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)

In the present study, a radioimmunoassay for oxytocin determinations is presented. In addition, we investigated whether the elevation of insulin, VIP and gastrin levels demonstrated to occur in response to suckling in lactating dogs may be induced by released oxytocin. Therefore, oxytocin was infused i.v. into conscious dogs in amounts calculated to give rise to plasma levels observed during physiological circumstances. Plasma levels of oxytocin, insulin, VIP (vasoactive intestinal polypeptide) and gastrin were measured by radioimmunoassay. When oxytocin was infused at a rate of 0.22 and 2.2 nmol kg-1 h-1, plasma oxytocin levels rose to 176 +/- 25 fmol ml-1 and to 1490 +/- 400 fmol ml-1, respectively, 10 min after the infusions were started. Plasma insulin levels rose in response to oxytocin administered at a rate of 0.22 and 2.2 nmol kg-1 h-1. A peak was recorded within 5 min of oxytocin infusion, that is, before maximal oxytocin levels were recorded, and basal levels were reached within about 20 min. The VIP levels rose slightly following infusion of oxytocin at 0.22 nmol kg-1 h-1, but a clear-cut response that lasted for 60 min was observed following infusion of oxytocin at the highest dose. In contrast, gastrin levels were not influenced by the oxytocin infusions. Suckling in dogs is followed by rapidly occurring short-lasting elevations of oxytocin levels in plasma which amount to 50-100 fmol ml-1. Since insulin and VIP were released by oxytocin when administered in amounts that give rise to plasma levels close to those levels, it is suggested that the secretion of insulin and VIP that occurs in response to suckling in lactating dogs may in part be caused by previously released oxytocin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Oxytocin infusions increase plasma levels of insulin and VIP but not of gastrin in conscious dogs. 390 74

1. The interaction between lipid monolayers spread on the surface of water and oxytocin, [8-arginine]-vasotocin and [1-asparagine-5-valine]-angiotensin II in the subphase was investigated in a Langmuir surface trough by studying the changes in pressure produced on injection of various quantities of the polypeptide solution under the film. 2. The effect of 2m- and 4m-urea on the character of the adsorption is reported. 3. Structures for the adsorbed films formed in this way are suggested. 4. If the lipid monolayer is taken as a suitable model of cell membranes, then it may be supposed that the effect of such structures forming in cell membranes would be to provide effective ;pores' to facilitate the movement of water and other small molecules across the membrane.
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PMID:Interaction of polypeptide hormones with lipid monolayers. 429 25

1. Metals potentiate the contractile effects of S-S polypeptides in depolarized rat uterus. Their order of potency is Co(++)>/=Co(+++)>/=Mn(++)>/=Ni(++)>/= Mn(+++)>Zn(++)>/=Mg(++)>Fe(++)>Fe(+++)>/= Ca(++)>Be(++)=Sr(++)=Ba(++)=Cu(++)=O.2. S-S polypeptides with relatively weak oxytocic activity such as lys-vasopressin, arg-vasopressin and orn-vasopressin are strongly potentiated by metals while highly active polypeptides such as oxytocin are weakly potentiated.3. Potentiation by metals was specific for S-S polypeptides; other polypeptides (bradykinin, hypertensin) as well as acetylcholine and isoprenaline were unaffected.4. Potentiation by metals occurs rapidly and is fully reversible. In all cases some activity was retained by S-S polypeptides even in the complete absence of metals.5. A scheme which could account for the observed effects has been formulated. This assumes the formation of a ternary complex between receptor, metal and polypeptide leading to improved alignment between polypeptide and receptor.6. Analogies are discussed between metal enzymes and the S-S polypeptide receptor for which the term metal receptor is proposed.
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PMID:The effect of metals on the S-S polypeptide receptor in depolarized rat uterus. 430 88

