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  • 1
    Electronic Resource
    Electronic Resource
    The peristaltic reflex: An analysis of the nerve pathways and their pharmacology (1976)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 294 (1976), S. 47-60 
    Details
    ISSN: 1432-1912
    Keywords: Autonomic pharmacology ; Peristalsis ; Intestine ; 5-hydroxytryptamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The enteric reflexes in isolated segments of the distal colon and rectum of the guinea-pig were studied by applying localized distensions and recording the consequent changes in circular muscle activity, and by recording tension changes in the circular muscle during the propulsion of a bolus in vitro. Lesions of the wall of the colon were made to locate nerve pathways involved in the reflexes and pharmacological tests were applied to investigate the natures of transmitters released and the types of receptors involved. Distension produced a transient contraction of the circular muscle on the oral side and sustained relaxation on the anal side. Both reflexes were nervemediated. They were elicited in segments deprived of mucosa and submucosa. Interruption of Auerbach's plexus, but not interruption of the submucosal plexus, prevented their conduction. The ascending excitatory reflex was partly blocked by hyoscine and was also partly blocked by methysergide or by making the preparation tachyphylactic to the excitatory action of 5-hydroxytryptamine. The ascending excitatory pathways apparently involve neurons releasing a 5-HT-like transmitter as well as cholinergic neurons. The descending inhibitory reflex was not antagonized by hyoscine, guanethidine, methysergide or mepyramine. It is assumed that the inhibitory neurons activated in this reflex are identical with the noncholinergic, non-adrenergic, enteric inhibitory neurons found throughout the intestine. If both the ascending excitatory and descending inhibitory reflexes acted simultaneously on the same area of circular muscle, the inhibitory response tended to dominate. Pellets of faeces, covered by a thin layer of resin, were introduced into the oral ends of isolated segments of colon. They were propelled analwards at speeds of 0.5–1.6 mm/s. Tension records showed that the pellets were preceded by relaxation and followed by a ring of contraction. The propulsion was blocked by both hyoscine and methysergide. Descending waves of contraction were also observed in empty segments of colon. These occurred spontaneously or were initiated by stretch. They did not occur in the presence of hyoscine or tetrodotoxin. It is postulated that three factors may contribute to propulsion in the guinea-pig distal colon: ascending excitatory reflexes which evoke contractions above a bolus; descending inhibitory reflexes which cause relaxations below; and contractions which, once set up in the circular muscle, travel in an anal direction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692784
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  • 2
    Electronic Resource
    Electronic Resource
    Evidence that axons containing substance P in the guinea-pig ileum are of intrinsic origin (1979)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 307 (1979), S. 57-63 
    Details
    ISSN: 1432-1912
    Keywords: Substance P ; Intestine ; Autonomic nervous system ; Peptidergic nerves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Acid extracts from both normal and extrinsically denervated ileum contained a compound which was indistinguishable from synthetic substance P; this compound was assayed by examining its contractile effect on the longitudinal muscle of segments of ileum in which receptors for acetylcholine and histamine were blocked. Contractions caused by the compound were markedly and selectively antagonized when the ileum was made insensitive to the action of substance P. The activities in the extract and of synthetic substance P were both destroyed by chymotrypsin but were not affected by trypsin or carboxypeptidase B. The concentrations of substance P-like material in normal and extrinsically denervated segments were not significantly different, being equivalent to 0.48 μg of substance P per g of external muscle plus myenteric plexus. A compound with substance P-like activity was liberated by stimulation of intramural nerves, either electrically or by dimethylphenylpiperazinium, in both normal and extrinsically denervated segments of ileum. The release of this compound was prevented by tetrodotoxin and its action on the muscle was blocked when the ileum was made insensitive to the action of substance P. Experiments with transmural stimulation showed that excitatory nerve pathways involving substance P neurons extend for less than 4 cm along the intestine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00506552
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructural studies of the myenteric plexus and smooth muscle in organotypic cultures of the guinea-pig small intestine (1995)
    Springer
