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)

1. The effects of Na+ on vasopressin release and on redistribution of Ca2+, Na+ and H+ in isolated rat neurohypophysial nerve endings have been studied. 2. Substituting Na+ for a non-permanent cation produced a pronounced and sustained release of vasopressin. This increase occurred in the absence of external Ca2+ and in nerve endings loaded with the Ca2+ chelator dimethyl-BAPTA (1,2-bis-(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid). 3. The effect of Na+ was independent of a rise in intracellular Ca2+ as judged by the measurement of [Ca2+]i using the indicator fura-2 and 45Ca2+ efflux studies. Although Na+ could release Ca2+ from internal reservoirs the small elevation in [Ca2+]i induced by Na+ could not explain the large and sustained increase in vasopressin secretion. 4. The channel blockers TTX (tetrodotoxin), D888 (desmethyoxyverapamil), N144 (5-nitro-2-(phenylpropylamino)-benzoic acid) or SITS (4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid) could not prevent the Na(+)-dependent increase in vasopressin release. Similarly this increase was not affected by metabolic inhibitors (Ruthenium Red and KCN) nor by CCCP (carbonyl cyanide m-chlorophenylhydrazone), an uncoupler of oxidative phosphorylation. 5. Selectivity among monovalent cations to promote secretion was found with the largest effect on the secretory response being produced by Na+. Similarly Cl- was found to be the most potent anion studied for inducing, in the presence of Na+, an increase in neurohormone release. 6. Measuring [Na+]i by means of the Na+ indicator SBFI showed that the extent of the secretory response was correlated with the intraterminal Na+ concentration. 7. The Na(+)-induced, Ca(2+)-independent release of vasopressin occurred by exocytosis as judged (i) by the linear relationship between the amount of vasopressin secreted and that of the co-localized neurophysin and (ii) by the demonstration that the extracellular marker horseradish peroxidase was only found in endocytotic vacuoles and not in the cytoplasm of the stimulated nerve endings. 8. The Na(+)-dependent secretory response found on addition of extracellular Na+ was not the result of the change in internal pH as measured with the indicator BCECF and as mimicked by addition of propionic acid. 9. Addition of Na+ to digitonin- or streptolysin-O-permeabilized nerve endings in the presence or absence of Ca2+ also gave rise to an increase in vasopressin secretion. 10. It is concluded that an increase in internal Na+ per se can promote, in the absence of a rise in intracellular Ca2+, an increase in neuropeptide secretion.
 ...
PMID:Sodium-evoked, calcium-independent vasopressin release from rat isolated neurohypophysial nerve endings. 750 28

Taurine is an inhibitory amino acid that hyperpolarizes magnocellular neurosecretory neurons. To determine which cell types in the rat supraoptic nucleus contain taurine, we used a monoclonal antibody raised against a taurine conjugate. Preembedding immunocytochemistry was carried out at the light and electron microscopic levels using diaminobenzidine and gold-substituted silver-intensified peroxidase as markers. We report the presence of taurine in all cellular compartments of the supraoptic nucleus, except axons, with variable labeling intensities among the different compartments. Few cell bodies of magnocellular neurons were immunoreactive, but many distal dendrites and some proximal ones showed weak-to-moderate levels of immunoreactivity. Strong immunoreactivity was found over glial cell bodies and their processes, in particular in the ventral glial lamina of the supraoptic nucleus. Large astrocytic processes labeled with the taurine antibody included the endfeet participating in the glial limitans around capillaries and at the ventral surface of the hypothalamus. Other types of immunoreactive astrocytic profiles were found scattered within the neuropil where these processes participated in different interactions with the neuronal elements of the supraoptic nucleus. Immunoreactive glial expansions, sometimes even the main process of the glial cell, engulfed axonal boutons. Other labeled glial processes were found between two magnocellular perikarya or closely apposed to the membrane of axonal boutons contacting the neuronal cell bodies. The frequent finding of closely apposed glial and dendritic elements bearing different levels of taurine-like immunoreactivity suggests that exchange of taurine between those two compartments may occur. We propose that taurine could be released from supraoptic glia by a small decrease in osmolarity or by receptor-mediated mechanisms during conditions of low hormonal (vasopressin and/or oxytocin) needs. Such released taurine could then act on presynaptic or postsynaptic sites, or both, to exert its neuromodulatory actions.
 ...
PMID:Taurine immunoreactivity in the rat supraoptic nucleus: prominent localization in glial cells. 761 71

