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

The spontaneous contractility of the epididymis in the rat was recorded in vivo and the effects of the neurohypophyseal hormones were studied. Oxytocin (50 muU and 500 muU/100 g body weight) produced a progressive increase in tonus together with an increase in amplitude and frequency of the contractions. Vasopressin (100 muU and 1000 muU/100 g body weight) showed similar effects. No differences were apparent at the doses studied.
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PMID:The 'in vivo' effects of oxytocin and vasopressin on spontaneous contractility of the rat epididymis. 1 18

Neurophysin, vasopressin and oxytocin were localized in different portions of the supraopticohypophysial tract (SHT) using the unlabeled antibody enzyme technique at the ultrastructural level. In vasopressin-positive supraoptic perikarya, vasopressin and neurophysin were present in all neurosecretory granules. Within the zona interna of the median eminence, vasopressin and neurophysin were present in two populations of axons, one with granules of 1300-1500 A and one with granules of 900-1300 A. Following exposure of thin sections of median eminence to antiserum to neurophysin, reaction products were present in granules and in the extragranular cytoplasm in the axons with larger granules; in all other cases reaction product was confined to the granules. Vasopressin-positive fibers were also presented in large numbers of the zona externa of the median eminence and many terminated on the pituitary primary portal plexus. A few oxytocin fibers were present on the portal capillaries in the infundibular stalk. In the posterior pituitary all axon profiles were neurophysin positive. Neurophysin was present as both a granular and cytoplasmic pool. Vasopressin-containing axons account for 90% of the neuronal elements in the posterior pituitary and oxytocin for the remaining 10%. Findings on the subcellular distribution of these peptides are related to current theories on transport and release of neurohormones.
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PMID:Ultrastructural studies on the localization of neurohypophysial hormones and their carrier proteins. 6 Apr 34

The neurohypophyseal hormones vasopressin and oxytocin modulate memory processes. Vasopressin facilitates, while oxytocin attenuates memory consolidation and retrieval. These influences are located in different regions of the molecules. Thus, the neurohypophyseal hormones act as precursor molecules for neuropeptides involved in memory processes. The covalent ring structures of both vasopressin and oxytocin mainly affect consolidation; the linear parts, retrieval processes; while nearly the whole oxytocin or vasotocin molecule is needed for attenuation of consolidation and retrieval. Regional studies, utilizing microdissection techniques in combination with a sensitive radioenzymatic catecholamine assay, revealed a distinct pattern of effects on cerebral alpha-methyl-p-tyrosine methylester-induced catecholamine disappearance following intraventricular vasopressin administration in limbic midbrain structures. In situations in which the amount of bioavailable vasopressin in the brain is absent, as is the case in the Brattleboro rat with hereditary diabetes insipidus, or neutralized in normal Wistar rats following the intraventricular administration of antivasopressin serum, regional catecholamine disappearance in most cases is altered in a direction opposite to that observed after intracerebroventricular vasopressin administration. These results indicate that vasopressin modulates memory processes by modulation of neurotransmission in distinct catecholamine systems. Recent experiments suggest that the influence of vasopressin on memory consolidation is mediated by the dorsal noradrenergic bundle via terminal regions of this bundle.
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PMID:Neurohypophyseal principles and memory. 11 Jun 23

A continuous cell culture line was established from a bone marrow metastasis of small cell anaplastic carcinoma of the lung. The cultures were characterized by light and electron microscopy, and an unusual concentric arrangement of cells was observed, both in sectioned material from the patient's tumor and from the cell cultures. The cells had two types of specialized cell junctions and contained secretory-like granules of the type described in neuroendocrine cells. Lactic dehydrogenase isozyme patterns were the same as those observed in normal human serum, and the karyotype revealed the presence of several marker chromosomes. Vasopressin was present in the cells and secreted into the culture medium in the absence of neurophysin, as shown by the immunoperoxidase technique and radioimmunoassay. Oxytocin was also absent from cells.
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PMID:Isolation and characterization of a hormone-producing cell line from human small cell anaplastic carcinoma of the lung. 19 Apr 10

1. Recordings were made from a total of 35 antidromically identified neurones in the paraventricular (PV) and supraoptic (SO) nuclei of urethane-anaesthetized lactating rats. During recording plasma osmotic pressure was raised by 12 m-osmole/kg by injection of hypertonic solutions of NaCl, LiCl, or mannitol.2. Nine PV neurones (mean firing rate 4.2 +/- 1.0 (S.E.) spikes/sec) were classified as oxytocin cells because they gave a burst of activity before reflex milk-ejections. None of these showed a bursting (phasic) firing pattern. Ten PV neurones (mean firing rate 1.8 +/- 0.2 spikes/sec) fired phasically either before or after injection of hypertonic NaCl and were classified as vasopressin cells. The remaining six PV cells (mean firing rate 1.6 +/- 0.9 spikes/sec) showed no bursts of firing related to milk ejection and did not fire phasically.3. Increasing plasma osmotic pressure by injection of hypertonic NaCl increased the mean firing rate of PV oxytocin cells to 7.0 +/- 1.0 spikes/sec. Vasopressin cells in the PV nucleus were much less responsive and the mean firing rate after injection was 2.9 +/- 0.4 spikes/sec. The third group of PV neurones was unresponsive.4. Plasma oxytocin concentration (determined by radioimmunoassay) increased from 2.1 +/- 0.3 muu./ml. in the control period to 10.9 +/- 2.8 muu./ml. 30 min after I.P. injection of 1 ml. 1.5 M-NaCl and to 14.8 +/- 2.8 muu./ml. following injection of a second 1 ml. 1.5 M-NaCl.5. The responses of oxytocin and vasopressin neurones in the SO nucleus to an increase in plasma osmotic pressure following injections of hypertonic solutions of LiCl or mannitol were similar to those observed when plasma osmotic pressure was raised by NaCl.6. It may be concluded that both oxytocin and vasopressin cells in the neurohypophysical system are responsive to the osmotic pressure of the blood plasma rather than to Na(+) or Cl(-) concentration, that osmotic activation of oxytocin cells releases sufficient oxytocin to increase its plasma concentration, and that there may be a functional difference between the SO and PV nuclei.
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PMID:Oxytocin release following osmotic activation of oxytocin neurones in the paraventricular and supraoptic nuclei. 20 73

