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

Different biological effects of Ag+ (10(-4) M) were found depending on its presence in the outer or the inner solution bathing the frog skin. A marked increase in the electrical conductance and an interference with the action of oxytocin and amiloride were found only when Ag+ was added to the outer solution. Results suggest that Ag+ affects several transport processes, in particular the permeability of the Na entry pathways.
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PMID:Effects of Ag+ on frog skin: interactions with oxytocin, amiloride and ouabain. 86 23

Cytochemical methods using silver proteinate, silver methenamine an potassium ferrocyanide + OsO4 for ultrastructural detection of glycoproteins allow, in the posthypophysis and the magnocellular nuclei of the rat, differentiation of two types of fibres and neurons: one type containing negative granules with a homogenous content of low electron density, the second type containing granules which demonstrate a ring shaped deposit either of silver or of potassium ferrocyanide-osmium complex, likely to be related to a glycoprotein component. The difference between these two types is increased by prestaining "en bloc" with uranyl acetate before the silver proteinate reaction. A similar investigation was carried out on the vasopressin deficient Brattleboro rat; the neurosecretory material, present in some endings and neurons only, is of the nonreactive type, so that it appears justified to correlate the reactivity of granules with vasopressin, consequently to distinguish neurones and fibres containing vasopressin from those in which oxytocin is quantitatively the main hormonal peptide. This conclusion is strongly supported by the fact that percentages of reactive and negative endings, as determined on this basis in the posthypophysis of normal rats from two different strains, are in good agreement with biochemical data reported in the literature.
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PMID:Cytochemical duality of neurosecretory material in the hypothalamo-posthypophysial system of the rat as related to hormonal content. 87 84

A study is made of the effect of synthetic oxytocin on the mechanograms and electromyograms of the stomach and small intestines of 11 wakeful and 7 chloralose-anaesthesized dogs. Oxytocin was administered intravenously in doses of 0.5 to 2.0 IU/kg for the anaesthesized dogs. The mechanograms were recorded by means of the balloon-kymographic method, the electromyograms-by silver macroelectrodes implanted in the muscle wall. In all animals oxytocin decreased the tone and abolished the peristaltic contractions and the spike-potentials in the stomach and in the intestines for 8 to 15 min. This effect of oxytocin is not eliminated by adreno-, cholino- and gangliolytics. Besides these changes, oxytocin administered in wakeful dogs reduces two or three times the frequency of the basic electric rhythm (BER) in the stomach from 10 s to 3 min and increases the propagation of BER in the small intestine from 10 s to 10 min. The effect of oxytocin on gastric and intestinal BER is eliminated by cholinolytics and gangliolytics and it is not manifested in the small pouch of Heindenhein. A direct myogenic mechanism of oxytocin effect on the activity of the gastro-intestinal smooth muscle is discussed, as well as the effect mediated by vagal nerves and cholinergic receptors.
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PMID:Effect of synthetic oxytocin on the motor and bioelectrical activity of the stomach and small intestines (in vivo). 121 Nov 87

Fine, varicose oxytocin-containing nerve fibers have been demonstrated in the hypothalamic arcuate nucleus in rats. Using Phaseolus vulgaris leukoagglutinin as an anterograde tracer, fine neuronal fibers of paraventricular nucleus origin could be seen throughout the arcuate nucleus. Using double immunostaining, oxytocin-immunoreactive varicose fibers were observed around or in the close vicinity of beta-endorphin-immunoreactive neurons. Silver-gold-labeled oxytocin-immunoreactive presynaptic boutons were shown to make synaptic contacts with diaminobenzidine-labeled beta-endorphin-immunoreactive neurons by electron microscopy. These findings provide morphological evidence for a possible influence of oxytocin on the activity of the brain beta-endorphin system at the hypothalamic level.
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PMID:Oxytocin nerve fibers innervate beta-endorphin neurons in the arcuate nucleus of the rat hypothalamus. 127 46