In the developing and adult human paraventricular (PVN) and supraoptic (SON) nucleus, a large proportion of neurons contains the catecholamine-synthesizing enzyme tyrosine hydroxylase (TH). In the present study we investigated the possible colocalization of TH with oxytocin (OXT) or vasopressin (VP) in the adult and neonatal PVN and SON. Adjacent paraffin sections were incubated simultaneously with two antibodies: a polyclonal against TH and a monoclonal against OXT or VP and stained with a double peroxidase-antiperoxidase/alkaline phosphatase method. We observed that TH-immunoreactive(IR) perikarya in the human PVN and SON were also positive for OXT or VP. A clear difference between the neonates and adult cases of our sample was observed in the proportion of TH-IR neurons that colocalize OXT or VP. In the neonates the majority of the TH-IR perikarya was also stained for VP, while only few TH-IR neurons were also positive for OXT. The opposite was observed in the adults, where the majority of the double-stained TH-IR neurons colocalizes OXT while only few TH-IR perikarya appear to contain VP. Our study establishes the colocalization of TH with OXT or VP in the adult and neonatal PVN and SON and indicates that antemortem factors such as perinatal hypoxia might increase TH-immunoreactivity of the VP neurons in man.
 ...
PMID:Colocalization of tyrosine hydroxylase with oxytocin or vasopressin in neurons of the human paraventricular and supraoptic nucleus. 769 71

A protocol was developed combining non-radioactive in situ hybridization histochemistry with enzyme based immunohistochemistry, detect the expression of mRNA in phenotypically defined neurons. Free-floating brain sections were hybridized with the oligonucleotide probes which have been 3'-end labelled with biotin-11-dUTP. The hybridized probe was visualized by a combined avidin-biotin bridge method, anti-avidin immunohistochemistry, and horseradish peroxidase detection using diaminobenzidine as a substrate. The in situ hybridization step yielded a very stable reaction product enabling subsequent immunohistochemical reactions using horseradish peroxidase and benzidine dihydrochloride as a chromogen. Magnocellular neurons of the hypothalamo-neurophypophysial system synthesize either vasopressin or oxytocin; water deprivation and chronic saline ingestion are potent stimuli for the expression of both of the genes encoding these neuropeptides. A number of other neuropeptides with putative transmitter action are synthesized in magnocellular neurons during such stimulation. Experiments were performed to explore whether neuropeptide Y immunoreactivity is present within magnocellular vasopressin mRNA-expressing neurons of the hypothalamo-neurophypophysial system. The results clearly demonstrated that neuropeptide Y-immunoreactive elements were present within a number of magnocellular vasopressin mRNA-containing cells. In addition, immunohistochemical detection of the neuropeptides ocytocin and cholecystokinin was carried out on sections hybridized non-radioactively for vasopressin; as expected vasopressin mRNA did not co-exist with cholecystokinin, whereas a few oxytocin immunoreactive neurons in osmotically stimulated animals also contained vasopressin mRNA. The developed method makes possible the immunohistochemical detection of intracellular antigens with concomitant detection of intracellular mRNA.
 ...
PMID:Simultaneous detection of neuropeptides and messenger RNA in the magnocellular hypothalamo-neurohypophysial system by a combination of non-radioactive in situ hybridization histochemistry and immunohistochemistry. 769 98

The response of immunocytochemically identified hypothalamic axons innervating the rat spinal cord was examined at varying times after cord hemisection in a model of axonal injury using the paraventriculospinal projection. The purpose was to determine whether these long descending peptidergic axons would show signs of regrowth after injury. From 1 to 180 days after hemisection, horizontal sections of the spinal cord were stained with peroxidase immunocytochemistry. Antiserum against neurophysin was used to identify axons projecting from the hypothalamic paraventricular nucleus to the spinal cord. The paraventricular nucleus innervates all rostrocaudal segments of the cord, yet the projection is not massive, allowing the trauma response of individual axons to be studied. Immediately caudal to a T4 hemisection, axons began decreasing in number by 2 days after surgery. Ten days postoperatively, only a few axons could be found caudal to the cut; these remaining axons arose from the contralateral cord. A substantial increase in the number of stained axons was found rostral to the hemisection 3-12 weeks after surgery. In that an increase in axon number could be due to both increasing staining efficacy and sprouting, the orientation of axons in control and hemisected rats was studied. Three millimeters rostral to the hemisection, axons had a greater variance in orientation and were more likely to project medially out of the dorsolateral white matter compared with the contralateral control side. Rostral to the hemisection, a statistically significant two- to fourfold increase in the number of branches per axons was found in comparison to the contralateral control side. Axons were found in the dorsal white matter 4 months after surgery; in controls, immunostained axons were not found here. At all intervals after surgery, structures suggestive of growth were found, including terminal growth cones and lateral filopodia and lamellipodia extending from axons whose distal ends had been severed by hemisection. Similar structures were not found in control spinal cord. Together, these data suggest that after cord hemisection, axons from the paraventricular nucleus sprout rostral to the injury.
 ...
PMID:Paraventriculospinal tract as a model for axon injury: spinal cord. 786 Jul 81

