 611 94

An improved RIA for measurement of oxytocin in blood is described by using an extraction method with SEP-PAK C18 cartridges, which allows also concentration of the sample, a new antiserum with a higher sensitivity to standard oxytocin and preparation of the standard curve in buffer. The lower limit of assay sensitivity was 0.25 pg/tube, corresponding to 0.25-1.0 pg/ml plasma depending on the amount of plasma extracted. Hence, it was no problem to measure oxytocin basal concentrations in peripheral blood in the range of 0.6-4 pg/ml plasma depending on the stage of the oestrous cycle. The highest oxytocin concentrations occurred during the early and mid-luteal phase. The method has been applied also for samples from women, sheep, pigs and horses. Mean (+/- SD) recovery of oxytocin added to plasma or only buffer after extraction was 71.3 +/- 8.1%, and the coefficient of variation (CV) = 11.4% (n = 27 assays). The intra-assay CV of two control samples was 7.9 +/- 2.8 and 7.8 +/- 2.4% (n = 17 assays). The inter-assay CV of 5 control samples with low and high oxytocin concentrations varied between 10.8 +/- 17.3% (n = 25 assays). The 50% intercept was 2.5 +/- 0.3 pg, CV = 11.3% (n = 29 assays).
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PMID:Oxytocin determination by radioimmunoassay. III. Improvement to subpicogram sensitivity and application to blood levels in cyclic cattle. 668 55

The existence of a functional paracrine loop between oxytocin and prostaglandin F2-alpha in human placental cells has been demonstrated. The present study was undertaken to investigate further the possible interrelationships between oxytocin and eicosanoids in human intrauterine tissues at term gestation. Therefore, we evaluated the effect of leukotriene B4 (LTB4) on oxytocin (OT) production by explants of fetal membranes and amnion and the effect of oxytocin on the production of LTB4 and prostaglandin E2 (PGE2) by both fetal membranes and amnion. In all cases studied (n = 25), short-term cultures of tissue explants (fetal membranes or amnion) have been carried out. The production of eicosanoids and oxytocin in culture medium was evaluated. Oxytocin measurement was carried out by radioimmunoassay following extraction of the substance with Sep Pak C18 cartridges, PGE2 and LTB4 were measured by radioimmunoassay directly in culture medium. Results show that LTB4 has no significant stimulatory effect on oxytocin production by fetal membranes or amnion tissue. On the other hand, oxytocin stimulates PGE2 release by both fetal membranes and isolated amnion, but has no effect on LTB4 production by these tissues. Taken together, these findings suggest the following conclusions: (1) a paracrine loop between LTB4 and oxytocin is lacking in fetal membranes and amnion at term pregnancy; (2) oxytocin exerts a stimulatory effect on PGE2 release by both fetal membranes and amnion; (3) the interrelationships between oxytocin and the different eicosanoids in the above tissues seem to be highly selective.
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PMID:Interrelationships between oxytocin and eicosanoids in human fetal membranes at term gestation: which role for leukotriene B4? 961 Apr 26

A method for labeling proteins and peptides with (methoxycarbonyl cyclopentadienyl)tricarbonyl rhenium and technetium is described. The precursors used for this labeling are conveniently produced from perrhenate and pertechnetate, respectively, using a double ligand transfer reaction. For labeling the lysine residues of the model protein bovine serum albumin, the technetium methyl ester was saponified and then transformed into its N-hydroxysuccinimidyl ester. For the labeling of the model peptides leucine enkephalin, substance P, oxytocin, and the tumor imaging/therapy candidate octreotide, the rhenium methyl ester was saponified and activated using either 1-hydoxybenzotriazole or 1-hydroxy-7-azabenzotriazole. The activation and peptide-coupling reactions were followed using reversed-phase (C18) HPLC and yields averaged approximately 70%.
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PMID:Protein and peptide labeling with (cyclopentadienyl)tricarbonyl rhenium and technetium. 981 71

The retention behaviour and selectivity of selected basic, neutral and acidic peptides have been studied by capillary electroendoosmotic chromatography (CEC) with Hypersil C8, C18, Hypersil mixed-mode, and Spherisorb C18/SCX columns, 250 (335) mm x 100 microns, packed with 3 microns particles, and eluted with mobile phases composed of acetonitrile-triethylamine-phosphoric acid (TEAP) at pH 3.0 using a Hewlett-Packard Model HP3DCE capillary electrophoresis system. The selected peptides were desmopressin (D), two analogues (A and B) of desmopressin, oxytocin (O) and carbetocin (C). The peptides eluted either before or after the electroendoosmotic flow (EOF) marker, depending on the concentration of acetonitrile used and the buffer ionic strength. The retention and selectivity of these peptides under CEC conditions were compared to their behaviour in free zone capillary electrophoresis (CZE), where the separation mode was based on the electrophoretic migration of the analytes due to their charge and Stokes radius properties. In addition, their retention behaviour in RP-HPLC was also examined. As a result, it can be concluded that the elution process of this group of synthetic peptides in CEC with a TEAP buffer at pH 3.0 is mediated by a combination of both electrophoretic migration processes and retention mechanisms involving hydrophobic as well as silanophilic interactions. This CEC method when operated with these 3 microns reversed-phase and mixed-mode sorbents with peptides is thus a hybrid of two well-known analytical methods, namely CZE and RP-HPLC. However, the retention behaviour and selectivity of the selected peptides differs significantly in the CEC mode compared to the RP-HPLC or CZE modes. Therefore this CEC method with these peptides represents an orthogonal analytical separation procedure that is complimentary to both of these alternative techniques.
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PMID:Separation of selected peptides by capillary electroendoosmotic chromatography using 3 microns reversed-phase bonded silica and mixed-mode phases. 1048 34

