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)

Recordings of intratubal pressure in women reveal a complex pattern of tubal contractions. Overall activity of the fallopian tube is increased during ovulation. During the luteal phase of the menstrual cycle, activity is depressed but never suppressed. The fallopian tube remains active during gestation in contrast with the uterus which is quiescent. The early puerperal tube displays a pattern of activity similar to that recorded during the late luteal phase of the menstrual cycle. Activation occurs during suckling and in response to exogenous oxytocin, prostaglandins, nor-adrenergic compounds, and ergot derivatives. It is concluded that contractility of the fallopian tube is less influenced by ovarian steroids than that of the uterus.
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PMID:Contractility of the fallopian tube. 17 Jan 70

Adenylate cyclase and the [8-lysine]vasopressin receptor were solubilized from pig kidney medulla membranes using the nonionic detergent Triton X-100. Optimal conditions for solubilization were under continuous stirring in a medium containing 0.5% (/v) Triton X-100, 100 mM Tris-HCl, pH 8, and 10 mM MgCl2. Both adenylate cyclase activity and [3H][8-lysine]vasopressin binding activity were recovered in a -26,000 X g supernatant of detergent-treated membranes. The yield of solubilized adenylate cyclase was nearly 100%. The soluble enzyme was no longer sensitive to antidiuretic hormone but was slightly activated by sodium fluoride. The affinity of the soluble receptor for [8-lysine]vasopresin was les than that of the membrane-bound receptor (mean apparent Km values, respectively 10(-7) M and 2 X 10(-8) M), however binding cooperativity was preserved. Hill coefficients were 1.42 for the soluble receptor and 1.50 for the membrane receptor. The soluble receptor discriminated as efficiently as did the membrane receptor between [8-lysine-a1vasopressin and oxytocin. The yield of spolubilized receptor was only 30% despite the fact that all binding activity had disappeared from the residual pellet of detergent-treated membranes. When the membranous receptors were occupied before solubilization and the latter was performed under conditions in which dissociation of the hormone-receptor comples is slow, i.e. at low temperature, 65% to 100% of the hormone-receptor complex was recovered in the soluble fraction. The soluble hormone-receptor complex partially dissociated on rewarming whereas the free hormone concentration was kept unchanged in the medium. The residual binding capacity, which was 30% of the initial value, was identical with that determined when the receptor was solubilized in free form before incubation with labeled hormone. It was concluded that (a) solubilization of the receptor molecules was complete, (b) during solubilization two forms of the receptor appear, of which only one is accessible to the hormone, (c) occupancy of the receptor by the hormone prevented the formation of the nonaccessible form, and (d) some component or components of the soluble fraction might be responsible for the loss in apparent affinity.
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PMID:Solubilization of the [8-lysine]vasopressin receptor and adenylate cyclase from pig kidney plasma membranes. 17 Feb 74

The data demonstrate that the contractions of hypocontractile active labor and normal spontaneous labor are different in several measures in addition to maximal amplitude. Furthermore, when the pathophysiology is corrected by the use of oxytocin, the contractions resemble those of normal spontaneous labor except in the maximal rate of tension development. Our data tend to support the subcellular model of uterine contractility, although the incompleteness of these models limits interpretation.
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PMID:Intrauterine pressure wave form characteristics in hypocontractile labor before and after oxytocin administration. 17 Aug 27

Recent data on the effects of neurohypophysial peptides at the cellular level are discussed with respect to the two basic processes involved in peptide hormone action--i.e., specific recognition of the information contained in the hormonal molecule and the transformation of this information into a stimulus leading to the final biological response. Four main aspects of this general problem are considered. A. Hormone-Receptor Interaction: Recent contributions in this field concern partial analysis of the three-dimensional conformation of oxytocin and vasopressin moleculal cells of the mammalian kidney. Conformational analysis of oxytocin and vasopressin molecules leads to the conclusion that, in solution, these peptides probably have a compact and highly stabilized three-dimensional configuration. Models have been proposed that provide a valuable clue to the interpretation of structure-activity relationships among natural hormones and many structural analogues. Binding studies with tritiated oxytocin and vasopressin have permitted determination of the kinetic parameters of hormone-receptor interaction in amphibian epithelial cells and mammalian kidney. B. Stimulus Generation: The nature of the primary stimulus generated by hormone-receptor interaction is still unknown. In the epithelial target cells of the amphibian skin and bladder and of the mammalian kidney, one of the first consequences of hormone-receptor interaction is the activation of membrane-bound adenylate cyclase. Analysis of the correlations between hormonal binding and adenylate cyclase activation suggests that activation is a function of receptor occupation rather than of the number of hormonal molecules interacting with the receptor per unit of time. On medullary adenylate cyclase of pig kidney, the relation between receptor occupancy and enzyme activation was found to be complex and nonlinear. The effects of several agents (calcium, nucleotides) on receptor occupancy and adenylate cyclase activation have been described. In mammalian uterus and other smooth muscle target cells, there is no evidence for direct involvement of cyclic AMP in the contractile response to oxytocin and other neurohypophysial peptides.
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PMID:Stimulus-response coupling in neurohypophysial peptide target cells. 17 91

