Regulatory peptide receptors: Visualization by autoradiography. In: Polak JM, editor. Regulatory Peptides. Basel: Birkhäuser; 1989. pp. 70-97. [DOI: 10.1007/978-3-0348-9136-3_5]

The dorsal vagal complex of the ferret: anatomical and immunohistochemical studies

To further the understanding of gastrointestinal function in this species, and in particular to advance our own work concerning central emetic pathways, the cytoarchitecture and the distribution of eight neurochemicals were studied in the ferret dorsal vagal complex (DVC; area postrema, nucleus of the solitary tract [nTS] and dorsal motor nucleus of the vagus). The cytoarchitectural features of this region in the ferret were similar to those seen in other species; however, the ferret possesses a particularly large and distinct subnucleus gelatinosus of the nTS. Dense calcitonin gene-related peptide-immunoreactivity was found in the gelatinous, interstitial and commissural subnuclei of the nTS, with lesser amounts in other regions of the DVC. Enkephalin-immunoreactivity of varying densities was found throughout the DVC. Moderate to dense galanin-immunoreactivity was observed throughout the DVC, with the exception of the subnucleus gelatinosus of the nTS, from which it was virtually absent. Dense neuropeptide Y-immunoreactivity was observed in the subnucleus gelatinosus and interstitial subnucleus, with moderate staining in other regions of the DVC. Neurotensin immunoreactivity was very sparse or absent. Immunoreactivity for serotonin was sparsely distributed throughout the DVC. Moderate somatostatin-immunoreactivity was observed over a large portion of the DVC, but was virtually absent from the gelatinosus and interstitial subnuclei. Substance P immunoreactivity was observed throughout the DVC and was particularly dense in the dorsal/dorsolateral subnucleus and the dorsal aspects of the medial and commissural subnuclei. In terms of its cytoarchitecture the DVC of the ferret is more similar to the cat than the rat, especially with regard to the area postrema and the subnucleus gelatinosus of the nTS. The distribution of neuroactive substances was largely similar to other species; however, differences were present particularly in patterns of immunoreactivity for enkephalin, serotonin, neuropeptide Y and somatostatin.

Localization and characterization of neuropeptide Y binding sites in porcine and human colon

1. We have used quantitative receptor autoradiography to investigate the localization and characteristics of binding sites for 125Iodine-Bolton Hunter-labelled human neuropeptide Y ([125I]-BH-NPY) in porcine and human colon, and compared the binding characteristics with those found in porcine spleen. 2. Saturable, specific, high affinity [125I]-BH-NPY binding was localized to myenteric ganglia in porcine and human colons, and to submucosal ganglia in porcine colon. 3. Specific [125I]-BH-NPY binding to porcine myenteric ganglia was reversible in the presence of guanosine 5'-O-(3-thiotriphosphate) and was inhibited by related peptides with the rank order of potency; porcine NPY = human NPY = peptide tyrosine tyrosine (PYY) >> pancreatic polypeptide. 4. The Y2 selective analogue, NPY (13-36), competed for [125I]-BH-NPY binding to porcine myenteric ganglia with greater potency than the Y1 selective analogue, [Leu31, Pro34] NPY, the difference being small, but significant. 5. The characteristics of [125I]-BH-NPY binding to porcine myenteric ganglia were similar to those observed concurrently to porcine splenic red pulp. 6. The small difference in inhibitory potencies between NPY(13-36) and [Leu31, Pro34]NPY observed in this study in comparison with previous studies was not explained by differential ligand depletion during incubations, but may be due to differences in methodology between binding studies performed on tissue sections and on membranes. 7. We conclude that specific [25I]-BH-NPY binding sites are present in the myenteric and submucosal ganglia of the colon and that these sites may act as functional receptors by which NPY and PYY modulate colonic motility and electrolyte transport.

Somatostatin-binding sites on rat telencephalic astrocytes. Light- and electron-microscopic studies in vitro and in vivo

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.