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  • Intestine, small  (8)
  • Somatostatin  (6)
  • Guinea-pig ileum  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Effects of noradrenaline and somatostatin on basal and stimulated mucosal ion transport in the guinea-pig small intestine (1986)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 333 (1986), S. 393-399 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00500015
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  • 2
    Electronic Resource
    Electronic Resource
    Branching patterns and projections of enteric neurons containing different putative transmitters
    Amsterdam : Elsevier
    Peptides 2 (1981), S. 119-122 
    Details
    ISSN: 0196-9781
    Keywords: 5-Hydroxytryptamine ; Enteric nervous system ; Immunohistochemistry ; Noradrenaline ; Somatostatin ; Substance P
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0196-9781(81)90022-X
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  • 3
    Electronic Resource
    Electronic Resource
    Inhibitory effects of opioids in a circular muscle-myenteric plexus preparation of guinea-pig ileum (1987)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 336 (1987), S. 419-424 
    Details
    ISSN: 1432-1912
    Keywords: Guinea-pig ileum ; Myenteric plexus ; Circular muscle ; Opioid receptors ; Naloxone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The actions of opioids were examined in a strip preparation of the external muscle and myenteric plexus of the guinea-pig ileum cut parallel to the circular muscle. Contractions of the circular muscle induced by electrical stimulation of myenteric neurons were depressed in a concentration-dependent manner by the mu agonists, morphine and DAGO, and by the kappa agonist, U-50,488H. The concentrations of morphine, DAGO and U-50,488H which depressed nerve-mediated contractions by 50% (IC50) were 86 nM, 11 nM and 5.0 nM, respectively. The equilibrium dissociation constants (K D) for naloxone as an antagonist of the inhibitory effects of DAGO and of U5-0,488H were 5.6 nM and 29.4 nM, respectively. In contrast to the potent inhibitory effects of mu and kappa agonists, the delta-selective agonist, d-Pen-l-Pen, produced only weak inhibition of nerve-mediated contractions. Even at a concentration of 3 μM, there was less than 50% inhibition, which was not antagonised by the delta receptor antagonist, ICI 174864. The experiments indicate that both mu and kappa opioid receptors are present on the myenteric neurons supplying the circular muscle and that delta receptors are either absent or ineffectively activated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00164876
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  • 4
    Electronic Resource
    Electronic Resource
    Opioid mu and kappa receptors on axons of cholinergic excitatory motor neurons supplying the circular muscle of guinea-pig ileum (1988)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 338 (1988), S. 397-400 
    Details
    ISSN: 1432-1912
    Keywords: Guinea-pig ileum ; Circular muscle ; Opioid receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In preparations of guinea-pig ileum comprising the circular muscle and the axonal processes of myenteric neurons, electrical stimulation evoked contractions of the circular muscle which were abolished by tetrodotoxin and by hyoscine, indicating that they resulted from action potential-mediated release of acetylcholine. The selective mu opioid agonist, (d-Ala2-N-Me-Phe4-Gly5-ol)-enkephalin (DAGO), and the selective kappa opioid agonist, trans-(±)-3,4-dichloro-N-(2-(I-pyrrolidinyl) cyclohexyl) benzeneacetamide, U-50488H, caused concentration-dependent and naloxone-reversible inhibitions of nerve-mediated contractions. The experiments indicate that opioid mu and kappa receptors are present on the axonal processes of cholinergic excitatory motor neurons supplying the circular muscle of the guinea-pig ileum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00172116
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  • 5
    Electronic Resource
    Electronic Resource
    Evidence for the release of endogenous substance P from intestinal nerves (1979)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 306 (1979), S. 195-201 
    Details
    ISSN: 1432-1912