The retinal innervation, cytoarchitectural, and immunohistochemical organization of the suprachiasmatic nucleus (SCN) was studied in the domestic sheep. The SCN is a large elongated nucleus extending rostrocaudally for roughly 3 mm in the hypothalamus. The morphology is unusual in that the rostral part of the nucleus extends out of the main mass of the hypothalamus onto the dorsal aspect of the optic chiasm. Following intraocular injection of wheat-germ agglutinin-horseradish peroxidase or tritiated amino acids, anterograde label is distributed throughout the SCN. Retinal innervation of the SCN is bilaterally symmetric or predominantly ipsilateral. Quantitative image analysis demonstrates that, although the amount of autoradiographic label is greatest in the ventral and central parts of the nucleus, density varies progressively between different regions. In addition to the SCN, retinal fibers are also seen in the medial preoptic area, the anterior and lateral hypothalamic area, the dorsomedial hypothalamus, the retrochiasmatic area, and the basal telencephalon. Whereas the SCN can be identified using several techniques, complete delineation of the nucleus requires combined tract tracing, cytoarchitectural, and histochemical criteria. Compared with the surrounding hypothalamic regions, the SCN contains smaller, more densely packed neurons, and is largely devoid of myelinated fibers. Cell soma sizes are smaller in the ventral SCN than in the dorsal or lateral parts, but an obvious regional transition is lacking. Using Nissl, myelin, acetylcholinesterase, and cytochrome oxidase staining, the SCN can be clearly distinguished in the rostral and medial regions, but is less differentiated toward the caudal pole. Immunohistochemical demonstration of several neuropeptides shows that the neurochemical organization of the sheep SCN is heterogeneous, but that it lacks a distinct compartmental organization. Populations of different neuropeptide-containing cells are found throughout the nucleus, although perikarya positive for vasoactive intestinal polypeptide and fibers labeled for methionine-enkephalin are predominant ventrally; neurophysin-immunoreactive cells are more prominent in the dorsal region and toward the caudal pole. The results suggest that the intrinsic organization of the sheep SCN is characterized by gradual regional transitions between different zones.
 ...
PMID:The suprachiasmatic nucleus in the sheep: retinal projections and cytoarchitectural organization. 795 5

The discovery of immediate early genes (IEG) has provided neuroscientists with a new functional mapping technique. Labelling of neural tissue for the protein product of IEG provides an activity map with single-cell resolution. When combined with labelling for the chemical identity of the neuron, this provides a powerful tool for the investigation of specific cell populations along a neuraxis. Here we describe in detail a method which allows simultaneous bright-field visualization of neurochemically identified cells displaying increased IEG expression. This technique is evaluated in tissue from rats subjected to stimuli known to induce the expression of the IEG c-fos in various medullary catecholaminergic and hypothalamic neurosecretory cell groups. A 2-colour immunoperoxidase technique was used to visualize Fos, the nuclear protein product of c-fos, and the cytoplasmic antigens tyrosine hydroxylase (TH), phenylethanolamine N-methyl transferase (PNMT), oxytocin (OT) and vasopressin (VP). This involved simultaneous application of primary antibodies raised in different species followed by sequential application of appropriate biotinylated secondary antibodies and the avidin-biotin-peroxidase technique. Fos was visualized with nickel-intensified diaminobenzidine (Ni-DAB) in the first sequence while TH, PNMT, OT or VP were visualized with DAB alone, resulting in readily distinguishable black and amber reaction products, respectively. This dual immunoperoxidase technique is time saving compared to techniques using sequential application of primary antibodies and avoids the disadvantages associated with fluorescence techniques.
 ...
PMID:Neurochemical identification of fos-positive neurons using two-colour immunoperoxidase staining. 810 Jun

