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

Developmental changes in levels of oxytocin in the blood and the pituitary gland and in oxytocin responses to oxytocin-releasing stimuli were investigated in the rat from the fetus close to term to the 40-day-old young adult. The oxytocin content of the pituitary gland rose gradually from fetuses of 21 days of gestation to 40-day-old rats. Pituitary oxytocin levels expressed in terms of body weight also increased up to day 25 after birth and declined slightly thereafter. In contrast, serum concentrations of oxytocin increased from day 21 of pregnancy up to day 5 after birth but were stable thereafter. Oxytocin levels in both blood and the pituitary gland were equal in 23-day-old fetuses and 1-day-old infants born on day 22 of pregnancy. There was no difference in serum and pituitary oxytocin levels in newborn pups and unborn littermates of day 22 or 23 of gestation. The i.p. injection of hypertonic saline induced a significant increase in serum oxytocin levels on day 5 and later, but no effect in the fetus on day 22 of gestation and in the 1-day-old infant. The responsiveness to the osmotic stimuli increased after 5 days of age. The i.p. injection of diethyldithiocarbamate, a noradrenaline synthesis inhibitor, or phenobarbitone was effective in raising blood oxytocin levels only in rats older than 10 and 20 days of age respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Functional development of the oxytocin release mechanism and its role in the initiation of parturition in the rat. 404 38

The tonic contractions which are extremely resistant to removal of the external Ca were investigated in the rat vas deferens and myometrium. Both the noradrenaline response in the vas deferens and the oxytocin response in the myometrium could be repeatedly produced without appreciable diminution in Ca-free solution for more than 24 hrs. On the other hand, the tissue Ca content decreased exponentially after Ca-removal with a half time of 130-180 min. When Ca was readmitted, no indication of the early transient contraction was observed in the subsequent response in Ca-free solution, but the response was reduced compared with the response before Ca readmission. Verapamil suppressed the response in the presence of Ca, while it had very weak inhibitory effect even at 10 microM. Calmodulin antagonists of phenothiazine derivatives had a strong inhibitory effect on Ca-induced contractions, whereas they had very weak effects on the receptor-mediated contraction in Ca-free solution. Another calmodulin antagonist, W-7 suppressed both Ca-induced contraction and the contractions independent of external Ca. HA-1004, a vasodilator which has a structure similar to W-7, reduced the receptor-mediated contraction in Ca-free solution without much effect on Ca-induced contractions. These results may suggest that the receptor-mediated contractions resistant to Ca-removal are caused by some process without a contribution of the Ca-calmodulin system.
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PMID:Contraction of smooth muscle in Ca-free solution. 405 13

The ultrastructural relationships between neurophysin (NP)- or vasopressin (VP)-containing neurons and catecholamine terminals in the paraventricular nucleus and supraoptic nucleus of the rat were observed by means of a technique combining immunocytochemistry using NP I/II or VP antiserum with autoradiography after [3H]noradrenaline (NA) injection or 5-hydroxydopamine (5-OHDA) uptake. NP- or VP-like immunoreactive nerve cell bodies and fibers received synaptic contacts from a large number of immunonegative axon terminals. The presynaptic elements that innervate the neurosecretory neurons were studied. Axon terminals labeled with [3H]NA or 5-OHDA made synaptic contacts with NP- or VP-like immunoreactive nerve cell bodies and fibers. Furthermore, axodendritic and/or axo/axonic and axosomatic synapses occurred between the same NP- or VP-like immunoreactive neurons. These findings suggest that at least NA- and 5-OHDA-containing neurons play some important role in the control of neurosecretion in the NP- or VP-producing neurons of the rat hypothalamus and that the axon collaterals of NP- and VP-containing neurons make synaptic contacts with the same kind of neurons to form a recurrent collateral circuit.
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PMID:Electron microscopic examination of the catecholaminergic innervation of neurophysin- or vasopressin-containing neurons in the rat hypothalamus. 408 97

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

The frog urinary bladder undergoes, in some conditions, a marked increase of its water permeability when incubated in hypertonic media. This increase was observed with various nonpermeant solutes. It seems to result from the shrinkage of an osmo-sensitive compartment of the tissue, probably the epithelial cells. Many similarities were found between this effect and the physiological increase in water permeability (hydrosmotic response) elicited by antidiuretic hormone (ADH): both were dependent on the physiological state of the animals, and although the response was slower after hyperosmolar than after hormonal challenge, the patterns of response were similar, and in both cases markedly dependent on bathing solution temperature. Norepinephrine and prostaglandin E(1), which in this tissue reduce the hydrosmotic action of ADH, presumably by inhibiting the adenyl cylase also reduced the effect of hyperosmolarity. Conversely this effect was potentiated by incubation in the presence of oxytocin, exogenous cyclic AMP, and theophylline, conditions in which the intracellular concentration of cyclic AMP is increased. These data demonstrate that the response to hyperosmolarity is elicited, at least partly, by mechanisms also involved in the physiological hydrosmotic response to ADH.
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PMID:The effect of hypertonic media on water permeability of frog urinary bladder. Inhibition by catecholamines and prostaglandin E 1 . 434 37