    Keywords: Substance P ; Guinea-pig ileum ; Densensitization ; Peptidergic nerves ; Immunofluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The desensitization of receptors for substance P in the longitudinal muscle of the guinea-pig ileum has been studied. Receptors for substance P in the muscle became desensitized in the presence of relatively large concentrations of synthetic substance P; a desensitizing concentration of substance P of 7.5×10−9 M shifted the concentration-response curve for substance P about 20-fold to the right, while a desensitizing concentration of 7.5×10−8 M shifted the curve about 300-fold to the right. This desensitization appeared specific; concentration-response curves for carbachol, DMPP, 5-HT and bradykinin were not significantly affected by substance P, 7.5×10−8 M. Furthermore, substance P in concentrations up to 7.5×10−8 M did not modify transmission from either cholinergic nerves or enteric inhibitory nerves when these were stimulated electrically. However, hyoscine-resistant contractions produced by stimulation of nerves in the ileum at 10 Hz were abolished by exposure to concentrations of substance P of 7.5×10−9 M or greater, suggesting that these nerves release a substance similar to or identical with substance P. DMPP evoked small hyoscine-resistant contractions of the ileum. These contractions were also antagonised by desensitization of receptors for substance P. Immunohistochemical studies showed substance P-like immunoreactivity in nerve terminals of both the myenteric and submucous plexuses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00507103
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  • 6
    Electronic Resource
    Electronic Resource
    Opioid dependence in myenteric neurons innervating the circular muscle of guinea-pig ileum (1989)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 339 (1989), S. 166-172 
    Details
    ISSN: 1432-1912
    Keywords: Guinea-pig ileum ; Myenteric plexus ; Circular muscle ; Opioid dependence ; Morphine withdrawal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Guinea-pigs were treated with morphine for 6–8 days by subcutaneous implantation of pellets, each containing a mixture of morphine base (120 mg) and morphine hydrochloride (35 mg). Each guinea-pig received a single pellet. Mechanical activity of the circular muscle was recorded in vitro in preparations comprising the circular muscle and myenteric plexus. Exposure to morphine was maintained by addition of 1 μM morphine to the organ baths. After 90 min, morphine was withdrawn, either by repeatedly washing tissues in morphine-free Krebs' solution , or by addition of naloxone to reduce the occupancy of the opioid receptors by morphine. Withdrawal of morphine resulted in markedly enhanced contractile activity compared with that in circular muscle-myenteric plexus preparations from untreated control guinea-pigs. The withdrawal contractions were abolished by tetrodotoxin (600 nM) and greatly reduced by hyoscine (1 μM), indicating that they resulted from action potential discharge in myenteric neurons that release acetylcholine onto the circular muscle. Activation of the cholinergic excitatory motor neurons was not secondary to synaptic activation by cholinergic interneurons, because hexamethonium (100 μM) did not affect withdrawal contractions. The withdrawal response may therefore arise in the cholinergic excitatory motor neurons themselves, or in neurons that activate them via noncholinergic mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00165139
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  • 7
    Electronic Resource
    Electronic Resource
    Somatostatin in human enteric nerves (1984)
    Springer
    Cell & tissue research 237 (1984), S. 299-308 
    Details
    ISSN: 1432-0878
    Keywords: Somatostatin ; Somatostatin immunoreactivity ; Somatostatin-containing neurons ; Stomach ; Intestine small ; Intestine, large ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Somatostatin-immunoreactive nerves and endocrine cells were localized by use of immunohistochemistry in human stomach, small and large intestine. The nature of the immunoreactivity in acid extracts of separated layers of intestine was determined with separation by high pressure liquid chromatography followed by detection with radioimmunoassay; authentic somatostatin-14 was found in the external musculature, which contains nerves, and in the submucosa and mucosa, which contain both nerve fibres and endocrine cells. The distribution of somatostatin nerves in the gastric antrum, duodenum, jejunum, ileum, ascending and sigmoid colon, and rectum is described. In the intestine many positive perikarya and fine varicose fibres were seen. Mucosal fibres formed a sub-epithelial plexus and a looser network in the lamina propria; this nerve supply was less dense in the large intestine. Submucous ganglia contained positive perikarya and terminals; many terminals formed pericellular baskets, mainly around non-reactive cells. A small number of nerve fibres were associated with submucosal blood vessels. The innervation of the circular and longitudinal muscle was sparse. Positive nerve terminals were seen in the myenteric plexus, although fewer than in the submucous ganglia; positive perikarya were scarce in myenteric ganglia. Somatostatin-immunoreactive nerves were found in the muscle layers and myenteric plexus of the gastric antrum, but were not detected in the antral mucosa and all layers of the gastric body. The distribution of human enteric somatostatin nerves is compared to that in small laboratory animals, and possible roles for these nerves are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217149