Myometrial activity was recorded in vivo in unrestrained pregnant rats from day 19 of gestation using radiotelemetry. The effects of short-term infusions of theophylline, dibutyryl cyclic AMP and 8-bromo-cyclic GMP were investigated. All three compounds caused a decrease in oxytocin-induced, prostaglandin F2alpha-induced and spontaneous uterine activity. After cessation of the infusion of these compounds uterine activity returned to near pre-infusion levels within approximately 15 min in most animals. The possible roles of cyclic nucleotides in the control of myometrial contraction are discussed in the light of these observations.
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PMID:Modification of myometrial activity in vivo by administration of cyclic nucleotides and theophylline to the pregnant rat. 17 77

Rabbits were anesthetized with urethane, and the concentration of 3',5' cyclic adenosine monophosphate (cAMP) in cerebrospinal fluid (CSF) was measured before and after injection into the cisterna magna of the following biologically active peptides and amines; adrenocorticotropin (ACTH), beta-melanocyte-stimulating hormone (beta-MSH), choroid plexus peptide IIF, arginine vasopressin, oxytocin, glucagon, epinephrine, serotonin, histamine, and acetylcholine. Only epinephrine and the lipolytic-melanotropic peptides ACTH, beta-MSH, and IIF influenced cAMP. Five to 500 mug ACTH caused a 3 to 10X increase in cAMP within 30 min; the concentration of nucleotide returned to baseline within 60-90 min after 5 or 50 mug, and remained elevated for at least 120 min after 500 mug. Effects of the same magnitude and tempo as those caused by 5 to 500 mug ACTH were produced by .1 to 10 mug beta-MSH and 5 to 500 mug IIF. Epinephrine at doses of 5 to 500 mug caused rises in cAMP of similar degree as the same dose of ACTH or peptide IIF, but the peak value was not reached until 60 to 90 min after injection.
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PMID:Effect of intrathecal injection of melanotropic-lipolytic peptides on the concentration of 3',5' cyclic adenosine monophosphate in cerebrospinal fluid. 17 24

With immunohistochemical techniques, products from both the parvicellular system (such as Gn-RH) and from the magnocellular system (vasopressin, oxytocin, and neurophysins) have been shown to be present in the neurons ending around the hypothalamopituitary portal capillary system. A neurosurgical technique for prolonged collection of pituitary stalk blood has been developed. Gn-RH, vasopressin, and neurophysins have been found in large amounts in pituitary stalk blood. Gn-RH levels were found to vary in a pulsatile fashion, thereby providing direct evidence for hypothalamic modulation of the discharge of LH by the pituitary. The finding of large amounts of estrogen-neurophysin in portal vein blood adds further evidence to the hypothesis that "estrogen" neurophysin may play a role in the control by the hypothalamus over the secretion of gonadotropins.
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PMID:Neurohormonal control of gonadotropic secretion in primates. 17 89

Transitional epithelium lining rabbit urinary bladders was isolated and studied in vitro. The homogeneity of the isolated epithelium was demonstrated by light and electron microscopical monitoring as well as cell culture studies. Transitional epithelium responded to epinephrine and prostaglandin E1 (PGE1) in the presence of 2mM 1-methyl, 3-isobutylxanthine (MIX) with increases in intracellular levels of cyclic adenosine 3':5'-monophosphate (cyclic AMP). Corticotropin, aldosterone, insulin, parathyroid hormone and vasopressin were slightly but significantly stimulatory under similar conditions. Glucagon and oxytocin were not stimulatory at the concentrations tested. The effects of epinephrine and PGE1 were potentiated by 2mM MIX 20-fold or greater. The cells were slightly more sensitive to PGE1 then to epinephrine. The prostaglandin produced a noticeable response at about 10nM, while effects of epinephrine were discernible at 0.1muM. Maximal responses to both effectors were seen at about 10muM. The action of 10muM epinephrine, but not 10muM PGE1, was completely abolished by 0.1mM propranolol. Responses to combinations of epinephrine and PGE1 were additive. Cyclic AMP accumulated in the incubation medium of transitional epithelial cells exposed to epinephrine, PGE1, MIX, or combinations of the agonists. The appearance of cyclic AMP in the medium was slow compared to the rate of intracellular accumulation, but reached significant levels following prolonged stimulation.
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PMID:The effects of hormones on cyclic adenosine 3':5'-monophosphate accumulation in transitional epithelium of the urinary bladder. 17 60

The milk-ejecting activity of oxytocin analogues modified in the aminoterminal part of the molecule was determined in experiment on rats in vivo. As compared with oxytocin, the analogues did not have significantly higher milk-ejecting activity and there was no dissociation of the two basic oxytocin-like activities.
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PMID:Milk-ejecting and uterotonic activities of oxytocin analogues in rats. 17 84

During secretion of the neurohypophysial hormones, oxytocin and vasopressin, secretory granule membrane is added to the plasma membrane of the axon terminals. It is generally assumed that subsequent internalization of this additional membrane occurs by endocytosis. In order to study this process, we have traced the uptake of intravenously injected horseradish peroxidase by neurohypophysial axons in rats and golden hamsters. Peroxidase reaction product within the secretory axons was found mainly in vacuolar and C-shaped structures of a size comparable with or larger than the neurosecretory granules. Our observations suggest that these large horseradish peroxidase (HRP)-impregnated vacuoles arise directly by a form of macropinocytosis. Morphometric analysis indicated that this form of membrane retrieval increased significantly after the two types of stimuli used, reversible hemorrhage and electrical stimulation of the pituitary stalk. Microvesicular uptake of HRP was found to be comparatively less.
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PMID:Secretion-related uptake of horseradish peroxidase in neurohypophysial axons. 18 85


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