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  • Enteric nervous system  (27)
  • Intestine  (7)
  • Guinea pig  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Evidence for two types of 5-hydroxytryptamine receptor on secretomotor neurons of the guinea-pig ileum (1989)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 339 (1989), S. 409-414 
    Details
    ISSN: 1432-1912
    Keywords: Enteric nervous system ; 5-Hydroxytryptamine ; Electrolyte transport ; Small intestine ; Secretomotor neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Flat sheet preparations of the mucosa plus submucosa from the guinea-pig ileum were placed in Ussing chambers so that short circuit currrent (I sc), an index of electrolyte movement across the mucosa, could be measured. In these preparations, 5-hydroxytryptamine (5-HT) increasesI sc indirectly by stimulating both cholinergic and non-cholinergic secretomotor neurons. The 5-HT3 receptor antagonist, ICS 205–930 (10−13–10−5 M), substantially depressed the secretory response due to 5-HT (10−6 M), but not that produced by direct activation of muscarinic receptors on the mucosal epithelium with carbachol (10−6 M), or by stimulation of secretomotor neurons with substance P (10−8 M) or 1,1-dimethyl-4-phenylpiperazinium (10−5 M). The residual response to 5-HT, after the addition of a maximally effective concentration of ICS 205–930 (10−6 M), was further reduced by hyoscine (10−7M). When that part of the 5-HT response attributable to the release of acetylcholine was blocked by hyoscine (10−7M), ICS 205–930 did not further modify the response to 5-HT. The hyoscine-resistant component was, however, sustantially depressed by tetrodotoxin (3.5 × 10−7 M). The response remaining after ICS 205–930 and hyoscine was not affected by methysergide (2 × 10− 5 M) or cyproheptadine (10−7 M). We conclude that there are ICS 205–930 sensitive 5-HT receptors on cholinergic secretomotor neurons, and ICS 205–930, methysergide, and cyproheptadine insensitive 5-HT receptors on non-cholinergic secretomotor neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00736055
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  • 2
    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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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Electrophysiological analysis of the actions of pituitary adenylyl cyclase activating peptide in the taenia of the guinea-pig caecum (1995)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 352 (1995), S. 538-544 
    Details
    ISSN: 1432-1912
    Keywords: Key words Pituitary adenylyl cyclase activating peptide (PACAP) ; Taenia caeci ; Electrophysiology ; Enteric nervous system ; Inhibitory neurotransmitter ; Smooth muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The actions of pituitary adenylyl cyclase activating peptide (PACAP) on membrane potential and conductance were investigated in the taenia of the guinea-pig caecum. The possible role of PACAP in inhibitory transmission was also investigated. Membrane potentials of smooth muscle cells were measured by intracellular microelectrodes, in the presence of hyoscine and nifidepine (both 10-6M). To determine conductance changes, current was passed from external plate electrodes using the technique of Abe and Tomita (1968). PACAP-27 caused a concentration dependent hyperpolarization of the muscle with a maximum of 12–15 mV at 10-6M. The hyperpolarization caused by PACAP was associated with a substantial increase in membrane conductance. The hyperpolarization was abolished by apamin (10-6M), a blocker of small conductance, calcium-dependent, potassium channels, and was reduced to about 50% by suramin (10-4M), which is an antagonist of P2 receptors for purines. The hyperpolarization was not reduced by tetrodotoxin (2×10-6M), suggesting PACAP acts directly on the muscle. With continued exposure to PACAP, the hyperpolarization decayed back to resting membrane potential after several minutes, possibly due to receptor desensitization. Inhibitory junction potentials (IJPs) were markedly reduced in amplitude in the period of presumed receptor desensitization to PACAP, were abolished by tetrodotoxin, but were not affected by suramin. Apamin abolished the IJP and revealed a small excitatory junction potential. This study implies that PACAP released from nerve fibres in the taeniacaeci hyperpolarizes the muscle via an opening of apamin-sensitive potassium channels. The action is probably through type I PACAP receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169388
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  • 5
    Electronic Resource
    Electronic Resource
    Charybdotoxin and iberiotoxin but not apamin abolish the slow after-hyperpolarization in myenteric plexus neurons (1994)
    Springer
    Pflügers Archiv 428 (1994), S. 300-306 
    Details
    ISSN: 1432-2013
    Keywords: Potassium channels ; Enteric nervous system ; After-hyperpolarization ; Toxins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Myenteric neurons of guinea-pig ileum were studied with intracellular microelectrodes. The specific toxins charybdotoxin, iberiotoxin and apamin were used to characterize the prolonged after-hyperpolarizations of AH neurons in this preparation. Charybdotoxin and iberiotoxin blocked prolonged after-hyperpolarizations in 23 of 24 AH neurons, but apamin had no effect on 5 of 5 AH neurons. Abolition of the after-hyperpolarizations was accompanied by depolarization and increases in input resistances of those AH neurons affected, but the shapes of action potentials were unchanged. The excitability of the AH neurons was enhanced as shown by an increase in the number of action potentials evoked by a 500-ms depolarizing current pulse or by a train of 15 ms depolarizing current pulses (10Hz). The other class of myenteric neurons, S neurons, was also investigated. The 19 S neurons studied fired action potentials only at the start of a 500 ms depolarization, but the toxins had no effect on this behaviour or on their other properties. Intracellular injection of Neurobiotin into the neurons studied and subsequent immunohistochemical staining to localise the calcium-binding protein, calretinin, indicated that all major classes of S neurons were included in the sample. Thus, the prolonged after-hyperpolarizations in AH neurons may be due to opening of a large-conductance (BK) calcium-dependent potassium channel, but similar channels play little or no role in regulation of the excitability of S neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00724511
