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

The apical membrane of frog skin contains two types of pathways which allow the passage of several monovalent cations in the absence of external Ca2+. Differences between the two pathways concern their open-close kinetics, selectivity, and the affinity for several blocking agents. Type S channels open and close relatively slowly, whereas type F channels display fast open-close kinetics. Both channel types allow the passage of Na+, K+, and Rb+ currents which are blocked by divalent cations and La3+ added to the extracellular side. Type F channels are permeable for Cs+ which is, however, excluded from type S channels. Shifts in open-close kinetics induced by Mg2+ occur at concentrations below 5 microM for type F channels, whereas more than a tenfold higher dose is required for the type S pathway. UO2(2+) concentrations up to 100 microM only occlude type S channels while 100 microM tetracaine selectively blocks type F channels. Apical membranes of toad urinary bladder, cultured amphibian renal epithelia (A6), and toad colon contain only type F channels. In toad bladder and A6 cells volume expansion strongly activates this pathway. Macroscopic currents carried by Ba2+ and Ca2+ could be recorded after activation of toad bladders with oxytocin and treatment of the apical surface with nanomolar concentrations of Ag+, which seems to interact with a site located at the channel interior.
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PMID:Poorly selective cation channels in apical membranes of epithelia. 750 54

Disulfide bond formation in S-acetamidomethyl (Acm) cysteine-containing peptides by successive treatments with silver trifluoromethanesulfonate (AgOTf) and dimethyl sulfoxide (DMSO)/aqueous HCl is described. An S-Acm cysteine was found to be quantitatively converted into cysteine by deprotection of the Acm group with AgOTf followed by DMSO/aqueous HCl treatment. Under these reaction conditions, no significant side reactions were observed with oxidation-sensitive amino acids such as Met, Tyr and Trp. Oxytocin and a Trp-containing peptide, urotensin II, were prepared by this method. Furthermore, regioselective two disulfide bond formation was found to be feasible by the combination of air oxidation and the AgOTf-DMSO/HCl system. This strategy has been successfully applied to the syntheses of tachyplesin I and endothelin I, which have two disulfide bonds and a Trp residue in the molecule.
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PMID:Disulfide bond-forming reaction using a dimethyl sulfoxide/aqueous HCl system and its application to regioselective two disulfide bond formation. 760 3

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.
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PMID:Taurine immunoreactivity in the rat supraoptic nucleus: prominent localization in glial cells. 761 71

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.
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PMID:Catecholaminergic innervation of oxytocin neurons in the paraventricular nucleus of the rat hypothalamus as revealed by double-labeling immunoelectron microscopy. 821 44

Male rats were deprived of water for 5 days, and then given water ad libitum for 3, 7, 10 or 14 days. Plasma osmolarity returned to normal in less than 3 days, while pituitary vasopressin (AVP) and oxytocin (OXT) only returned to control levels after 14 days. Sections of the supraoptic nucleus (SON) were hybridized with 35S-labelled cDNA (OXT) or oligonucleotide (AVP) probes. Relative AVP and OXT mRNA contents were quantitated by counting the number of silver grains on a large standard area of the SON, then extrapolating this value to the volume of the whole SON (deduced from surface areas of all the sections). Dehydration significantly enlarged the volume of the SON (x 1.54) and increased the AVP and OXT mRNAcontent (x 2). During rehydration, both SON volume and density of silver grains were higher than normal for at least 7-10 days, although levels started to fall by day 3. The distribution of individual cells according to their silver grain densities remained unimodal during the dehydration-rehydration sequence with an extension, then a return to normal of the distribution range. Maximum sizes of AVP and OXT mRNAs on Northern blots of RNAs extracted from 5 pooled SONs were observed on dehydration day 5. The size of these species fell progressively, reaching control values by rehydration day 14. We conclude that during rehydration, at a time when most of the putative inducers of gene transcription are no longer activated, the peptidergic deficit was accompanied by an increased level of AVP and OXT mRNAs.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Alterations in vasopressin and oxytocin messenger RNA in the rat supraoptic nucleus during dehydration-rehydration evaluated by in situ hybridization and northern blotting. 847 92