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  • 8
    Electronic Resource
    Electronic Resource
    Choline acetyltransferase- and peptide immunoreactivity of submucous neurons in the small intestine of the guinea-pig (1984)
    Springer
    Cell & tissue research 237 (1984), S. 329-336 
    Details
    ISSN: 1432-0878
    Keywords: Choline acetyltransferase ; Cholecystokinin ; Neuropeptide Y ; Somatostatin ; Substance P ; Intestine, small ; Submucous ganglia ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The peptides cholecystokinin (CCK), neuropeptide Y (NPY), somatostatin (SOM), substance P (SP) and vasoactive intestinal peptide (VIP), and the synthesizing enzyme for acetylcholine, choline acetyltransferase (ChAT) were localized immunohistochemically in nerve cell bodies of the submucous ganglia in the small intestine of the guinea-pig. VIP-like immunoreactivity was found in 45% of submucous neurons. ChAT immunoreactivity was observed in a separate group of nerve cells, which made up 54% of the total population. There were three subsets of neurons immunoreactive for ChAT: (1) ChAT neurons that also contained immunoreactivity for each of the peptides CCK, SOM and NPY, representing 29% of all submucous neurons; (2) ChAT neurons that also contained SP-like immunoreactivity, representing 11% of all submucous neurons, and (3) ChAT cells that did not contain any detectable amount of the peptides that were localized in this study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217152
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  • 9
    Electronic Resource
    Electronic Resource
    Neurochemically similar myenteric and submucous neurons directly traced to the mucosa of the small intestine (1985)
    Springer
    Cell & tissue research 241 (1985), S. 155-163 
    Details
    ISSN: 1432-0878
    Keywords: Calcitonin gene-related peptide ; Cholecystokinin ; Choline acetyltransferase ; Neuropeptide Y ; Somatostatin ; Enteric nervous system ; Intestine, small ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Antisera to neuropeptide Y (NPY) gave an intense immunohistochemical reaction of certain nerve cells in the myenteric and submucous plexuses of the guinea-pig small intestine. Each nerve cell had up to 20 branching, tapering processes that were less than ∼50 μm long and a long process that could be followed for a considerable distance. This morphology corresponds to that of the type-III cells of Dogiel. The long process of each myenteric cell ran through the circular muscle to the submucosa, and in most cases the process could be traced to the mucosa. The submucous nerve cell bodies also had processes that extended to the mucosa. These cell bodies, in both plexuses, also stained with antisera raised against calcitonin generelated peptide (CGRP), cholecystokinin (CCK), choline acetyltransferase (ChAT) and somatostatin (SOM), but did not stain with antibodies against enkephalin, substance P or vasoactive intestinal peptide. Thus, it has been possible for the first time to trace the processes of chemically specified neurons through the layers of the intestinal wall and to show by a direct method that CGRP/CCK/ChAT/NPY/ SOM myenteric and submucous nerves cells provide terminals in the mucosa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214637
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  • 10
    Electronic Resource
    Electronic Resource
    The source of the nerve fibres forming the deep muscular and circular muscle plexuses in the small intestine of the guinea-pig (1987)
    Springer
    Cell & tissue research 247 (1987), S. 497-504 
    Details
    ISSN: 1432-0878
    Keywords: Enteric nervous system ; Intestine, small ; Nerves, degeneration ; Neuronal connections ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A quantitative ultrastructural study was made of the neuntes forming the deep muscular and circular muscle plexuses of the guinea-pig small intestine following microsurgical lesions designed to interrupt intrinsic and extrinsic nerve pathways within the intestinal wall. Removal of a collar of longitudinal muscle with attached myenteric plexus from the circumference of a segment of small intestine resulted in the subsequent disappearance of 99.3% of neurites in the underlying circular muscle. The few surviving neurites in the deep muscular plexus and circular muscle disappeared completely from lesioned segments that were, in addition, extrinsically denervated surgically. These results indicate that the majority of nerve fibres in the deep muscular and circular muscle plexuses of the guinea-pig small intestine is intrinsic to the intestine and originates from nerve cell bodies located in the overlying myenteric plexus. At the light-microscopic level, nerve bundles were traced from the myenteric plexus to the circular muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215742
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