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

Various cytophysiological aspects of the pars intermedia of the pituitary are discussed. Cells containing melanocyte-stimulating hormone (MSH) have been studied under normal and experimental conditions. They react to variations in ionic equilibrium, but without any clear correlation with natraemia and osmotic blood pressure. The MSH-cell stimulation in hypernatraemic mice, which is not inhibited by bromocriptine, seems more specific than the stimulation in hyponatraemic mice, which is blocked by bromocriptine. The existence of a corticotropic cell system has been clearly demonstrated in the mouse (where it is particularly obvious), in the rat and in the cat but its significance is not clear. Although very poorly vascularized, the pars intermedia is rapidly invaded by tracer protein (horseradish peroxidase) injected either intravenously or intracerebroventricularly. The hypophysial cleft rapidly stores the tracer which can be resorbed by macrophagic epithelial cells lying free in the colloid contained in the cleft. Horseradish peroxidase lingers in the pars intermedia but is rapidly eliminated from the other hypophysial lobes after intraventricular (third ventricle) injection. Diffuse innervation of the pars intermedia applies to both glandular (MSH and ACTH) and non-glandular (epithelial and stellate) cells. While aminergic innervation of the pars intermedia is obvious, cholinergic innervation has not been demonstrated ultrastructurally or histochemically. Peptidergic fibres only occasionally penetrate marginal areas of the pars intermedia and seldom establish synaptic contacts with glandular cells. A specific relationship might exist between the pars intermedia and oxytocin fibres in view of the marginal distribution of the latter in the neural lobe. Numerous stellate cells of the pars intermedia react intensely with antiserum to gliofibrillar acid protein, indicating their astrocyte nature, which reinforces the idea of an analogy between the folliculo-stellate system of the hypophysis and the glial cells.
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PMID:Fine structure and cytochemistry of the mammalian pars intermedia. 626 74

Horseradish peroxidase (HRP), injected into the rat caudal medulla oblongata, was detected by immunoperoxidase staining in 120 microns frozen sections, allowing examination of both the distribution and morphology of transporting neurons. In the hypothalamus, several groups of HRP-labeled neurons could be distinguished on the basis of location of the neurons, neural cell size and morphology of the neural processes. Most HRP-labeled neurons were found in the posterior half of the hypothalamus, although scattered single neurons were present as far rostral as the anterior hypothalamus and preoptic area. Prominent groups of HRP-labeled neurons were found in the paraventricular, dorsomedial and arcuate nuclei, near the fornix at two separate levels, and in the lateral posterior hypothalamus. Based on comparison with peptide immunohistochemistry it seems likely that many magnocellular oxytocin, vasopressin and neurophysin neurons in the paraventricular nucleus, and a few ACTH/beta-endorphin neurons in the arcuate nucleus may project to the caudal medulla oblongata.
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PMID:Hypothalamic neurons projecting to the rat caudal medulla oblongata, examined by immunoperoxidase staining of retrogradely transported horseradish peroxidase. 630

The magnocellular neurones of the supraoptic nucleus which synthesize and secrete vasopressin and oxytocin have been commonly regarded as simple "output" neurones in that they receive an input, generate an action potential and in turn release hormone from their terminals in the posterior pituitary. Three lines of evidence are presented which suggest that rat supraoptic nucleus neurons also have axon collaterals which terminate in the hypothalamus close to the nucleus. Small injections of horseradish peroxidase were made directly into the nucleus in hypothalamic slices, allowing visualization of the axons of supraoptic neurones. Collaterals of these axons could be observed in regions both dorsal and dorsolateral to the supraoptic nucleus. In a separate series of experiments, sections of perfusion-fixed hypothalamus were stained for vasopressin and oxytocin using specific antisera. Peptide-containing collaterals of both types were observed near the supraoptic nucleus, in a region similar to that seen after horseradish peroxidase injections. Finally, electrophysiological studies were carried out on hypothalamic slices containing the supraoptic nucleus. A small concentric bipolar stimulating electrode was placed directly into the nucleus and activity of lateral hypothalamic neurones within 0.1-1 mm of the nucleus was recorded. Of 68 neurones studied, 52 were excited by supraoptic stimulation via a synaptic pathway that could be blocked by Ca2+ -free solutions containing 18 mM Mg2+. These studies suggest that supraoptic neurones communicate via axon collaterals with other neurones in the lateral hypothalamus, in addition to their previously well characterised functional role in neurosecretion.
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PMID:Axon collaterals of supraoptic neurones: anatomical and electrophysiological evidence for their existence in the lateral hypothalamus. 632 27