1. The responses of the smooth muscle of the capsule and blood vessels of the isolated, perfused human spleen to sympathetic nerve stimulation, adrenaline, noradrenaline, angiotensin, oxytocin, vasopressin, isoprenaline and acetylcholine have been investigated and compared with those of dog spleen.2. Stimulation of the postganglionic sympathetic nerves to the human spleen at frequencies of 3-10 Hz evoked graded vasoconstriction but very small changes in spleen volume.3. The injection of adrenaline and noradrenaline in doses of 0.25-25 mug to the human spleen produced graded increases in splenic vascular resistance with very small decreases in spleen volume.4. Administration of the alpha-adrenoceptor blocking drug phenoxybenzamine completely abolished or considerably reduced the vascular responses of the human spleen to sympathetic nerve stimulation or the injection of noradrenaline.5. The vascular action of adrenaline was often reversed to elicit a vasodilatation after phenoxybenzamine suggesting the presence of beta-adrenoceptors in the vascular bed. This was confirmed by the administration of isoprenaline which induced a marked reduction in vascular resistance of the human spleen.6. The polypeptides angiotensin and vasopressin induced a marked vasoconstriction in the human spleen without changes in the spleen volume. These effects were uninfluenced by the administration of phenoxybenzamine.7. The polypeptide oxytocin caused a slight vasodilatation in the human spleen, an effect almost exactly mimicked by the preservative chlorobutanol.8. Preliminary experiments suggest that noradrenaline is the transmitter released by the postganglionic nerves to the human spleen.9. These results provide direct evidence that the normal human spleen, unlike that of the dog, does not have a reservoir function. It is suggested that contractions of the enlarged human spleen may occur in various pathological conditions.
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PMID:Responses of the isolated, perfused human spleen to sympathetic nerve stimulation, catecholamines and polypeptides. 433 51

1. Three neurophysins, proteins that bind the polypeptide hormones oxytocin and vasopressin, have been isolated from acetone-dried porcine posterior pituitary lobes. The proteins have been named porcine neurophysins-I, -II and -III in order of their electrophoretic mobilities at pH8.1. 2. Electrophoretic comparison of the purified proteins, which are homogeneous on starch-gel electrophoresis, with the soluble proteins of fresh porcine posterior pituitary lobes extracted in 0.1m-HCl and in buffer pH8.1 suggests that the isolated proteins are native to the fresh tissue. 3. Neurophysins-I and -II are present in similar amounts in the tissue, whereas neurophysin-III is present only in small quantities. Acetone-dried tissue also contains traces of other hormone-binding neurophysin components. 4. All the neurophysins can bind both oxytocin and [8-lysine]-vasopressin. 5. The apparent molecular weights of the neurophysins increase with increasing protein concentration as measured by equilibrium sedimentation in the ultracentrifuge. 6. Neurophysins-I and -III are of similar molecular dimensions, contain one residue of methionine per molecule and lack histidine. The minimum molecular weight of neurophysin-I obtained by amino acid analysis is 9360. Neurophysin-II is of larger molecular dimensions than neurophysins-I and -III and can be separated from these by gel filtration on Sephadex G-75. It contains no histidine or methionine, and its minimum molecular weight has been estimated as 14020 by amino acid analysis. 7. Each of the three neurophysins possesses N-terminal alanine. 8. The possible biological significance of the existence of several neurophysins within one species is discussed.
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PMID:The isolation of three neurophysins from porcine posterior pituitary lobes. 544 78

1. An improved procedure for the isolation of neurosecretory granules from the posterior lobe of the bovine pituitary gland is described. 2. Of the total oxytocic and pressor activities present in the original tissue 80% was sedimentable. 3. The granules were separated from mitochondria by prolonged centrifugation in a sucrose density gradient. During a sedimentation period of 5hr. the granules moved progressively into denser regions of the gradient and the mitochondria remained at the top. 4. The biological activities of the granules were measured: the oxytocic activity was 11.56+/-1.63 and the pressor activity was 15.60+/-3.91 units/mg. of protein. 5. A protein was isolated from a lysate of granules prepared from 40 pituitary glands. Amino acid analysis showed that it consisted of a mixture of neurophysin-I and neurophysin-II in equal proportions. It accounted for 60% of the soluble granule protein and for 50% of the total granule protein. 6. The neurophysins present in the granules are associated with 19.1 units of oxytocic and 21.1 units of pressor activity/mg. of protein. 7. Starch-gel electrophoresis revealed the presence of both neurophysins in extracts of 15 pituitary glands studied individually. 8. We conclude that the polypeptide hormones, oxytocin and [8-arginine]-vasopressin, are normally closely associated with the two neurophysins within neurosecretory granules of the pituitary gland.
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PMID:The isolation of neurophysin-I and-II from bovine pituitary neurosecretory granules separated on a large scale from other subcellular organelles. Demonstration of slow equilibration of neurosecretory granules during centrifugation in a sucrose density gradient. 563 60