It has been suggested that oxytocin, besides its milk-ejecting activity, is also involved in the hormonal regulation of the mammary gland secretory cells. The available data, however, are conflicting. In this study two independent experiments, separated by a certain time interval show that oxytocin intravenously administered to mice at days 10-14 of lactation diminished the incorporation of [3H]leucine into the mammary gland tissue by 32 and 53 per cent, respectively. The neurohormone was co-injected with the tracer amino acid. The radioactivity taken up by the secretory cells was estimated by light microscopic autoradiography. The autoradiograms were evaluated by visual silver grain counting. Tissue radioactivity was measured by liquid scintillation counting. A milk stasis in the mammary gland induced by depriving the mice of suckling two hours before tracer injection had no influence on the secretory activity of the glandular cells. It is assumed that oxytocin has a direct effect on the milk-producing cells, and that the reduction in measurable radioactivity caused by the neurohormone may be due to an accelerated intracellular passage of labelled milk proteins.
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PMID:The influence of exogenous oxytoxin on labelling of secretory epithelium of mouse mammary gland by [3H]leucine, evidenced by autoradiography. 130 60

We describe a rapid method for the preparation and binding site labeling of cryostat sections for use in light microscopy. Instead of using antibodies to bind to specific sites, substance P, delta-sleep-inducing peptide, oxytocin, and dopamine were covalently attached to BSA and then the BSA-ligand complex was adsorbed on 5-nm colloidal gold particles. Bioassays carried out on isolated organs indicated that the physiological activity of the ligand GPL complex was maintained. Most of the technical steps included use of an ordinary microwave oven (MWO), with tissues exposed for less than 1 min in any given step. Cryostat sections of unfixed rat brain were pre-incubated for 50 sec in the MWO in a Tris-buffered solution (pH 7.4) containing 1.5% BSA, then further incubated for 50 sec in the MWO in Tris-buffered solution containing 1% gelatin and the diluted colloidal gold suspension. After washing, the preparations were postfixed for 30 sec in the MWO in 5% formaldehyde solution, pH 7.4. Finally, the cell-bound gold particles were enlarged by a silver-enhancing process and counterstained. Preparations observed at high magnification provided excellent resolution of the cell binding sites. Positive and negative controls performed by addition of BSA-conjugated ligands to the pre-incubation and incubation medium, and displacement of the markers by an excess of unbound ligand in the pre-incubation or the incubation medium, showed the specificity of the tissue labeling.
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PMID:Microwave-aided binding of gold-protein-ligand (GPL) complexes. Light microscopic observations in the rat brain. 137 31

Corticotropin-releasing factor (CRF) has been reported to be expressed in oxytocin-containing magnocellular neurosecretory neurons of the paraventricular (PVN) and supraoptic (SON) nuclei, and in Barrington's nucleus, a pontine micturition center. Each of these cell groups is known to play a role in fluid and electrolyte homeostasis. To gain a better understanding of the role of CRF in this context, the effects of osmotic stimulation and volume loading on CRF mRNA levels in the PVN, SON and Barrington's nucleus were examined using in situ hybridization histochemistry with an 35S-labeled cRNA probe. Adult male rats received either normal tap water (control), or hypertonic (2%) saline (HS) for up to 3 days. In a second experiment, normal saline was infused through a jugular vein cannula at 6 ml/h for 3 days; control rats were cannulated but received no infusion. Relative levels of CRF mRNA were compared by estimating both the number of positively hybridized cells and the density of silver grains in emulsion-dipped autoradiograms. HS treatment resulted in marked increases in CRF mRNA in the magnocellular neurosecretory system. All recognized oxytocinergic cell clusters, i.e., the anterior, medial and posterior magnocellural subdivisions of the PVN, the dorsal aspect of the SON, and components of the accessory magnocellular system, displayed this effect. By contrast, HS treatment resulted in significant decreases in CRF mRNA levels in the parvocellular (hypophysiotropic) division of the PVN and in Barrington's nucleus. By contrast, volume loading, which failed to affect plasma osmolality, significantly increased CRF mRNA levels in Barrington's nucleus.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of corticotropin-releasing factor mRNA in neuroendocrine and autonomic neurons by osmotic stimulation and volume loading. 148 95

