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  • 1
    Electronic Resource
    Electronic Resource
    Binding and internalization of gold-conjugated somatostatin and growth hormone-releasing hormone in cultured rat somatotropes (1989)
    Springer
    Cell & tissue research 258 (1989), S. 309-317 
    Details
    ISSN: 1432-0878
    Keywords: Somatotropes, growth hormone cells ; Immunocytochemistry ; Growth hormone (GH) ; Receptors, membrane ; Somatostatin (SRIF) ; Growth hormone-releasing hormone (GRH) ; Rat (Han: WIST)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The synthetic peptides somatostatin (SRIF) and growth hormone-releasing hormone (GRH) were coupled directly to colloidal gold of different particle sizes. Both conjugates were biologically active in displacing the corresponding radiolabeled hormones from high affinity binding sites in pituitary membranes. Release of growth hormone (GH) from cultured anterior pituitary cells was modulated by both conjugates alone or in combination. Ultrastructural studies were performed with cells incubated at 4° C (2 h) and 37° C (2 min-2 h) with one of the labeled peptides or their combination. Somatotropes were identified by immunostaining with anti-rGH followed by protein A-ferritin, thus obtaining a triple labeling. Both hormone conjugates were internalized in different vesicles in the beginning but accumulated during longer incubation times in the same compartment. The secretory vesicles and the nucleus were not labeled by any hormone conjugate. In contrast to SRIF-gold, the uptake of GRH-gold conjugate decreased with longer incubation times. This effect could be neutralized by simulatenous incubation of the somatotropes with both regulating hormones. Hence, whereas the binding and internalization of SRIF by somatotropes do not seem to be influenced by GRH, the corresponding processes for GRH are stimulated by the presence of SRIF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239451
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  • 2
    Electronic Resource
    Electronic Resource
    Altered pattern of vasopressin distribution in the hypothalamus of rats subjected to immobilization stress (1978)
    Springer
    Cell & tissue research 189 (1978), S. 267-275 
    Details
    ISSN: 1432-0878
    Keywords: Paraventricular nucleus (rat) ; Vasopressin ; Immobilization stress ; CRF-release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Generally, the CRF-like activity of vasopressin is studied in experiments involving adrenalectomy and corticosteroid replacement. In order to avoid this complex type of stress, male and female (diestrus, estrus) rats were exposed for 5min to immobilization stress and sacrificed 5, 15, and 30 min thereafter. After a survival period of 5 min the vasopressin-synthesizing part of the paraventricular nucleus exhibited an increased activity. Vasopressin-reactive axons in the pericapillary layer of the median eminence and among the solid cell clusters of the pars tuberalis became more conspicuous and increased in number. In this group of experimentally treated animals the prechiasmatic division of the supraoptic nucleus did not show any changes in immunoreactivity. The same holds true for the neurohypophyses in all experimental groups. In animals with increased survival times the supraoptic nucleus exhibited a slightly increased activity, whereas the staining intensity of the paraventricular nucleus decreases gradually. From these results it can be concluded that the paraventricular nucleus is involved in the first phase of the stress response. The problem of vasopressin or a very similar peptide synthesized in this nucleus and exerting a CRF-releasing function is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209276
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  • 3
    Electronic Resource
    Electronic Resource
    Immunocytochemical staining of supraoptic neurons from homozygous Brattleboro rats by use of antibodies against two domains of the mutated vasopressin precursor (1986)
    Springer
    Cell & tissue research 244 (1986), S. 351-358 
    Details
    ISSN: 1432-0878
    Keywords: Diabetes insipidus ; Supraoptic nucleus ; Vasopressin ; Vasopressin precursor ; Light- and electron-microscopic immunocytochemistry ; Brattleboro rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary By use of an antibody against the 14 amino acids in the mutated vasopressin precursor (CP-14) characteristic of the homozygous Brattleboro rat, an immunohisto- and-cytochemical study was performed on the supraoptic nuclei of homozygous Brattleboro rats. At the light-microscopic level, varying numbers of perikarya per section exhibited a positive reaction. The most intense staining was observed in a patchy manner on the peripheral portions of the cytoplasm, its central portion being stained less intensely. The antiserum did not react with the supraoptic perikarya of the Wistar rat. In the homozygous Brattleboro rat, antibodies against normal vasopressin only rarely resulted in a positive immunoreaction. However, when it was observed, incubation of the subsequent section with CP-14-antiserum suggested a co-localization of both peptides in the same perikaryon. At the ultrastructural level, CP-14 immunoreactivity was demonstrated on the secretory cisternae of the Golgi apparatus, on lysosome-like bodies and on parts of the rough endoplasmic reticulum. With the use of an antibody against normal vasopressin, immunoreactivity was confined to very limited areas of the rough endoplasmic reticulum. The oxytocin immunoreactivity in supraoptic perikarya of Brattleboro rats did not differ from that in the Wistar rat, either at the light- or at the electron-microscopic levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219211
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  • 4
    Electronic Resource
    Electronic Resource
    Somatostatin-binding sites on rat telencephalic astrocytes (1990)
    Springer
    Cell & tissue research 262 (1990), S. 431-443 
    Details
    ISSN: 1432-0878
    Keywords: Astrocytes ; Telencephalon ; Receptors, membrane ; Somatostatin (SRIF) ; Rat (Han: WIST)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using a somatostatin-gold conjugate as ligand, high-affinity binding sites for this neuropeptide were demonstrated at three levels: (i) cultured astrocytes from rat cortex, (ii) hippocampal slice cultures, and (iii) frozen tissue sections of rat telencephalon. The conjugate proved as active as the native peptide in competing for the binding sites. Light-microscopic visualization of bound ligand was achieved by silver intensification of the colloidal gold. This method is faster and yields superior resolution compared with autoradiography. Cultured astrocytes from cortex and hippocampus could be labeled by the ligand. At the light- and electron-microscopic level, astrocytes could be double-labeled by the somatostatin-gold conjugate and immunostaining for glial fibrillary acidic protein (GFAP). In hippocampal slice cultures, the conjugate did not penetrate into the neuropil because of a covering glial layer. However, a portion of this completely GFAP-positive covering glia reacted with the somatostatin ligand. In frozen brain sections, apart from delicate punctate structures, two types of labeled glia cells were seen: single stellate astrocytes and perivascular glia cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305240
