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

1. Extracellular action potentials were recorded from forty antidromically identified single units in the supraoptic nucleus of lactating, urethane-anaesthetized female rats. The activity was monitored both during reflex milk ejection and during an increase of 10-15 m-osmole/kg in plasma osmotic pressure induced by intraperitoneal injection of 1 ml. of 1.5 M-NaCl solution.2. About half (eighteen) the cells showed a burst of activity before reflex milk ejection and were dubbed oxytocin cells. Oxytocin cells responded to a hypertonic injection with a smooth sustained threefold increase in firing rate.3. The remainder (twenty-two) showed no burst of activity before reflex milk ejection and were dubbed vasopressin cells. Vasopressin cells doubled their firing rate as plasma osmotic pressure increased. Neither cell type increased its firing rate after injections of isotonic NaCl.4. A phasic firing pattern was rarely seen in slow firing vasopressin cells (< 2 spikes/sec) but was seen in almost all vasopressin cells (twelve out of fourteen) firing between 3 and 8 spikes/sec. Above 8 spikes/sec, some vasopressin cells fired continuously. Phasic firing was only once encountered in an oxytocin cell.5. The firing rate of both oxytocin and vasopressin cells decreased when plasma osmotic pressure was reduced 10-15 m-osmole/kg by an intragastric water load of 10 ml.6. Hypothalamic cells lying just outside the supraoptic nucleus did not show a consistent response to injection of hypertonic NaCl.7. Clearly, both oxytocin and vasopressin cells are osmoresponsive, but phasic firing is characteristic of stimulated vasopressin cells. Thus, osmotic activation allows discrimination between oxytocin- and vasopressin-secreting neurones.
J Physiol 1977 Sep
PMID:Characterization of the responses of oxytocin- and vasopressin-secreting neurones in the supraoptic nucleus to osmotic stimulation. 56 5

1. A technique is described for obtaining a myometrial preparation devoid of endometrium, from the uterus of the rat in oestrus. 2. Acetylcholine and prostaglandin F2alpha (PGF2alpha) produced concentration-effect curves with the same maximal tensions and slope on the whole uterus and myometrial preparations. Concentration-effect curves to bradykinin and oxytocin on the myometrial preparation were altered, resulting in a shift to the right and a decreased maximum response compared with those produced by the whole uterus. 3. Indomethacin produced greater antagonism of the responses of the whole uterus to bradykinin and oxytocin than to acetylcholine and PGF2alpha, whereas responses of the myometrium to all four agonists were similarly depressed. 4. Responses of the myometrial preparation to a range of concentrations of bradykinin and oxytocin were significantly enhanced by prior sensitization of the myometrium to PGF2alpha. This significant enhancing effect of PGF2alpha was only seen with the threshold dose of acetylcholine. 5. It appears that the mechanism of action of bradykinin and oxytocin on the rat uterus involves both a direct action and an indirect action. The indirect action possibly involves release of prostaglandin(s) from the endometrium.
Br J Pharmacol 1978 Sep
PMID:The action of bradykinin and oxytocin on the isolated whole uterus and myometrium of the rat in oestrus. 56 12

Labour can be induced by different methods: there are conductive, indirect and direct approaches. Conductive techniques are reversible and, as a rule, successful only in women approaching term. Indirect techniques, i.e. low and high amniotomy, are irreversible; they should be carried out only for a precise indication and are associated with certain hazards. Direct techniques, i.e. administration of oxytocin and, recently, of prostaglandins, need an intravenous infusion. The dosage of the drug per minute differs according to the obstetrical situation and the aim of the approach. Calculated statistical data of the tonus, the intensity, the frequency and the uterine activity were summarized in order to evaluate the effect of induction of labour. The induction of labour is associated with hazards and risk to the fetus and/or the mother. Labour induction must be avoided in obstetrical situations which preclude a vaginal delivery. The necessity of labour induction occurs primarily under circumstances in which the further continuation of pregnancy is associated with increased hazards to the mother and/or the child.
Wien Klin Wochenschr 1978 Sep 29
PMID:[Induction of labour (author's transl)]. 69 57

Vasopressin and oxytocin pathways were specifically localized in glutaraldehyde-paraformaldehyde fixed rat brains, with the use of the unlabelled antibody enzyme method and purification of the first antiserum. Vasopressin and oxytocin containing pathways were traced from the paraventricular nucleus towards the dorsal and ventral hippocampus, the nuclei of the amygdala, substantia nigra and substantia grisea, nucleus tractus solitarius, nucleus ambiguus and to the substantia gelatinosa of the spinal cord. In addition, a vasopressin containing pathway between the suprachiasmatic nucleus and the lateral habenular nucleus was demonstrated. The possible nature (axons or dendrites) and role of these extrahypothalamic fibres is discussed in relation to water balance, milk ejection and avoidance behaviour.
Cell Tissue Res 1978 Sep 26
PMID:Intra- and extrahypothalamic vasopressin and oxytocin pathways in the rat. Pathways to the limbic system, medulla oblongata and spinal cord. 69 26