    Cell & tissue research 280 (1995), S. 627-637 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Myenteric plexus ; Smooth muscle ; Organotypic culture ; Ultrastructure ; Intestine ; small ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. External muscle and myenteric plexus from the small intestine of adult guinea-pigs were maintained in vitro for 3 or 6 days. Myenteric neurons and smooth muscle cells from such organotypic cultures were examined at the electron-microscopic level. An intact basal lamina was found around the myenteric ganglia and internodal strands. Neuronal membranes, nuclei and subcellular organelles appeared to be well preserved in cultured tissues and ribosomes were abundant. Dogiel type-II neurons were distinguishable by their elongated electron-dense mitochondria, numerous lysosomes and high densities of ribosomes. Vesiculated nerve profiles contained combinations of differently shaped vesicles. Synaptic membrane specializations were found between vesiculated nerve profiles and nerve processes and cell bodies. The majority of nerve fibres were well preserved in the myenteric ganglia, in internodal strands and in bundles running between circular muscle cells. No detectable changes were found in the ultrastructure of the somata and processes of glial cells. Longitudinal and circular muscle cells from cultured tissue had clearly defined membranes with some close associations with neighbouring muscle cells. Caveolae occurred in rows that ran parallel to the long axis of the muscle cells. These results indicate that the ultrastructural features of enteric neurons and smooth muscle of the guinea-pig small intestine are well preserved in organotypic culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318365
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  • 4
    Electronic Resource
    Electronic Resource
    Projections of specific morphological types of neurons within the myenteric plexus of the small intestine of the guinea-pig (1996)
    Springer
    Cell & tissue research 285 (1996), S. 149-156 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Organotypic culture ; Myenteric plexus ; Retrograde transport ; Intestine ; small ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The projections of myenteric neurons within the myenteric plexus of the guinea-pig small intestine were established using retrograde tracing in organotypic culture. Three days after applying the fluorescent dye DiI to a single internodal strand in the myenteric plexus, 500–1000 nerve cell bodies were labelled. Of these, 77% were located oral to the application site, 15% were located anally and 7% were located within 1 mm of this site. Three major morphological types of neurons could be distinguished. Dogiel type I neurons had lamellar dendrites and single axons, Dogiel type II neurons had large smooth cell bodies and several long processes, and filamentous neurons had smooth ovoid cell bodies, single axons and several filamentous dendrites. Dogiel type I, II and filamentous neurons accounted for 54.6%, 38% and 7.4% of all filled cells, respectively. Labelled nerve cell bodies were present up to 13 mm aboral to the DiI application site; all neurons more than 2 mm aboral had Dogiel type I features. On the oral side, Dogiel type I neurons were found up to 110 mm, Dogiel type II neurons up to 100 mm and filamentous neurons up to 80 mm. Neurons with 2 mm oral or aboral to the DiI application site were located up to 7 mm circumferentially and were mainly Dogiel type II cells. This work revealed remarkable polarity within the myenteric plexus, with a significant prevalence of myenteric neurons projecting anally for longer distances than those projecting orally. These long pathways are probably involved in the coordination of intestinal motility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050630
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  • 5
    Electronic Resource
    Electronic Resource
    Distribution and projections of neurons with immunoreactivity for both gastrin-releasing peptide and bombesin in the guinea-pig small intestine (1984)
    Springer
    Cell & tissue research 235 (1984), S. 285-293 
    Details
    ISSN: 1432-0878
    Keywords: Enteric nervous system ; Intestine ; Neuropeptides ; Gastrin releasing peptide ; Bombesin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Bombesin-like and gastrin-releasing peptide (GRP)-like immunoreactivities were localized in nerves of the guinea-pig small intestine and celiac ganglion with the use of antibodies raised against the synthetic peptides. The anti-bombesin serum (preincubated to avoid cross reactivity with substance P) and the anti-GRP serum revealed the same population of neurons. Preincubation of the antibombesin serum with bombesin abolished the immunoreactivity in nerves while absorption of the anti-GRP serum with either bombesin or the 14–27 C-terminal of GRP only reduced the immunoreactivity. The immunoreactivity was abolished by incubation with GRP 1–27. Immunoreactive nerves were found in the myenteric plexus, circular muscle, submucous plexus and in the celiac