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  • 5
    Electronic Resource
    Electronic Resource
    Somatostatin binding sites on rat diencephalic astrocytes (1991)
    Springer
    Cell & tissue research 263 (1991), S. 253-263 
    Details
    ISSN: 1432-0878
    Keywords: Astrocytes ; Diencephalon ; Receptors, membrane ; Somatostatin (SRIF) ; Rat (Han: Wist)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using a somatostatin-gold conjugate of known biological activity, high affinity binding sites for this neuropeptide were visualized at cellular resolution on cultured diencephalic astrocytes and on frozen sections of the rat diencephalon. Binding could be completely suppressed in competition experiments with surplus unlabeled somatostatin. On sections, the ligand was displaced from its binding sites by 10 μM guanosine triphosphate indicating a functional significance of the labeled structures. As with the native peptide, a surplus of the analog SMS 201–995 suppressed nearly all staining. The ligand was bound to distinct populations of astrocytes, namely to those in subependymal and perivascular positions, to astrocytes in somatostatin-innervated hypothalamic nuclei in the mid-sagittal plane and to borderline regions of circumventricular organs. A general mismatch between the distribution of somatostatin-immunoreactive terminals and the pattern of binding of the ligand does not exist. This, together with the competition experiments, suggests a functional relationship between the somatostatin-releasing neurons and associated astrocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318767
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  • 6
    Electronic Resource
    Electronic Resource
    Light- and electron microscopic localization of vasopressin or a vasopressin-like substance in the neurons of the rat suprachiasmatic nucleus (1978)
    Springer
    Cell & tissue research 194 (1978), S. 361-365 
    Details
    ISSN: 1432-0878
    Keywords: Suprachiasmatic nucleus (rat) ; Vasopressin ; Immunoreactive neurons ; Ultrastructural localization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the suprachiasmatic nucleus of the rat light microscopic immunostaining for vasopressin reveals a distribution pattern of the immunoreactive material different from that known for the supraoptic nucleus. Among non-stained neurons positive-reacting perikarya display a cap- or tiplike labeling. The area of the suprachiasmatic nucleus is marked by delicate vasopressin-positive fibers. At the ultrastructural level the reaction product, after incubation with anti-vasopressin, is localized in small elementary granules unevenly distributed over the cytoplasm. Groups of axons containing specifically labeled granules contact non-reacting fibers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220402
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  • 7
    Electronic Resource
    Electronic Resource
    Neuroglandular contacts between vasopressin-reactive fibers and cells of the pars tuberalis in the rat (1979)
    Springer
    Cell & tissue research 196 (1979), S. 361-365 
    Details
    ISSN: 1432-0878
    Keywords: Neuroglandular contacts ; Vasopressin ; Pars tuberalis (rat) ; Ultrastructural immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In electron micrographs fibers containing vasopressin-immunoreactive elementary granules 100–120 nm in diameter are observed within the basal lamina of the adenohypophyseal pars tuberalis adjacent to the rostral portion of the median eminence. The concept of a neuroglandular transmitter function of vasopressin is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00240108
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  • 8
    Electronic Resource
    Electronic Resource
    Electronmicroscopic immunocytochemical study on the vasopressin-containing neurons of the thirsting rat (1977)
    Springer
    Cell & tissue research 184 (1977), S. 237-247 
    Details
    ISSN: 1432-0878
    Keywords: Supraoptic neurons (rat) ; Vasopressin ; Thirst ; Electron microscopic immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Whereas in thirsting animals the perikarya of the nucleus supraopticus are nearly empty of neurosecretory granules as evidenced by electron microscopic observation, the perikarya are heavily stained by light microscopic immunohistochemical staining. In an attempt to discover the substrate responsible for the positive immunohistochemical staining in thirsting rats, the neurons of the supraoptic nucleus of normal and long-term thirsting animals were compared by electron microscopic immunocytochemistry (indirect PAP-method). In controls all parts of the vasopressin-synthesizing neuron are filled with elementary granules which render a positive and uniform reaction after immunostaining with the indirect PAP-method. The positively reacting fibers in the external zone of the median eminence contain smaller granules than those of the tractus supraoptico-hypophyseus. Within the nucleus suprachiasmaticus, no positive reaction after immunostaining was found. In long-term thirsting animals PAP-complexes as markers of vasopressin are located over the ergastoplasm and over the few small elementary granules. The processes within the nucleus supraopticus and the ballooned axons in the internal zone of the median eminence exhibit “free”, i.e. non granule-bound, PAP-complexes. Findings in the nucleus suprachiasmaticus and the median eminence of thirsting animals correspond to those in controls. The neurohypophysis is almost completely devoid of PAP-labeled elementary granules. From these results it can be concluded that during thirst vasopressin synthesis is increased in the ergastoplasm and that the hormone is transported partly in a non granule-bound form. Direct contacts between neurosecretory cells and the basal lamina are found more often in thirst-stressed animals and are typical of neurohemal regions. It is discussed whether these neurohemal regions may develop transitionally under stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223071
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