Using appropriate amino acid active esters (3 eq.) in presence of HOBt (1 eq.) and employing DPM protection for the thiol function of cysteine, a rapid synthesis of oxytocin in the solid phase has been accomplished. The DPM group has been removed by sodium-liquid ammonia reduction since boiling TFA is ineffective. Desaminooxytocin and 4-Thr-oxytocin have been synthesized using lesser quantities of amino acid active esters (1.5 eq.) in presence of HOBt (1 eq.), but the durations of coupling are longer. The solid-phase synthesis of desamino-oxytocin using appropriate Boc-amino acids in presence of DCCI in toluene medium has been described. Toluene does not exert any significant accelerating influence on the coupling rate as it does when active esters are employed.
Int J Pept Protein Res 1978 Sep
PMID:Solid-phase synthesis of oxytocin, desaminooxytocin and 4-Thr-oxytocin using active esters in presence of 1-hydroxybenzotriazole. 70 Sep 21

Cultured pineal ependymal cells from rat fetuses release into their incubation media immunoreactive neurophysin. The presence of neurophysin was assessed by radioimmunoassay. The culture medium was found to contain 440 pg neurophysin per mg protein.
Experientia 1978 Sep 15
PMID:Evidence for in vitro release of neurophysin by the rat pineal gland. 72 May 37

As part of a program in which we are attempting to design and synthesize antagonists of the vasopressor response to arginine-vasopressin (AVP), [1-deaminopenicillamine]arginine-vasopressin (dPAVP), [2-O-methyl)tyrosine]-arginine-vasopressin [Tyr(Me)AVP], and [1-deaminopenicillamine,2-(O-methyl)tyrosine]arginine-vasopressin [dPTyr(Me)AVP] were synthesized by the solid-phase method and assayed for vasopressor, antidiuretic, and oxytocic activities. Tyr(Me)AVP has a vasopressor potency of 9.7 +/- 0.5 units/mg and an antidiuretic potency of 386 +/- 36 units/mg. These values are 2.5 and 120%, respectively, of the corresponding potencies of AVP. The analogue is an antagonist of the in vitro response to oxytocin (pA2 = 7.44 +/- 0.12). dPAVP has an antivasopressor pA2 of 7.45 +/- 0.11. Its antidiuretic potency is 42.2 +/- 2 units/mg, 2.5% that of its parent, 1-[deamino]arginine-vasopressin (dAVP). It is an antagonist of the in vitro response to oxytocin (pA2 value = 6.93 +/- 0.10). dPTyr(Me)AVP has an antivasopressor pA2 of 7.96 +/- 0.05 and an antidiuretic potency of 3.5 +/- 0.5 units/mg. It is also an antagonist of the in vitro oxytocic response to oxytocin (pA2 value = 7.61 +/- 0.14). It is thus one of the most potent vasopressor antagonists reported to date.
J Med Chem 1978 Sep
PMID:Design of potent antagonists of the vasopressor response to arginine-vasopressin. 72 51

Tissue factor apoprotein and relipidated tissue factor preparations extensively hydrolyze bradykinin, Lys-bradykinin, Met-Lys-bradykinin, substance P, [Asp1, Ile5]-angiotensin II, [Asp1, Ile5]-angiotensin I, and human fibrinopeptide A while acting more slowly on [Sar1, Ile5]-angiotensin II, [Me2Gly1, Ile5]-angiotensin II, bradykinin potentiating pentapeptide from B. jararaca, luteinizing hormone-releasing hormone, melanocyte stimulating hormone-release-inhibiting factor (Pro-Leu-Gly-NH2), and oxytocin. No hydrolysis of thyrotropin-releasing factor or bradykinin potentiating nonapeptide from B. jararaca is observed. Relipidated and apoprotein tissue factor act at identical rates under the conditions of the assay. Dansylation and chromatography of tissue factor-peptide incubation mixtures further indicate that relipidated and apoprotein tissue factor also hydrolyze peptides by identical mechanisms. No fewer than six bonds are hydrolyzed in bradykinin while the angiotensins and substance P are degraded to constituent amino acids. Only the N-terminal alanine is released from fibrinopeptide A. 2-Mercaptoethanol greatly inhibits the hydrolysis of bradykinin by relipidated tissue factor.
Proc Soc Exp Biol Med 1976 Sep
PMID:The hydrolysis of biologically active peptides by bovine lung tissue factor (thromboplastin). 78 91

Using an immunoperoxidase technique at the ultrastructural level, vasopressin (VP) and neurophysin (NP) were localized in the axons of the median eminence of normal and adrenalectomized rats. Whereas VP and NP were generally found in 150-nm granules in the internal zone of the normal rat median eminence, in the adrenalectomized rat, many granules of about 80 to 100 nm in diameter were found to contain NP and VP in the external zone of the median eminence.
Am J Anat 1976 Sep
PMID:Electron microscopic immunohistochemical localization of vasopressin and neurophysin in the median eminence of normal and adrenalectomized rats. 78 92

Visualized by immunocytochemistry vasopression and neurophysin are observed in perikarya of the supraoptic and paraventricular nuclei and their fibers going to the neurohypophysis. In addition to these classical sites, vasopressin and neurophysin are located in perikarya of the organum vasculosum of the lamina terminalis and of the suprachiasmatic nuclei. Outside the hypothalamus, neurophysin-positive perikarya are found in the triangular nucleus of the septum which is a part of the limbic system. Vasopressin and neurophysin are contained in two types of extrahypothalamic fibers. Large caliber fibers are found in the amygdala, small caliber fibers in the septum and thalamus. The presence of neurosecretory perikarya and fibers outside the hypothalamus may be related to psychotropic effects of peptide hormones.
Pharmakopsychiatr Neuropsychopharmakol 1976 Sep
PMID:Demonstration of extrahypothalamic peptide secreting neurons. A morphologic contribution to the investigation of psychotropic effects of neurohormones. 79 99


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