The successful coupling of capillary electrochromatography (CEC) to an ion trap mass spectrometer via a nanoelectrospray interface (nESI) is described. Using a conductively coated tip butted to the end of a CEC column, it was possible to obtain a stable spray without any sheath liquid being employed. Selected small peptides were separated with CEC columns (100 microm i.d./25 cm long) packed with 3 microm Hypersil C8 or C18 bonded silica particles with an eluent composed of ammonium acetate/acetonitrile. Peptide mixtures of desmopressin, peptide A, oxytocin, carbetocin and [Met(5)]-enkephalin were detected in the mid-attomole range, which is the lowest amount analyzed using CEC combined with MS detection. It was also observed that sensitivity can be compromised at higher separation voltages. We demonstrate that CEC/nESI-MS, at the current stage of development, represents one of the most sensitive systems for peptide analysis.
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PMID:Capillary electrochromatography/nanoelectrospray mass spectrometry for attomole characterization of peptides. 1093 36

Vasopressin, oxytocin as well as other active nonapeptides (vasotocin, etc) are difficult to isolate from tissues. Traditionally they were identified using cumbersome biological assays or immunoassays, commercially unavailable, and with some cross reactivity. Based on the fact that all these peptides have two Cysteines in their molecules we developed a simple, sensitive and specific method to detect them by HPLC after pre-column fluorescent derivatization with monobromobimane (mBBr). The peptides were separated on a Vydac C18 column after reduction with Tris (2-carboxyethyl) phosphine (TCEP) and derivatization with mBBr for 5 minutes in dark. Using this method we were able to detect specific peaks for arginine-, lysine-vasopressin, and vasotocin at levels as low as 10 pmol. The method can be used to detect other active peptides with cyst(e)ins in their molecule, as well.
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PMID:A chemical method to isolate hypothalamic nonapeptides by coupling cyst(e)in with bimane. 1206 2

Effects of a dietary lipid supplement containing calcium salts of fatty acids and methionine hydroxy analogue on plasma prostaglandin F2alpha (PGF2alpha) metabolite (PGFM) and milk fatty acid profiles were examined in 40 late lactation, nonpregnant, Holstein-Friesian cows for a period of 70 days. Effects on milk production, milk composition, and blood metabolites were also examined. Cows were paired on the basis of lactation number (first lactation, n = 8; second lactation, n = 32) and randomly assigned from within pairs to one of two dietary treatments: unsupplemented control (C) or 400 g per cow per day of the lipid supplement (S). Cows receiving the supplement had higher (P < 0.05) total milk production, total fat production (kg), and total lactose production (kg). Plasma cholesterol was significantly higher (P < 0.01) after 30 days of treatment in cows receiving the supplement. Cows receiving the supplement had lower (P < 0.01) concentrations of short chain milk fatty acids (C4:0 to C14:1) and higher concentrations of long chain fatty acids (C18:1 and C18:2; P < 0.01) than control animals. Oxytocin-induced prostaglandin release on Day 16 postovulation was increased (P < 0.01) in cows receiving the supplement. In conclusion, supplementation with calcium salts of fatty acids and methionine hydroxy analogue significantly increased milk yield and plasma PGFM.
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PMID:Effects of calcium salts of fatty acids and calcium salt of methionine hydroxy analogue on plasma prostaglandin F2alpha metabolite and milk fatty acid profiles in late lactation Holstein-Friesian cows. 1237 18

The objective of the experiment was to determine the effects of fat supplementation on cyclicity, progesterone concentration, follicular development, conception rate, embryo mortality, and plasma concentrations of prostalglandin F metabolite (PGFM) in cattle. The hypothesis of this experiment was that feeding flaxseed, which is a source rich in C18:3, would increase conception rate of dairy cows due to decreased plasma PGFM concentrations. A total of 138 lactating Holstein cows were allotted at calving to three groups of 46 cows, blocked for similar calving dates. Cows within each block were assigned to one of three isonitrogenous, isoenergetic, and isolipidic supplements based on either whole flaxseed (FLA), Megalac (MEG) or micronized soybeans (SOY). The diets were fed from calving to Day 50 of pregnancy for pregnant cows, or 120 day postpartum for those not diagnosed pregnant after AI. Detailed measurements of PGFM and follicle dynamics were only made on four cows for FLA and five cows for both MEG and SOY. The response in PGFM concentration following the oxytocin challenge administered around Week 11 of lactation was similar over time among treatments. Plasma progesterone concentrations from Days 17 to 21 of the estrous cycle starting around Week 9 of lactation and determined on a subsample of cows (n=for FLA and n=5 for both MEG and SOY) were higher for cows fed FLA than for those fed SOY (P=0.04) or MEG (P=0.06). Conception rates were similar among treatments. Total embryo mortality was lower (P=0.07) for cows fed FLA (0%) compared to those fed either MEG (15.4%) or SOY (8.0%). The mean size of the CL measured during a complete estrous cycle from Week 9 of lactation was smaller for cows fed SOY (16.3 mm) compared to those fed either FLA (19.1 mm) or MEG (18.3 mm). We inferred that pregnancy losses could be reduced by feeding whole flaxseed as a result of its effects on different factors such as modulation in concentration of progesterone and size of the CL.
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PMID:Conception rate and reproductive function of dairy cows fed different fat sources. 1673 61


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