1 A sensitive method of assaying oxytocin using the superfused mouse mammary gland is described. The method is shown to be reliable, accurate and precise. Assays are performed automatically and the preparation is stable for at least 18 hours.2 The preparation is relatively insensitive to bradykinin, histamine, 5-hydroxytryptamine, angiotensin, prostaglandin F(2alpha), adrenaline and noradrenaline. The contractions produced by acetylcholine can be abolished by atropine without the sensitivity to oxytocin being affected.3 Vasopressin has a variable activity on the preparation; its potency can be as high as one-fifth that of oxytocin.4 It is concluded that this method compares favourably with other published methods.
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PMID:Bioassay of oxytocin on the superfused mammary gland of the mouse, using an automatic apparatus. 436 53

1 The sensitivity of a wide range of isolated tissues to oxytocin was investigated. The longitudinal muscle strip of duck pulmonary vein proved the most suitable tissue for use with the superfusion technique, contracting to concentrations to oxytocin as low as 10 muu/ml.2 The duck pulmonary vein superfused with Krebs solution was contracted by oxytocin, the vasopressins, adrenaline, noradrenaline, 5-hydroxytryptamine, histamine and angiotensin II. Pre-treatment of the preparation with phenoxybenzamine (1-2 mug/ml) abolished the contractions to catecholamines and reduced the effects of histamine and 5-hydroxytryptamine without affecting the sensitivity to oxytocin.3 The pulmonary vein contracted when superfused with blood from an anaesthetized dog. This contraction was accompanied by a non-specific loss of responsiveness. When the pulmonary vein was superfused with Krebs solution that had been dialysed against blood the initial contraction was greatly reduced or abolished as was the loss in responsiveness.4 Oxytocin was stable in circulating dog's blood but approximately 50% was bound to plasma proteins. Oxytocin was not destroyed in the pulmonary circulation or the hind limbs. In the doses used oxytocin had a half-life of 60-90 s in the circulation of the dog under steady-state conditions. Disappearance occurred chiefly in the visceral vascular beds.
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PMID:A sensitive method for the assay of oxytocin in the circulating blood. 445 24

1. Pressure changes in the submaxillary and parotid ducts of dogs, induced by nerve stimulation or intravenous injection of drugs, were studied.2. Pressure rises could be elicited by parasympathetic stimulation and by acetylcholine and methacholine, even when no secretion was evoked. These effects were abolished by atropine.3. Similarly, sympathetic stimulation, adrenaline, noradrenaline and phenylephrine raised the pressure in both glands, also in the absence of secretion. Dihydroergotamine abolished these effects. Isoprenaline increased the pressure in the submaxillary duct, but only when it caused secretion. This effect was abolished by propranolol. In the parotid gland isoprenaline caused neither secretion nor pressure rise. It is concluded that the myoepithelial cells of the two glands are supplied with alpha-adrenoceptors.4. Doses of histamine, bradykinin, kallidin and physalaemin which caused no salivary secretion raised the duct pressure even when dihydroergotamine, propranolol and atropine had been given.5. Angiotensin and 5-hydroxytryptamine increased the pressure only in some experiments. Oxytocin caused very little or no pressure rise. Vasopressin had no effect of its own but reduced the pressure raising effects of nerve stimulation or drugs.
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PMID:The pharmacology of salivary myoepithelial cells in dogs. 534 69

Extracellular application of some peptides (oxytocin, Lys-vasopressin, Leu-enkephalin) to neuron RPal induced pacemaker potentials generation and initiated or increased bursting activity. Norepinephrine and prostaglandins E1 and E2 effects on neuron RPal electric activity were qualitatively similar to those produced by oxytocin and Lys-vasopressin. Dibutyryl-cAMP, papaverine (phosphodiesterase inhibitor) and sodium fluoride (nonspecific adenylate cyclase activator) induced or potentiated bursting activity. It is supposed that oxytocin, Lys-vasopressin, Leu-enkephalin, norepinephrine and E group prostaglandins effects are mediated by intracellular processes related to activation of adenylate cyclase and increase of cAMP level in the neuron.
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PMID:[Reactions of an identified edible snail neuron to application of peptides, mediators, prostaglandins, and cyclic nucleotides]. 611 55

Oxytocin (OXT) attenuates memory processes and endogenous OXT might be regarded as an amnesic neuropeptide. In this study, the mode of action of OXT on brain catecholaminergic neurotransmission has been analyzed. Peripheral injection of OXT facilitated the alpha-MPT-induced disappearance of noradrenaline (NA) in the mesencephalon. Dopamine (DA) disappearance was inhibited in the mesencephalon and facilitated in the striatum. The accelerated striatal DA disappearance was not observed if the peptide was given together with alpha-MPT, but only if OXT was injected after alpha-MPT treatment. Intraventricular injection of OXT or des-glycinamide-oxytocin (DG-OXT) caused a decrease in the DA disappearance in the mesencephalon, whereas central administration of anti-oxytocin serum (anti-OXT) accelerated the DA disappearance in the same region. The data raise the possibility that DA utilization in the mesencephalon may be correlated with the influence of OXT on CNS processes.
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PMID:Effects of oxytocin, des-glycinamide-oxytocin and anti-oxytocin serum on the alpha-MPT-induced disappearance of catecholamines in the rat brain. 613 95


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