1. The native hormone-binding proteins, neurophysin-I and -II, have been isolated from acetone-desiccated bovine pituitary posterior lobes. 2. Neurophysin-I and -II are present in approximately equal quantities in the tissue and are localized in the neurosecretory granules. 3. The apparent molecular weight, determined by equilibrium sedimentation of neurophysin-I, was 19000 and that of neurophysin-II was 21000; their sedimentation coefficients, S(20,w), were 1.66 and 2.02s respectively. 4. Neurophysin-I and -II are similar in amino acid composition. Neurophysin-II was distinguished from neurophysin-I by the absence of histidine. 5. The proteins form complexes with oxytocin as well as with vasopressin. Complexes of both proteins with [8-arginine]-vasopressin have been crystallized. 6. Bioassay of the pressor and oxytocic activities of the crystals shows that neurophysin-I binds three molecules of either vasopressin or oxytocin whereas neurophysin-II binds only two molecules of each hormone per molecule of protein. Complexes containing two molecules of oxytocin and one molecule of [8-arginine]-vasopressin per molecule of protein are formed by neurophysin-I and -II; both proteins appear to possess three polypeptide-binding sites/molecule.
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PMID:The isolation of the native hormone-binding proteins from bovine pituitary posterior lobes. Crystallization of neurophysin-I and-II as complexes with [8-arginine]-vasopressin. 568 29

Plasma natriuretic activity was evoked in cows and dogs by infusion of saline with or without dextran. Deproteinized samples were fractionated on both Sephadex and Bio-Gel columns; the activity was separated, the approximate molecular weight being in the region of 1000. Incubation with chymotrypsin destroyed the activity, suggesting that it might be a polypeptide. A similar activity in blood resulted from intracarotid injection of either oxytocin or either of two synthetic analogs. Possibly the latter are saluretic by virtue of a releasing action on some intracranial structure for another natriuretic peptide.
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PMID:Plasma saluretic activity: its nature and relation to oxytocin analogs. 577 12

To clarify whether various neuropeptides found in the hypothalamus act directly on a pituitary adenoma causing Nelson's syndrome, we examined the influence of these peptides on the secretion of immunoreactive ACTH, beta-endorphin, and melanotropins, the proopiomelanocortin (POMC)-derived peptides, by the cultured pituitary adenoma from a patient with Nelson's syndrome. Results showed that somatostatin-14 and somatostatin-28 suppressed the secretion of POMC-derived peptides by the adenoma and that somatostatin-28 was as potent as somatostatin-14. Other neuropeptides such as arginine vasopressin, vasoactive intestinal polypeptide, and oxytocin stimulate the secretion of POMC-derived peptides. Substance P, TRF, Met-enkephalin and Leu-enkephalin were also found to modulate the secretion of POMC-derived peptides. This suggests that the adenoma may have multiple receptors to various neuropeptides.
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PMID:Effects of various neuropeptides on the secretion of proopiomelanocortin-derived peptides by a cultured pituitary adenoma causing Nelson's syndrome. 612 87

The comparative distribution of nine peptides was examined in the L4 segment of the rat cord using the peroxidase antiperoxidase technique. The peptides examined were substance P, neurotensin, cholecystokinin, methionine-enkephalin, oxytocin, neurophysin, adrenocorticotrophin, thyrotropin releasing hormone, and vasoactive intestinal polypeptide. No transport blocking agents were used and in spite of this cell bodies containing substance P, neurotensin, cholecystokinin, and methionine-enkephalin were observed. All peptides except for thyrotropin releasing hormone were observed in fibers in laminae I and II. All peptides were present in the area around the central canal, lamina X. Each peptide had its own characteristic distribution within fibers in the gray and white matter.
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PMID:The distribution of nine peptides in rat spinal cord with special emphasis on the substantia gelatinosa and on the area around the central canal (lamina X). 616 70


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