In Brattleboro rats, exogenous vasopressin (VP) mRNA can be accumulated, transported, and translated by magnocellular neurons. To determine whether this phenomenon may also occur in magnocellular neurons of normal rats, dispersed hypothalamic neuronal cultures of fetal Sprague-Dawley rats were exposed to VP mRNA. The cultures were maintained in either control medium or medium containing the cAMP elevating drugs, IBMX (3-isobutyl-1-methylxanthine), and forskolin for 23 or 30 days of culture to induce VP synthesis and secretion. Following removal of the IBMX and forskolin at Day 23, VP secretion into the medium declined to baseline by 30 days in vitro, but administration of VP mRNA to these cultures on Day 30 resulted in a 5-fold increase in VP content of the medium (P = 0.005) after 6 h and a 2.5-fold increase after 24 h (P = 0.002). Administration of VP mRNA to the cultures treated continuously with IBMX and forskolin also resulted in a small increase in VP secretion which did not reach significance after either 6 or 24 h. When cultures prepared with continuous I/F were exposed to antisense VP mRNA, VP secretion into the media was decreased by 58%, and VP immunoreactive perikayra were difficult to observe. This demonstrates that the increase in VP release observed after the addition of sense VPmRNA did not reflect a nonspecific effect of the addition of mRNA to the culture medium. Autoradiography of cultures administered 3H- or 32P-VP mRNA for 24 h revealed silver grains associated with varicosities, perikarya, and neuritic processes of neurophysin (NP)-positive, but not NP-negative neurons. These results suggest that exogenously administered mRNA has access to cell translation systems in cultured hypothalamic neurons as well as magnocellular neurons of Brattleboro rats.
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PMID:Increased vasopressin secretion from hypothalamic cultures following administration of exogenous vasopressin mRNA. 881 49

Chromogranin A (CGA) is a calcium-binding glycoprotein thought to be the precursor of several peptides with defined biological activity. Chromogranin A has been localized in most endocrine cells and many neurons in the CNS. Here we studied its expression in neurons of the hypothalamo-neurohypophysial system, which secrete the neurohormones oxytocin and vasopressin. Light and electron microscopic immunocytochemistry and immunoblot analysis with antibodies specific for CGA revealed high levels of chromogranin A immunoreactivity throughout the hypothalamo-neurohypophysial system. In the supraoptic and paraventricular nuclei, it was characterized by intracytoplasmic labelling of magnocellular somata and processes and of certain astrocytes. Extensive labelling of fibres and dilatations characterized the internal layer of the median eminence and the neurohypophysis, transit and terminal site of the neurosecretory axons, respectively. Tanycyte-like cells in the median eminence also displayed reaction. Simultaneous immunofluorescence showed that oxytocinergic and vaso-pressinergic neurons contain chromogranin A. Electron microscopy revealed that chromogranin A immunoreactivity (visualized by pre-embedding immunoperoxidase or silver-enhanced colloidal gold techniques) was associated with neuro-secretory granules in hypothalamo-neurohypophysial system neurons. In astrocytes and pituicytes, it was seen over the cytoplasm and glial filaments. In tissue from colchicine-treated or immobilization-stressed rats, it was clear that chromogranin A immunoreactivity in the hypothalamus was confined to the hypothalamo-neurohypophysial system. In rats in which neurohypophysial secretion was strongly stimulated by dehydration, immunocytochemistry showed that hypothalamo-neurohypophysial system immunoreactivity significantly increased in the magnocellular nuclei but decreased in the neurohypophysis. On the other hand, chromogranin A distribution was not markedly affected by stress or lactation. These observations demonstrate that chromogranin A is present in neurons and, to a lesser degree, glial cells of the hypothalamo-neurohypophysial system and that its expression is closely related to that of the neurohypophysial peptides.
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PMID:Immunocytochemical localization of chromogranin A in the normal and stimulated hypothalamo-neurohypophysial system of the rat. 886 41