In the paraventricular nucleus (PVN) of the rat hypothalamus, we determined synaptic associations between oxytocin (OXT)-containing magnocellular neurons and parvocellular neurons containing corticotropin-releasing factor (CRF) by using a double immunolabeling technique in 7 animals. In single vibratome sections of the hypothalamus, immunoreactive CRF and OXT were labeled with silver-gold particles and diaminobenzidine (DAB) chromogen, respectively. By light microscopy CRF-containing fibers appeared to be black dots, some of which encircled magnocellular perikarya labeled with brown DAB chromogen in the PVN. By electron microscopy we discriminated OXT neurons having fine DAB-chromogen particles distributed throughout the cytoplasm and on large secretory granules from CRF neurons having dense coarse particles of silver-gold. Occasional CRF axons terminated on perikarya or dendritic processes of OXT neurons, making synaptic contacts. The terminals which were characterized by having clusters of small clear vesicles and a few dense core vesicles showed equal thickenings of pre- and postsynaptic membranes at the synaptic junctions.
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PMID:Synaptic associations between oxytocin-containing magnocellular neurons and neurons containing corticotropin-releasing factor in the rat magnocellular paraventricular nucleus. 151 23

Antibodies to oxytocin and noradrenalin were utilized in an immunocytochemical study of the caudal ventrolateral medulla of the rat brainstem. Noradrenalin was visualized by using antibodies to noradrenalin and by means of a silver-gold intensification of diaminobenzidine, whereas oxytocin could be demonstrated in the same section by using the diaminobenzidine precipitate as a marker. At the light microscopic level, oxytocin fibers were densely distributed around the A1 cell bodies. At the ultrastructural level, oxytocin-containing fibers were seen to terminate synaptically onto noradrenalin-containing neurons. Previous studies have shown that electrical stimulation of A1 neurons selectively activates vasopressin-secreting neurons in the supraoptic nucleus. Therefore, separate electrophysiological studies were set up, in which we observed that oxytocin infusions (100-200 pg) into the A1 area enhanced the activity of 16 out of 19 putative vasopressin-secreting neurons and elicited no response from any of 10 oxytocin-secreting neurons. This finding suggests that some of the parvicellular neurons in the paraventricular nucleus of the hypothalamus, from which the A1 neurons derive their oxytocin innervation, can activate the A1 cell group via this peptidergic neurotransmitter. One of the consequences of A1 neuronal activation is enhanced firing of hypothalamic supraoptic (and paraventricular) vasopressin-secreting neurons, and a consequent rise in plasma vasopressin.
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PMID:Oxytocin localization and function in the A1 noradrenergic cell group: ultrastructural and electrophysiological studies. 209 24

In situ hybridization (ISH) was used to study at the electron microscope level, the subcellular localization of oxytocin (OT) mRNA in the rat hypothalamic magnocellular neurons. Rat brains were fixed with paraformaldehyde and glutaraldehyde and vibratome slices were incubated with a 25-base synthetic oligonucleotide complementary to OT mRNA and labelled at the 3'-end with [3H]dCTP. Hybridized slices were embedded in Epon after post-fixation with osmium tetroxide and cut into ultrathin sections that were processed for ultrastructural radioautography. OT mRNA was observed in magnocellular neurons of supra-optic and paraventricular nuclei in the vibratome sections. On ultrathin sections, the cytological preservation appeared to be satisfactory. Except for a few silver grains over the nucleus, sometimes close to its membrane, most grains were localized over the cytoplasm of some magnocellular neurons, where they frequently overlapped the endoplasmic reticulum. To decrease exposure time, ISH was also performed with OT probes labelled with a long tritiated tail. In this case, clusters of silver grains occurred over the cell nuclei not only in magnocellular neurons but also in non-secretory neurons and even in glial cells. However, an excess of poly C added to the hybridization buffer strongly decreased this non-cytoplasmic labelling. In conclusion, the results obtained with the short-tailed oligonucleotides demonstrate that these synthetic oligonucleotides have possible applications for the ultrastructural localization of mRNAs and constitute a powerful tool for the dynamic study of cellular mRNA processing in several physiological and experimental conditions.
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PMID:Ultrastructural localization of oxytocin mRNA in the rat hypothalamus by in situ hybridization using a synthetic oligonucleotide. 216 99


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