Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The magnocellular neurosecretory cells of the supraoptic nucleus increase production and secretion of oxytocin and/or vasopressin in response to dehydration, gestation and lactation. Dynamic neuronal/glial interactions have also been shown to occur in response to these stimuli, resulting in a reversible increase in soma-somatic direct membrane apposition at these times. Chronic (lactation, 10 days of saline drinking) but not acute stimuli (4-24 h water deprivation) are further accompanied by the reversible formation of axo-somatic double synapses (one presynaptic terminal contacting two postsynaptic elements), which are virtually absent in control animals. The dendrites of these cells course ventrolaterally toward the ventral glial lamina, and have also been shown to be involved in this plasticity: dendro-dendritic direct membrane apposition and axo-somatic double synapses significantly vary with gestation and parturition. The present study investigated the dendritic zone response to both chronic and acute dehydration and rehydration. Increased dendro-dendritic membrane contacts resulted from both stimuli. Rehydration following acute dehydration resulted in a dose-dependent return to control levels, while rehydrated chronic dehydrates did not show such a return until 35 days of rehydration. The percentage of dendrites contacted by double synapses did not vary with treatment, and there were no sex differences. The recalcitrance on the part of the dendrites to return to normal following chronic dehydration may reflect a readiness to respond to renewed hormone demand.
 ...
PMID:Neuronal/glial plasticity in the supraoptic dendritic zone in response to acute and chronic dehydration. 408 95

1. Rat neurohypophysial extracts have been examined by polyacrylamide-gel electrophoresis. 2. Three of the proteins were tentatively identified as neurophysins by their acidic nature and their disappearance after dehydration of the animals. 3. These proteins were radioactive 24h after intracisternal injection of [(35)S]cysteine. 4. Two of the proteins were present in much greater quantities than the third, and these two were present in the gland in the same ratio as the hormones vasopressin and oxytocin. 5. One of these proteins was absent from glands of rats homozygous for diabetes insipidus but present in heterozygous animals. 6. It is suggested that these two proteins are the vasopressin-neurophysin and oxytocin-neurophysin of the rat.
 ...
PMID:Tentative identification of a vasopressin-neurophysin and an oxytocin-neurophysin in the rat. 513 37

Immunoreactive-vasopressin, -oxytocin, -dynorphin, -dynorphin-(1-8), -alpha-neo-endorphin and -[Met]enkephalin were, in each case, present in greater concentrations in dorsal as compared to ventral, and lumbo-sacral as compared to cervico-thoracic, spinal cord. These differences were significantly more pronounced for vasopressin and oxytocin than for the other peptides. Lesions of the hypothalamic paraventricular nucleus depleted levels of immunoreactive-vasopressin and -oxytocin throughout the cord whereas levels of the opioid peptides therein were unaffected. In contrast, destruction of either the supraoptic or suprachiasmatic nucleus failed to change the content of immunoreactive-vasopressin, -oxytocin or any of the opioid peptides in the cord. Dehydration for 3 days depressed levels of immunoreactive-vasopressin, -oxytocin and -dynorphin in the neurointermediate lobe of the pituitary. In distinction, the levels of these were not modified in the spinal cord. Further, treatment with the synthetic corticosteroid, dexamethasone, elevated levels of immunoreactive-vasopressin, -oxytocin and -dynorphin in the neurointermediate pituitary whereas these were unaffected in the spinal cord. It is concluded that vasopressin and oxytocin in the spinal cord are predominantly derived from the paraventricular nucleus, localized in dorsal lumbo-sacral regions of the cord and insensitive to endocrinological manipulations. These pools may, thus, be modulated differently from their counterparts in the neurohypophysis and have a differing role, possibly in the control of the primary processing, autonomic or motor junctions. Further, there is no evidence from these or our prior studies for a close interrelationship of spinal cord vasopressin with dynorphin-related peptides (or oxytocin with [Met]enkephalin), likewise in contrast to the neurohypophysis.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Vasopressin and oxytocin in the rat spinal cord: distribution and origins in comparison to [Met]enkephalin, dynorphin and related opioids and their irresponsiveness to stimuli modulating neurohypophyseal secretion. 614 93

Rats dehydrated up to 12 days were given intraperitoneally methoxamine hydrochloride in a daily dose of 1.0 mg/100 g of initial body weight. The only dose of methoxamine injected into normally hydrated animals did not influence significantly the oxytocic activity neither in the hypothalamus nor in the neural lobe. Following four days of dehydration a distinctly more marked depletion of the hypothalamic (both in the NSO and NPV region) and neurohypophysial oxytocin content was found in animals treated with methoxamine. For the neurohypophysis, a similar effect has been noted under severe dehydration (8th and 12th day) as well.
 ...
PMID:The release of neurohypophysial hormones as influenced by stimulation of alpha-adrenergic transmission in long-term dehydrated male white rats. Information 2: hypothalamic and neurohypophysial oxytocic activity. 626 78