Transverse sections of the median eminence from fetal and neonatal rats were examined by the immunoperoxidase technique to detect the presence of oxytocin, vasopressin and neurophysin. Neurophysin was observed in the 18-day fetus. Vasopressin and oxytocin were not detected until after birth, on the 4th and 8th days respectively. There was an accumulation of material crossreactive with neurophysin and vasopressin antibodies in the palisade layer of the median eminence between the 4th and 9th days after birth. This distribution of immunoreactive material in the palisade layer was suggestive of neurosecretory substances localized in two fibre tracts on either side of the median eminence. The data are consistent with the accumulation of corticotropin releasing factor and an associated neurophysin in this area. It is suggested that the accumulation of material occurs because of the relative immaturity of the capillary loops that constitute the primary plexus of the hypophysial portal system.
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PMID:Maturation of the hypothalamo-neurohypophysial system. II. Neurophysin, vasopressin and oxytocin in the median eminence of the developing rat brain. 31 38

Vasopressin is shown to be a potent mitogen for Swiss 3T3 cells. The hormone (1--10 ng/ml) causes a striking shift of the dose--response curve for the effect of serum on thymidine incorporation by cultures of 3T3 cells arrested in the G1/G0 phase of the cell cycle. In the absence of added serum, the effect of vasopressin on DNA synthesis is greatly potentiated by insulin, epidermal growth factor, and a factor isolated from medium conditioned by simian virus 40-infected baby hamster kidney cells. The mitogenic effect of vasopressin is dependent on time and hormone concentration. In the presence of insulin, the half-maximal effect elicited by the peptide is obtained at 0.6 ng/ml. [Arg]Vasopressin and [Lys]vasopressin are equally potent. The vasopressins are 10(3)-fold more potent than oxytocin. In the presence of a low (2.5%) concentration of serum, vasopressins stimulate cell proliferation.
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PMID:Vasopressin stimulation of mouse 3T3 cell growth. 31 1

Sections of the hypothalamus, median eminence and pituitary from fetal and neonatal rats were examined with the immunoperoxidase staining technique and light microscopy. Purified antisera raised against vasopressin and oxytocin, and antisera cross-reactive with rat neurophysin were used to localize these antigens in the hypothalamo-neurohypophysial system (HNS). Neurophysin was detected throughout the HNS of the 18-day fetal rat. Vasopressin was present in the hypothalamus and pituitary of the 19-day fetus, and in the median eminence of the 4-day neonate. Oxytocin was not detected in the pituitary until 1--2 days after birth, in the hypothalamus after 4 days, and in the median eminence after 8 days. During the first days after birth the supraoptic nucleus was more mature than the paraventricular nucleus. The HNS did not approach maturity until at least 7 days after birth. The relative maturity of the supraoptic nucleus compared with the paraventricular nucleus, and the detection of vasopressin before oxytocin are evidence for the one-neuron-one-hormone theory. The data do not exclude the possibility that the fetal hypothalamo-neurohypophysial system, and perhaps the fetal hormone, vasotocin, affect the initiation and course of parturition.
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PMID:Maturation of the hypothalamo-neurohypophysial system. I. Localization of neurophysin, oxytocin and vasopressin in the hypothalamus and neural lobe of the developing rat brain. 43 49

Individual hypothalamic nuclei were microdissected from brain tissue of ten human subjects who had died suddenly while in apparent good health. Appreciable amounts of vasopressin and oxytocin immunoreactivity were found by specific radioimmunoassay in six hypothalamic nuclei including supraoptic and paraventricular nuclei. Vasopressin and oxytocin are presumed to be synthesized in supraoptic and paraventricular nuclei for axonal transport to the posterior pituitary for storage and release. Vasopressin and oxytocin in other hypothalamic nuclei may be a part of this system of neurosecretion or may serve some other function.
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PMID:Immunoreactive vasopressin and oxytocin: concentration in individual human hypothalamic nuclei. 55 8

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.
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PMID:Characterization of the responses of oxytocin- and vasopressin-secreting neurones in the supraoptic nucleus to osmotic stimulation. 56 5


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