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  • 1
    ISSN: 1432-0878
    Keywords: Neurosecretory granules ; Supraoptic nucleus ; Colchicine ; Oxytocin neurones ; Co-transmission ; Brattleboro rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Magnocellular neurones in the supraoptic nucleus of the homozygous Brattleboro rat, which are unable to produce vasopressin, were investigated by immunocytochemistry to identify both the oxytocin cells and the abnormal neurones, which in normal animals would produce vasopressin. The abnormal cell profiles were significantly more rounded than those of the oxytocin cells. Both cell types showed evidence of hyperactivity, but the Golgi apparatus was more extensive in the oxytocin cells, probably as a result of the failure of the abnormal cells to produce vasopressin and its neurophysin and the resultant reduction in hormone packaging. Neurosecretory granules (NSG) 160 nm in diameter were found in the oxytocin perikarya but were absent from the abnormal cell bodies. In addition, a population of small dense granules (SDG) 100 nm in diameter was observed in both types of neurone, in numbers equal to the NSG in oxytocin cells. Injection of a low, non-lethal dose of the axonal transport inhibitor colchicine resulted in a rapid and equal accumulation of both NSG and SDG in oxytocin perikarya and of SDG in the abnormal perikarya after one day. The effects of colchicine were reversed 2–3 days after administration. The SDG, which may contain a co-transmitter or co-hormone substance, are thus produced at a similar rate to NSG, and appear to be transported from the perikarya for subsequent release at the nerve endings.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0878
    Keywords: Vasopressin ; Vasopressin-neurophysin ; Septum ; Synapse ; Immunoperoxidase cytochemistry ; Immunogold cytochemistry ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Synapses in the lateral septum of the murine brain have been investigated by ultrastructural immunocytochemistry, using monoclonal anti-neurophysins in both immunoperoxidase and immunogold techniques. In the region shown by light microscopy to be rich in vasopressinergic innervation, synaptic boutons containing ∼30 nm clear vesicles and occasional ∼100 nm dense-cored granules (granules) were stained by pre-embedding immunoperoxidase procedures with antisera to vasopressin-neurophysin, but not oxytocin-neurophysin; reaction product was diffusely distributed in the terminals. Terminals were symmetrical, and both axosomatic and axodendritic in type. Postembedding immunogold procedures by use of anti-vasopressin-neurophysin labeled only the ∼100 nm diameter granules in the terminals. Sodium meta-periodate treatment ‘bleached’ immunoreactive granules, indicating the presence of a carbohydrate residue. The quantum of peptide packaged in the granules appears to be smaller than that in magnocellular neurones; nevertheless, the results indicate that, as in the magnocellular neurosecretory system, vasopressin and its neurophysin are packaged exclusively in granules, and that vasopressin in the septum is likely to be derived from a precursor comprising vasopressin, vasopressin-neurophysin and a glycosylated residue.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0878
    Keywords: Hypothalamo-neurohypophysial system ; Supraoptic nucleus ; Neurosecretory granules ; Neurophysins ; Lysosomes ; Immuno-gold techniques ; Double-immunolabeling ; Monoclonal antibodies ; Murids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural post-embedding immuno-gold techniques were applied to the supraoptic nucleus and the neurohypophysis of mice and rats. The primary antibodies were three different monoclonal antineurophysins, used in protein A-gold and immunoglobulin-gold procedures. Conventional plastic embedding as well as hydrophilic media (L.R. White) were used; non-osmicated and osmicated tissues were immunolabeled; sodium metaperiodate oxidation was used, but was not essential for immunolabeling. Vasopressinergic and oxytocinergic NSGs were identified by the specific immunoreactivity of their respective neurophysins on adjacent thin sections, and by sequential double labeling on the same thin section using two different antibodies associated with gold probes of different diameters. The immunoidentification indicates that vasopressin NSGs can additionally be differentiated as larger, with more electron-dense matrix, and susceptible to damage by sodium metaperiodate. The only organelles consistently labeled were neurosecretory granules (NSGs), either intact or within lysosomal configurations. Some lysosomal dense bodies were immunoreactive even when discrete NSGs were no longer morphologically recognisable within them. Labeled NSGs were located within neuronal cell bodies, along axonal shafts and within axonal swellings and endings; occasionally immunoreactive NSGs were observed within synaptic boutons. Labeling intensity was semi-quantitatively gauged by counting gold particles in relation to numbers of NSGs per axonal varicosity. The precise localisation achieved with particulate immunogold labeling surpasses that previously obtained with diffuse electron-dense immunoreaction products.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0878
    Keywords: Key words: Anterior pituitary ; Synapse ; Innervation ; Substance P ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Our previous studies have proved the presence of substantial amounts of peptidergic nerve fibers in the anterior pituitary of human, monkey, dog, and rat, and synaptic contacts have been demonstrated on corticotrophs and somatotrophs in the dog. The present study is aimed at investigating the synaptic relationship between axons and gland cells in the rat. The substance P-like-immunoreactive nerve fibers were studied immuno-electron-microscopically. They were nonmyelinated and varicose. Typical synaptic contacts between the fibers and every type of the hormone-secreting gland cell could be identified, most frequently on lactotrophs. No synaptic contacts were found on the folliculo-stellate cell. The synaptic contacts were of asymmetrical type with clusters of small round clear vesicles at the presynaptic site and scattered large dense-cored vesicles. This pattern of synaptic relationships was markedly different from that in the dog. The presence of synapses in the anterior pituitary of the rat implies a direct neural regulation of certain cells and strongly supports our hypothesis of neural-humoral dual regulation of this gland.
    Type of Medium: Electronic Resource
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