Under conditions of equilibrated water metabolism a single dose of methoxamine increased the content of vasopressin in the hypothalamus as well as that of oxytocin both in the hypothalamus and neurohypophysis. During dehydration the depletion of hypothalamic and neurohypophysial vasopressin was more marked in methoxamine-treated animals; this effect, however, was absent in the neurohypophysis on the 2nd day and in the hypothalamus on the 8th day of water deprivation. After two days of dehydration methoxamine inhibited the decrease of oxytocin content in the hypothalamus; simultaneously (2nd and 4th day of dehydration) it intensified this process in the neurohypophysis. During rehydration methoxamine impaired the renewal of vasopressin both in the hypothalamus and neurohypophysis; this effect was most marked on the 8th day of rehydration. On the contrary, it favoured somewhat the renewal of hypothalamic oxytocin in rehydrated rats (such an event was not found on the 8th day of rehydration). Moreover, methoxamine restrained initially (on the 2nd and 4th day of rehydration) the restoration of neurohypophysial oxytocin stores; following eight days of rehydration an opposite effect was here found. It is concluded that the response of the vasopressinergic and oxytocinergic neurons to alpha-adrenergic stimulation, brought about by using methoxamine as pharmacological tool, seems to be depended on the actual state of water metabolism. Impulses from the osmoreceptors may be therefore of some importance in modifying the change in vasopressin and oxytocin synthesis, transport and release resulting from stimulation of alpha-adrenergic transmission through neural chains including units susceptible to methoxamine.
 ...
PMID:The vasopressor and oxytocic activities of the hypothalamus and neurohypophysis influenced by stimulated alpha-adrenergic transmission during dehydration and subsequent rehydration in the white rat. 632 69

Various lines of evidence have suggested that astrocytes play a dynamic role in control of hormone synthesis and release from the CNS. The model system most studied has been the rat hypothalamo-neurohypophysial system, consisting chiefly of the supraoptic and paraventricular nuclei and their axonal terminals. Neurons of this system manufacture and secrete oxytocin and vasopressin. Electron microscopic studies have shown that certain physiological conditions (e.g., dehydration, lactation) produce increases in direct apposition among these neurosecretory cells, an effect due to withdrawal of glial processes from between the neurons. Neurohypophysial astrocytes (pituicytes) show dynamic interactions with the neurons at the level of the terminals, by engulfing them and interposing processes between the terminals and the basement membrane when hormone demand is low. Pituicyte processes retract from both areas when hormone demand is high, allowing the neuronal terminals direct access to the perivascular space. Recently, osmotic manipulations (in the physiological range) have shown that these changes can be produced in vitro in neurohypophysial explants without stimulated hormone release. Experiments on cultured adult rat pituicytes have revealed similar morphological changes in response to noradrenaline. These changes were reversed or blocked by propranolol. The increase in direct soma-somatic apposition (7-9 nm separation) of magnocellular neurons could produce a tonic rise in (K+)o which would increase protein synthesis and contribute to the raised excitability of these neurons. Also, the removal of interposed glia could allow the formation of gap junctions and specialised synapses which are known to occur between these neurons. These in turn may participate in producing the coordinated firing that maximizes hormone release. The interactions of pituicytes with the terminals in the neurohypophysis suggests that these astrocytes are also a part of the mechanism of control of hormone release.
 ...
PMID:Dynamic neuronal-glial interactions in hypothalamus and pituitary: implications for control of hormone synthesis and release. 638 46

Despite the absence of vasopressin, Brattleboro homozygous (DI) rats concentrate their urine to hypertonic levels when deprived of drinking water for 24 h. Glomerular filtration rate (GFR) falls concurrently and might contribute to the increased concentrating ability. The present studies concerned the time course of the changes in concentrating ability and GFR during the early hours of dehydration. Experiments were performed in 10 chronically catheterized conscious DI rats in the normally hydrated control state and during 3 h of fluid deprivation. Urine osmolality (Uosmol) increased from 97 +/- 6 (SE) to 325 +/- 11 mosmol/kg H2O at 3 h. Averaged over the 3 h, neither GFR nor effective renal blood flow changed significantly (103 +/- 2 and 106 +/- 4% of control, respectively). Fractional excretion of sodium (FENa) rose markedly from 0.3 +/- 0.1 to 1.3 +/- 0.1% at its peak. Clearly, a fall in GFR cannot explain the rise in Uosmol during the first 3 h. Plasma oxytocin (OT) increased from 5.6 +/- 0.8 to 36.4 +/- 4.5 pg/ml after 3 h of dehydration. In additional experiments, d(CH2)5-D-Phe-VAVP, an antidiuretic antagonist (anti-ADH), was administered to eight DI rats after 3-h dehydration. Control, 3-h dehydration, and post-anti-ADH values were, respectively: for Uosmol, 102 +/- 7, 347 +/- 14, 145 +/- 11 mosmol/kg H2O; for GFR, 1,003 +/- 43, 1,042 +/- 59, 866 +/- 54 microliter X min-1 X 100 g body wt-1; for FENa, 0.4 +/- 0.1, 1.4 +/- 0.1, 0.5 +/- 0.1%. The decreases following anti-ADH were all statistically significant. We conclude that OT is released during the early hours of dehydration in the DI rat and has at least three renal effects. It causes a natriuresis, it maintains renal hemodynamics and GFR during the volume contraction, and it elicits a weak antidiuretic response.
 ...
PMID:Antidiuretic effect of endogenous oxytocin in dehydrated Brattleboro homozygous rats. 647 23