ganglion. Faintly reactive nerve cell bodies were found in the myenteric ganglia (3.2% of all neurons) but not in submucous ganglia. After all ascending and descending pathways in the myenteric plexus had been cut, reactive terminals disappeared in the myenteric plexus, circular muscle (including the deep muscular plexus) and the submucous plexus on the anal side. After the mesenteric nerves were cut no changes were observed in the intestinal wall but the reactive fibres in celiac ganglia disappeared. It is deduced that GRP/bombesin-immunoreactive nerve cell bodies in myenteric ganglia project from the myenteric plexus to other myenteric ganglia situated further anally (average length 12 mm), anally to the circular muscle (average length 9 mm), anally to submucous ganglia (average length 13 mm) and external to the intestine to the celiac ganglia. It is concluded that the GRP/bombesin-reactive neurons in the intestinal wall represent a distinct population of enteric neurons likely to be involved in controlling motility and in the coordination of other intestinal functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217852
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  • 6
    Electronic Resource
    Electronic Resource
    Immunohistochemical evidence for the presence of calcium-binding proteins in enteric neurons (1988)
    Springer
    Cell & tissue research 252 (1988), S. 79-87 
    Details
    ISSN: 1432-0878
    Keywords: Calcium-binding protein ; Enteric nervous system ; Intestine ; Immunocytochemistry ; Guinea-pig ; Rat ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunoreactivity for vitamin D-dependent calcium-binding protein (CaBP) has been localized in nerve cell bodies and nerve fibres in the gastrointestinal tracts of guinea-pig, rat and man. CaBP immunoreactivity was found in a high proportion of nerve cell bodies of the myenteric plexus, particularly in the small intestine. It was also found in submucous neurons of the small and large intestines. Immunoreactive nerve fibres were numerous in the myenteric ganglia, and were also common in the submucous ganglia and in the intestinal mucosa. Immunoreactive fibres were rare in the circular and longitudinal muscle coats. In the myenteric ganglia of the guinea-pig small intestine the immunoreactivity is restricted to one class of nerve cell bodies, type-II neurons of Dogiel, which display calcium action potentials in their cell bodies. These neurons were also immunoreactive with antibodies to spot 35 protein, a calcium-binding protein from the cerebellum. From the distribution of their terminals and the electrophysiological properties of these neurons it is suggested they might be sensory neurons, or perhaps interneurons. The discovery of CaBP in restricted sub-groups of enteric neurons may provide an important key for the analysis of their functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213828
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  • 7
    Electronic Resource
    Electronic Resource
    Distribution, pathways and reactions to drug treatment of nerves with neuropeptide Y- and pancreatic polypeptide-like immunoreactivity in the guinea-pig digestive tract (1983)
    Springer
    Cell & tissue research 234 (1983), S. 71-92 
    Details
    ISSN: 1432-0878
    Keywords: Enteric nervous system ; Intestine ; Noradrenergic nerves ; Pancreatic polypeptide ; Neuropeptide Y ; Neuropeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pancreatic polypeptide-like immunoreactivity (PPLI) has been localized in nerves of the guinea-pig stomach and intestine with the use of antibodies raised against avian, bovine and human pancreatic polypeptide (PP), the C-terminal hexapeptide of mammalian PP, and against the related peptide, NPY. Each of the antibodies revealed the same population of neurones. Reactive cell bodies were found in both myenteric (5% of all neurones) and submucous ganglia (26% of all neurones) of the small intestine, and varicose processes were observed in the myenteric plexus, circular muscle, mucosa and around arterioles. The nerves were unaffected by bilateral subdiaphragmatic truncal vagotomy, but the staining of the periarterial nerves disappeared after treatment of animals with reserpine or 6-hydroxydopamine and was also absent after mesenteric nerves had been cut and allowed to degenerate. Vascular nerves showing immunoreactivity for dopamine it-hydroxylase and PPLI had the same distribution. It is concluded that PPLI is located in periarterial noradrenergic nerves. However, other noradrenergic nerves in the intestine do not show PPLI, and PPLI also occurs in nerves that are not noradrenergic. Analysis of changes in the distribution of terminals after microsurgical lesions of pathways in the small intestine showed that processes of myenteric PP-nerve cells provide terminals in the underlying circular muscle and in myenteric ganglia up to about 2 mm more anal. Submucous PP-cell bodies provide terminals to the mucosa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217403
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