The neuropeptide hormones arginine-vasopressin (AVP) and oxytocin (OT) have been found in the ovarian follicles and corpora lutea (CL) of many eutherian mammals. In ruminants, there is persuasive evidence that luteal OT is involved in luteolysis via stimulation of uterine prostaglandins. However, based on scant evidence, the marsupial ovary has been viewed as being devoid of OT-like and AVP-like peptides. In this study, corpora lutea from the brushtail possum were examined for OT, AVP, and mesotocin (MT) by a combination of reverse phase HPLC, radioimmunoassay, and immunohistochemistry (IHC). Peptides extracted from each of five CL were separated by HPLC and each fraction was assayed for AVP, MT, and OT. Two immunoreactive peaks were found, corresponding to AVP and MT standards. The amount of each peptide was 8.7 +/- 2.22 pmol MT/g (mean +/- SEM) and 5.7 +/- 1.0 pmol AVP/g, respectively. The mean MT/AVP ratio was 1.55 compared to 0.26 for the pituitary. IHC (streptavidin-peroxidase method) of Bouin's-fixed CL showed staining for MT in the cytoplasm of luteal cells which was absent in stromal tissue and nonluteal ovarian tissue. Not all luteal cells were immunopositive and no topographical distribution of stained cells was observed. IHC localization of AVP was not attempted. It was concluded that the CL of the brushtail possum contains low quantities of MT and AVP, which in the case of MT is probably synthesized by the immunochemically staining cells of the CL.
 ...
PMID:Mesotocin and arginine-vasopressin in the corpus luteum of an Australian marsupial, the brushtail possum (Trichosurus vulpecula). 817 26

The catecholaminergic innervation of neurons that contain oxytocin in the paraventricular nucleus (PVN) of the rat hypothalamus was examined by a combination of methods in the same tissue sections at the electron-microscopic level as follows: (1) Rats were treated with 5-hydroxydopamine (5-OHDA) with peroxidase-antiperoxidase (PAP) staining of sections for oxytocin prior to embedding. (2) Preembedding immunoperoxidase staining with avidin-biotin complexes was used to demonstrate tyrosine hydroxylase (TH) activity, with postembedding staining with immunocolloidal gold for visualization of oxytocin. (3) Prior to embedding, a double-staining technique was used that was based on consecutive staining with silver-gold-intensified PAP complex and 3,3'-diaminobenzidine. We used an antiserum against oxytocin and an antiserum against dopamine-beta-hydroxylase (DBH) for localization of antigens. We found that TH- and DBH-like immunoreactive terminals were distributed throughout the rat hypothalamus and were abundant in all parts of the PVN. Ultrastructural observations revealed 5-OHDA-labeled, TH- or DBH-like immunoreactive axon terminals that contained granular vesicles (70-80 nm in diameter) and small clear synaptic vesicles (30-50 nm in diameter). The terminals appeared at times to be making synapses with cell bodies and with the processes of oxytocin-containing neurosecretory neurons in the PVN. These findings provide morphological evidence for a direct synaptic influence of catecholaminergic elements on the secretory activity of oxytocin-containing neurosecretory neurons in the rat hypothalamic PVN.
 ...
PMID:Catecholaminergic innervation of oxytocin neurons in the paraventricular nucleus of the rat hypothalamus as revealed by double-labeling immunoelectron microscopy. 821 44

A combination of retrograde cell body labeling and immunohistochemistry was employed to elucidate how oxytocinergic fibers make contact with sympathetic preganglionic neurons (SPNs) in the rat spinal cord from T1 to T4. SPNs were labeled retrogradely using cholera toxin subunit B (CTb) or horseradish peroxidase-conjugated CTb. Oxytocin-immunoreactive (ir) fibers were found in the intermediate zone, including the sympathetic preganglionic subnuclei. In the central autonomic nucleus and the intercalated nucleus, brown-stained oxytocin-ir varicosities or terminals were frequently observed to stud black-stained dendrites of SPNs. Electron microscopical observations showed that oxytocin-ir terminals form synapses with dendrites or soma of the sympathetic preganglionic neurons. The terminals contained numerous small clear round vesicles and a few large, cored vesicles. These results clearly show that a large proportion of SPNs are innervated by oxytocin-containing fibers. The origin of these fibers is discussed, and it is concluded that they are probably descending fibers from the paraventricular nucleus of the hypothalamus.
 ...
PMID:Oxytocinergic innervation to the upper thoracic sympathetic preganglionic neurons in the rat. A light and electron microscopical study using a combined retrograde transport and immunocytochemical technique. 875 Oct 57


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