The effects of acute cellular or extracellular dehydration on milk intake via suckling were determined in rats 5, 10, 15, and 20 days of age. Milk was made available 10 times to each rat pup by the intravenous infusion of oxytocin to anesthetized test dams. Prior to 15 days of age, milk intake was not affected by either intracellular or extracellular dehydration. In rats 15 days and older, however, both forms of dehydration reduced milk intake at the nipple. Thus, dehydration starts to inhibit suckling behavior at the onset of weaning, when food and water are both taken directly from the environment by the developing animal.
 ...
PMID:Transitions in the dehydration-induced inhibition of milk intake in suckling rats. 648 19

A sensitive and specific radioimmunoassay method for simultaneous measurement of plasma arginine vasopressin (AVP) and oxytocin (OT) has been developed utilizing an extraction technique on DEAE Sephadex A25. This procedure resulted in mean recoveries of 70.7% (AVP) and 65.4% (OT) in the peptide range of 5 to 100 pg/4 ml. The sensitivity of the assay is 0.5 pg/tube for AVP and 2 pg/tube for OT. The lower limit of detection for plasma extracts was 1.2 pg AVP/ml and 5 pg OT/ml plasma. Employing this method in normal human non smokers and ad libitum fluid the basal levels (mean +/- SE) of plasma AVP are 3.5 +/- 0.2 pg/ml in males and 4.6 +/- 0.4 pg/ml in females and the basal concentrations of plasma OT are 5.1 +/- 0.3 pg/ml in males and 5.4 +/- 0.3 pg/ml in females. Dehydration and water loading produced significant changes in plasma AVP and OT concentrations and a significant correlation exists between plasma AVP and plasma (r = 0.96, p less than 0.001) and urinary (r = 0.84, p less than 0.01) osmolality, but not between plasma OT concentrations and plasma (r = 0.11, NS) and urinary (r = 0.27, NS) osmolality. These results suggest that a wide range of physiological and pathophysiological changes in plasma AVP and OT can be simultaneously measured by the extraction procedure and the radioimmunoassay described.
 ...
PMID:Simultaneous radioimmunoassay for plasma arginine-vasopressin and oxytocin using DEAE Sephadex A 25 extraction. 650 2

The magnocellular neurosecretory cells of the supraoptic nucleus increase production and release of oxytocin and/or vasopressin under such conditions as parturition, lactation and dehydration. These stimuli have been shown to result in increased direct apposition of neuronal membranes and the formation of double synapses (one presynaptic terminal contacting two postsynaptic elements) within the supraoptic nucleus at the level of the cell bodies. These morphological changes are due to the retraction of the thin glial processes which are normally interposed between adjacent neurons. The present study was undertaken to ascertain whether, and to what extent, neuronal/glial plasticity occurs in the dendritic zone (i.e. the ventral glial laminar area) of the supraoptic nucleus. The instances of two or more dendrites with membrane in direct apposition (dendritic bundles), the number of dendrites per bundle, the amount of dendritic membrane in direct apposition and the percentage of dendrites contacted by double synapses were quantified at the ultrastructural level in virgin female, prepartum (21 days of gestation), postpartum (day of parturition) and lactating rats. All parameters measured varied significantly with the hormone demand states created by pregnancy and lactation, apparently due to glial retraction. Moreover, in the 2-24 h period between pre- and postpartum there was a significant increase in the number of dendrites per bundle, dendritic membrane in direct apposition and the percentage of dendrites contacted by double synapses. This time course corresponds to the known increased release of oxytocin and vasopressin at parturition. These findings constitute the first demonstration that dendritic bundles and double synapses occur in the ventral glial lamina/dendritic zone of the supraoptic nucleus and vary under the physiological conditions of pregnancy, parturition and lactation.
 ...
PMID:Neuronal/glial plasticity in the supraoptic dendritic zone: dendritic bundling and double synapse formation at parturition. 652 78


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>