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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 263 (1991), S. 253-263 
    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
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  • 2
    ISSN: 1432-0878
    Keywords: Somatostatin ; Cholecystokinin ; Binding sites ; Receptors ; Neurons ; Telencephalon ; Rat (Han: WIST)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The identification of high-affinity binding sites for neuropeptides on individual target cells is a prerequisite when studying the sites of action and the manner in which peptides act as neuromediators. In situ and in vitro, this can be achieved using newly synthesized, biologically active conjugates of somatostatin or cholecystokinin (sulphated octapeptide) with colloidal gold. Labelled neurons show a peptide-specific, non-overlapping distribution in rat telencephalic structures; i.e, whereas the somatostatin-gold conjugate labels binding sites on neurons and glial cells, cholecystokinin-binding sites are restricted to neurons. Binding of either gold-labelled ligand can be competitively suppressed by excess amounts of the native peptide or its analogues. Neuronal somatostatin-binding sites are visualized on neurons in lamina III and, in particular, in lamina V/VI of the primary somatosensory cortex and in the magnocellular nucleus of the telencephalic cholinergic system. Cholecystokinin-binding sites are localized in the main olfactory bulb, on neurons in the cortical “hindlimb” and “forelimb” region, in the hippocampus, and in the cingulate and visual cortex.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 262 (1990), S. 431-443 
    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
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