Comparative ultrastructural localization of corticotropin-releasing factor (CRF) and oxytocin was performed in the rat median eminence of Long Evans and Brattleboro rats. The peroxidase-antiperoxidase technique used on serial ultrathin sections revealed CRF and oxytocin neurosecretory granule colocalization in the same fibers of the internal layer running towards the posterior pituitary. It is probable that both these peptides coexist in the same granules. In the Brattleboro rats, while genetically lacking vasopressin, CRF was nevertheless shown to be present. In these rats, as was demonstrated in the Long Evans rats, CRF distribution paralleled that of oxytocin only in the internal zone of the median eminence.
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PMID:Comparative immunoelectron microscopic localization of corticotropin-releasing factor (CRF-41) and oxytocin in the rat median eminence. 633 45

The distribution of vasopressin-, oxytocin- and LHRH-containing nerve fibers in the pineal organ of the dog was demonstrated by use of the peroxidase-antiperoxidase immunohistochemical technique. These neuropeptide-containing fibers penetrated through the pineal stalk from the brain, mainly from the posterior commissural region, into the pineal organ. The vasopressin fibers were the most prominent in number, oxytocin fibers and LHRH fibers were the least. Most of these fibers were found in the proximal part of the pineal organ, but some of them were also observed in the distal part. These peptidergic fibers were distributed not only in the perivascular spaces but among the parenchymal cells.
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PMID:Immunohistochemical studies on the peptidergic nerve fibers in the pineal organ of the dog. 635 38

The presence of neurophysin, oxytocin and vasopressin in the bovine corpus luteum was examined immunocytochemically. Tissue blocks of corpora lutea from pregnant and non-pregnant animals were fixed with glutaraldehyde/paraformaldehyde fixative and immunostained by the peroxidase-antiperoxidase (PAP) method. The simultaneous presence of immunoreactive oxytocin and immunoreactive oxytocin-neurophysin was demonstrated in large luteal cells of non-pregnant animals, while no staining for vasopressin or vasopressin-neurophysin was observed. None of the peptides were detected in the corpus luteum of pregnant animals. The small luteal cells were not found to be stainable at any time.
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PMID:Immunocytochemical evidence for the presence of oxytocin and neurophysin in the large cells of the bovine corpus luteum. 638 23

Neural elements immunoreactive for ovine corticotropin releasing factor-like immunoreactivity (oCRF-LI) were shown to be present in the diencephalon of the pigeon by using peroxidase-antiperoxidase immunocytochemistry. The external zone of the anterior median eminence contains a rich network of varicose oCRF-LI fibers in close proximity to the pituitary portal capillaries. Perikarya reactive for oCRF-LI were found in several regions known to innervate the median eminence and gave rise to axons which joined the hypothalamo-hypophyseal tract. A close topographical relationship between neurophysin-containing and oCRF-LI-containing neurons was found in anterior periventricular regions. These observations suggest that oCRF-LI material might be involved in the hypothalmic control of anterior pituitary hormone secretion in birds, and that neurophysin- and oCRF-LI-producing nerve cells might be functionally coupled.
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PMID:Comparative localization of neurons containing ovine corticotropin releasing factor (CRF)-like and neurophysin-like immunoreactivity in the diencephalon of the pigeon (Columba livia domestica). 638 81