Recent studies indicate that calcium binding proteins may play a role in determining the electrical firing patterns of the hypothalamic magnocellular oxytocin (OT) and vasopressin (VP) neurons. In this study we have examined the calbindin-D28k mRNA content of magnocellular neurons in the supraoptic (SON) and paraventricular (PVN) nuclei and determined whether changes in expression correlate with the specific patterns of electrical activity displayed by these cells under different physiological circumstances. In situ hybridization with [35S]-labelled oligonucleotides revealed a heterogeneous pattern of calbindin-D28k mRNA expression in the SON and magnocellular PVN. Quantitative analysis demonstrated that the number of silver grains/cell in the dorsal half of the SON was approximately 30% higher (P < 0.05) than that of the ventral half of the nucleus. Within the PVN, calbindin-D28k mRNA-expressing neurons were detected in the medial magnocellular division of the PVN but not in magnocellular cells forming the core of the lateral magnocellular division. Dehydration for 24 h did not alter calbindin-D28k mRNA expression in the SON, PVN or cingulate cortex. In parturient and lactating rats, calbindin-D28k mRNA levels were significantly (P < 0.05) reduced in the medial magnocellular division of the PVN compared with virgin animals. No significant differences in calbindin-D28k mRNA expression were observed in either ventral or dorsal halves of the SON, or in the cingulate cortex of these animals. These results provide evidence for the differential expression of calbindin-D28k mRNA by hypothalamic magnocellular neurons and suggest that OT cells may express more calbindin-D28k mRNA than VP neurons. The reduction in calbindin-D28k mRNA expression by putative OT neurons of the PVN at the time of parturition and lactation supports the hypothesis of Li and colleagues (J. Physiol., 488 (1995) 601-608) that calbindin may play a part in determining the electrical firing patterns of magnocellular neurons. However, the absence of any similar decrease in the SON suggests that changes in calbindin-D28k mRNA expression are not essential for OT neurons to exhibit episodic bursting behavior.
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PMID:Calbindin-D28k mRNA expression in magnocellular hypothalamic neurons of female rats during parturition, lactation and following dehydration. 901 84

We measured expression of the oxytocin gene in the supraoptic nucleus (SON) during pregnancy, parturition and lactation to examine its relationship to states of accumulation or depletion of oxytocin stores and to conditions of strong excitation of oxytocin neurons. The primary transcript (heterogeneous nuclear RNA, hnRNA) of the oxytocin gene was measured using a 3H-cDNA probe against intron 1 for in situ hybridisation. Autoradiographs of the SON showed the hnRNA as discrete clumps of silver grains within the nucleus of each neuron. The number of cells expressing oxytocin hnRNA did not change during pregnancy but increased during parturition; 10-day lactating animals showed similar increases. Oxytocin mRNA was also measured by in situ hybridisation using a 3H- or 35S-labelled oligonucleotide probe against exon C: hybridisation was seen over the cytoplasm of supraoptic neurons, but no differences were measured between virgin, mid-pregnant, preparturient, parturient or 2-day lactating rats. The data suggest that enhanced oxytocin gene transcription is not necessary to increase oxytocin stores in pregnancy. However, acute stimulation of magnocellular oxytocin neurons at parturition, which strongly increases neuron activity and secretion, results in a rapid increase in the number of cells expressing oxytocin hnRNA, and increased expression is sustained in lactation.
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PMID:Stimulation of expression of the oxytocin gene in rat supraoptic neurons at parturition. 951 60

We present a Raman and surface-enhanced Raman scattering (SERS) study of the following proteins containing S-S group(s): alpha chymotrypsin (alpha-CHT), insulin, lysozyme, oxytocin (OXT), Streptomyces subtilisin inhibitor (SSI), and trypsin inhibitor (STI). The SERS study is performed in order to understand the adsorption mechanism of the above-mentioned proteins on a colloidal silver surface. The SERS spectra presented here show bands associated mainly with aromatic amino acid vibrations. In addition, two distinct vibrations of the -C-S-S-C- fragment are observed in the Raman and SERS spectra, i.e., nu(SS) and nu(CS). The enhancement of the nu(SS) vibration in the SERS spectra yields evidence that the intact disulfide bridge(s) is (are) located near the silver surface. This finding is supported by the presence of the nu(CS) mode(s). The presence of nus(COO-) and nu(C-COO-) in the SERS spectra in the 1384-1399 cm(-1) and 909-939 cm(-1) regions, respectively, indicate that the negatively charged COO- groups (aspartic and glutamic acids) assist in the binding on the positively charged silver surface. The Raman amide I and III bands observed in the 1621-1633 and 1261-1289 cm(-1) ranges, respectively, indicate that the alpha-helical conformation is favored for binding to the surface over the random coil or beta-sheet conformations. In addition, the presence of the imino group of Trp and/or His indicates that these amino acid residues may also bind to the silver sol.
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PMID:Adsorption of S-S containing proteins on a colloidal silver surface studied by surface-enhanced Raman spectroscopy. 1552 14


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