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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 332 (1986), S. 79-88 
    ISSN: 1432-1912
    Keywords: Apamin ; Enteric inhibitory neurons ; Intestinal reflexes ; Vasoactive intestinal peptide ; Adenosine triphosphate ; Neurotransmitters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Eight smooth muscle preparations from the stomach, small intestine and large intestine of the guinea-pig were used to compare apamin's actions in reducing the effectiveness of transmission from enteric inhibitory nerves and in reducing responses to inhibitory agonists α,β-methylene ATP, VIP and isoprenaline. The effects of apamin on inhibitory reflexes in the ileum and colon were also evaluated. Apamin had little or no effect on responses to VIP and isoprenaline in any region, but consistently and substantially reduced responses to α,β-methylene ATP. Responses to stimulation of enteric inhibitory neurons were substantially reduced by apamin in the antrum circular muscle, ileum longitudinal and circular muscle, taenia coli and distal colon longitudinal muscle, but it was ineffective in the fundus circular muscle, proximal colon longitudinal muscle and distal colon circular muscle. It caused a small reduction of the relaxation of the ileal circular muscle caused reflexly by distension, but did not modify the similar descending inhibitory reflex in the circular muscle of the colon. It is concluded that apamin can be used to distinguish two types of non-noradrenergic transmission from enteric inhibitory nerves to gastrointestinal muscle. Furthermore, neither VIP nor ATP can be the sole transmitter chemical released from enteric inhibitory neurons throughout the gastrointestinal tract.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 333 (1986), S. 393-399 
    ISSN: 1432-1912
    Keywords: Enteric neurons ; Mucosal transport ; Noradrenaline ; Somatostatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Noradrenaline (NA) and somatostatin (SOM) stimulate intestinal water and ion absorption and are found in mucosal nerve fibres and nerve terminals in submucous ganglia of the guinea-pig small intestine. As the main projection of submucous neurons is to the mucosa, NA and SOM might alter mucosal transport either by a direct effect on the epithelium or indirectly, by affecting submucous neurons. In this study these two possible sites of action of NA and SOM have been investigated in mucosa-submucosa preparations of guinea-pig ileum. In addition, the actions of NA and SOM on the secretory responses caused by stimulation of different populations of submucous neurons have been studied. The stimulants of secretion used were a nicotinic agonist, 1,1-dimethyl-4-phenylpiperazinium (DMPP, 10−5 M), 5-hydroxytryptamine (5-HT, 10−7 M) and electrical field stimulation (EFS), which activate cholinergic, noncholinergic and mixed populations of submucous secretomotor neurons, respectively. Segments of intestine were dissected free of external muscle and myenteric plexus and mounted in Ussing chambers. Short-circuit current (I sc) was measured as an indication of net active ion transport across the tissue. NA (≥10−8 M) and SOM (〉10−10 M) each caused a decrease in I sc, indicating a net increase in ion absorption. The NA response was abolished and the magnitude of the SOM response was reduced to 20% by tetrodotoxin (10−7 M). DMPP, 5-HT and EFS each stimulated nerves that increased I sc and each of these responses was significantly diminished by NA and SOM; for both NA and SOM the decrease in the DMPP response was significantly greater than the decrease observed in the response to carbachol (10−6 M). Phentolamine (10−6 M) abolished all of the effects of NA but caused no change in the SOM effects. These studies have shown that NA and SOM cause similar changes in net ion transport, that their actions are primarily on submucous secretomotor neurons and that NA and SOM can diminish the responses to stimulation of both cholinergic and noncholinergic submucous neurons. In this tissue it is also known that SOM coexists with NA in noradrenergic nerve terminals in the submucosa. However, when applied together, NA and SOM caused no greater decrement in the carbachol and 5-HT responses than would be predicted by adding the separate effects of NA and SOM. Hence there was no obvious interaction between NA and SOM effects on mucosal transport.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0878
    Keywords: Perivascular nerves ; Cardiac innervation ; Neuropeptides ; Neuropeptide Y ; Substance P ; Adrenergic nerves ; Amphibia, Anura (Bufo marinus)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The innervation of the major arteries and heart of the toad (Bufo marinus) was examined by use of glyoxylic acid-induced catecholamine fluorescence and peptide immunohistochemistry. All arteries possessed a moderate to dense plexus of adrenergic axons, which also showed neuropeptide Y-like immunoreactivity (NPY-LI). Some adrenergic axons in the intracardiac vagal trunks showed NPY-LI, but the varicose adrenergic axons innervating the cardiac muscle of the atria and ventricle, and the coronary blood vessels did not display NPY-LI. About half of the nerve cell bodies in the anterior sympathetic chain ganglia with dopamine-β-hydroxylase-LI (DBH-LI) also contained NPY-LI. The nerve cell bodies with DBH-LI alone were generally larger (median diameter 30 μm) than those with both DBH-LI and NPY-LI (median diameter 20 μm). Some cell bodies showing DBH-LI alone were surrounded by boutons with NPY-LI but not DBH-LI. Axons that displayed simultaneously both substance P-LI (SP-LI) and calcitonin gene-related peptide-LI (CGRP-LI) also formed a plexus around all arteries studied, being particularly dense around the mesenteric and pulmonary arteries. These axons are most likely sensory since SP-LI was reduced by capsaicin treatment, and nerve cell bodies with both SP-LI and CGRP-LI were found in dorsal root ganglia and the vagal ganglion. A dense plexus of axons showing somatostatin-LI was located around the pulmonary artery and its main intrapulmonary branches. A few nerves with vasoactive intestinal polypeptide-LI were found around the dorsal aorta and pulmonary artery. No perivascular nerves with enkephalin-LI were observed. Reversed-phase, high-pressure liquid chromatography of acid extracts of the large arteries showed that the major peaks of NPY-LI and SP-LI coeluted with porcine NPY (1–36) and synthetic SP (1–11), respectively. Thus, the location and structure of these peptides in perivascular nerves has been highly conserved during vertebrate evolution.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 244 (1986), S. 173-180 
    ISSN: 1432-0878
    Keywords: Autonomic ganglia ; Coeliac ganglion ; Vascular innervation ; Intestinal innervation ; Neuropeptides ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distributions within the coeliac ganglion of different chemically coded subgroups of noradrenaline neurons, and the relationships between these neurons and nerve fibres projecting to the ganglion from the intestine, have been assessed quantitatively by use of an immunohistochemical double-staining method. Noradrenaline (NA) neurons made up 99% of all cell bodies. Of these, 21% were also reactive for somatostatin (NA/SOM neurons), 53% were also reactive for NPY (NA/NPY neurons), and 26% were not reactive for either peptide. NA neurons without reactivity for any of the peptides whose localization was tested have been designated NA/-. A small percentage, about 1%, of neurons were reactive for both NPY and SOM. The three major types of NA neurons were arranged in clumps or ribbons throughout the ganglia, with a tendency for NA/SOM neurons to be medial and NA/NPY neurons to be lateral in the ganglia. A small group of neurons (〈1%) encoded with dynorphin, NPY and vasoactive intestinal peptide (VIP) was encountered. VIP-immunoreactive nerve terminals, projecting to the ganglion from cell bodies in the intestine, ended around NA/SOM and NA/neurons but not around NA/NPY neurons. Thus, the VIP axons from the intestine end selectively around neurons that modify intestinal function (NA/SOM and NA/-neurons) but not around neurons, the terminals of which supply blood vessels (NA/NPY neurons).
    Type of Medium: Electronic Resource
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