The axonal projections of cell groups containing the most dense collections of steroid hormone concentrating cells have been demonstrated with retrograde neuroanatomical tracing methods. Horseradish peroxidase revealed large numbers of neurons in ventrolateral ventromedial nucleus (VL-VM) which project to dorsal midbrain. Wheat germ agglutinin (immunocytochemical recognition method) revealed large numbers of neurons in medial basal hypothalamus (MBH) and particular subdivisions of paraventricular nucleus (PVN) that project to dorsal caudal medulla or spinal cord. Fluorescent dyes revealed that many preoptic area (POA), anterior hypothalamic (AHA), and bed nucleus of the stria terminalis (BNST) neurons project to ventral tegmental area of Tsai (VTA). Also many neurons in POA and BNST project to amygdala. A method which enabled simultaneous demonstration of the steroid binding capacity and axonal projections of neurons in the same tissue section revealed that 26-36% estradiol (E2) concentrating cells in VL-VM project to dorsal midbrain. E2 concentrating neurons in POA and BNST project to amygdala and E2 concentrating POA neurons project to VTA. These neurons, which send their axons to cell groups located in different brain regions, are probably under the genomic-regulatory influence of E2. Using a method which allows simultaneous demonstration of peptide content and steroid hormone concentrating capacity of cells, many oxytocin-neurophysin and vasopressin-neurophysin containing magnocellular neurons in the caudal PVN were found to concentrate E2. About 4% of the beta-endorphin and about 6% of the dynorphin containing neurons in the MBH concentrate E2. In contrast, virtually none (less than 0.2%) of the LHRH containing hypothalamic neurons concentrate E2.
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PMID:Axonal projections and peptide content of steroid hormone concentrating neurons. 638 52

The oxytocin and vasopressin nerve fibers in the intra- and extrahypothalamic neuronal systems of several mammalian brains are immunohistochemically demonstrated using a modified peroxidase-antiperoxidase technique. The axonal processes of these peptidergic neurons are classified into thick and thin beaded fibers. Thick beaded fibers were preferentially distributed in the hypothalamo-neurohypophysial tract and in some circumventricular organs, with termination on the blood vessels. Thin beaded fibers were found in various extrahypothalamic areas and these terminals were in the vicinity of the neuronal somata of such areas. This report suggests that there are at least two different functions concerning neurotransmission in the oxytocin and vasopressin neuronal system.
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PMID:Two types of oxytocin and vasopressin nerve fibers in the intra- and extrahypothalamic neuronal systems as revealed by immunohistochemistry. 641 Jun 70

The development of two monoclonal antibodies for use as second antibodies in immunocytochemistry is described. The antibodies are produced by mouse X mouse hybrid myelomas, and are both of the IgG type. The two antibodies, RB23 and ND13, were used to detect neurophysin by three-step peroxidase-antiperoxidase (PAP) immunostaining, and were "internally labeled" with 3H-lysine for the radioimmunocytochemical localization of neurophysin, substance P, and tyrosine hydroxylase using rabbit first antibodies. The binding sites of RB23 and ND13 on the rabbit IgG antibodies were determined by solid-phase radioimmunoassay, using allotype-specific rabbit serum to compete with RB23 and ND13. It was found that both RB23 and ND13 are directed against the B4 kappa-light-chain allotype. The immunocytochemical localization of adrenocorticotropic hormone and somatostatin with rabbit primary antibodies was not achieved with RB23 or ND13, and it is proposed that these antibodies are not of the B4 allotype. The findings demonstrate that monoclonal second antibodies can be useful general reagents for conventional immunocytochemistry as well as for radioimmunocytochemistry. Furthermore, allotype-specific monoclonal second antibodies may prove useful in the simultaneous immunohistochemical localization of more than one antigen in a given tissue section.
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PMID:Immunocytochemistry with monoclonal anti-immunoglobulin as a developing reagent: application to immunoperoxidase staining and radioimmunocytochemistry. 641 91


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