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  • 6
    Electronic Resource
    Electronic Resource
    The projections of chemically identified nerve fibres in canine ileum (1987)
    Springer
    Cell & tissue research 247 (1987), S. 377-384 
    Details
    ISSN: 1432-0878
    Keywords: Enkephalin ; Gastrin releasing peptide ; Neuropeptide Y ; Somatostatin ; Substance P ; Vasoactive intestinal peptide ; Enteric nervous system ; Intestine, small ; Dog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The projections of nerve fibres with immunoreactivity for the peptides enkephalin (ENK), gastrin-releasing peptide (GRP), neuropeptide Y (NPY), somatostatin (SOM), substance P (SP) and vasoactive intestinal peptide (VIP) were studied in canine small intestine by analysing the consequences of lesions of intrinsic and extrinsic nerves. Of peptides present in fibres supplying myenteric ganglia, GRP, SOM and VIP were in anally directed nerve pathways, whereas ENK and NPY were in orally directed pathways. Pathways ran for up to about 30 mm. SP fibres ran for short distances in both directions in the myenteric plexus. The circular muscle was supplied with ENK, NPY, SP and VIP fibres arising from the myenteric ganglia, whereas most mucosal SP and VIP fibres were deduced to arise from submucous ganglia. There were projections of fibres reactive for ENK, GRP, SOM, SP and VIP from myenteric ganglia to submucous ganglia. Antibodies to tyrosine hydroxylase were used to locate noradrenaline nerve fibres supplying the intestine; these fibres all disappeared when extrinsic nerves running through the mesentery to the small intestine were cut. It is deduced that there is an ordered pattern of projections of peptide-containing fibres in the canine intestine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218319
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  • 7
    Electronic Resource
    Electronic Resource
    Pathway-specific patterns of the co-existence of substance P, calcitonin gene-related peptide, cholecystokinin and dynorphin in neurons of the dorsal root ganglia of the guinea-pig (1987)
    Springer
    Cell & tissue research 248 (1987), S. 417-437 
    Details
    ISSN: 1432-0878
    Keywords: Substance P ; Calcitonin gene-related peptide ; Dynorphin ; Cholecystokinin ; Neuropeptide coexistence ; Sensory neurons ; Immunohistochemistry ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The co-existence of immunoreactivities to substance P (SP), calcitonin gene-related peptide (CGRP), cholecystokinin (CCK) and dynorphin (DYN) in neurons of the dorsal root ganglion (DRG) of guinea-pigs has been investigated with a double-labelling immunofluorescence procedure. Four main populations of neurons could be identified that contained different combinations of these peptides and had distinctive peripheral projections: (1) Neurons that contained immunoreactivity to SP, CGRP, CCK and DYN were distributed mainly to the skin. (2) Neurons with immunoreactivity to SP, CGPR and CCK, but not DYN, were distributed mainly to the small blood vessels of skeletal muscles. (3) Neurons with immunoreactivity to SP, CGRP and DYN, but not CCK, were distributed mainly to pelvic viscera and airways. (4) Neurons containing immunoreactivity to SP and CGRP, but not CCK and DYN, were distributed mainly to the heart, systemic blood vessels, blood vessels of the abdominal viscera, airways and sympathetic ganglia. Other small populations of DRG neurons containing SP, CGRP or CCK alone also were detected. Perikarya containing these combinations of neuropeptides were not found in autonomic ganglia. The peripheral axons of neurons containing immunoreactivity to at least SP and CGRP were damaged by chronic treatment with capsaicin. However, some sensory neurons containing CCK alone were not affected morphologically by capsaicin. These results clearly show that individual DRG neurons can contain many different neuropeptides. Furthermore, the combination of neuropeptides found in any particular neuron is related to its peripheral projection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218210
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  • 8
    Electronic Resource
    Electronic Resource
    Changes in surviving nerve fibers associated with submucosal arteries following extrinsic denervation of the small intestine (1988)
    Springer
    Cell & tissue research 253 (1988), S. 647-656 
    Details
    ISSN: 1432-0878
    Keywords: Neuropeptides ; Vascular innervation ; Immunohistochemistry ; Small intestine ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neuropeptide content of nerve fibers associated with submucosal arteries in the small intestine of guinea pigs was studied in whole-mount preparations using immunohistochemical methods. Tissues were obtained from normal animals or animals in which the small intestine had been extrinsically denervated. In normal animals, submucosal arteries are innervated by extrinsic sensory nerve fibers which contain both substance P and calcitonin gene-related peptide, and by sympathetic noradrenergic nerve fibers. In preparations obtained from animals 5–9 days after denervation, nerve fibers which contained substance P without detectable calcitonin gene-related peptide were associated with a few submucosal arteries. Nerve fibers which contained vasoactive intestinal peptide were also associated with some arteries. By 42–48 days after extrinsic denervation, substance P-containing fibers (without calcitonin gene-related peptide) and vasoactive intestinal peptide-containing fibers were associated with nearly every blood vessel. The extrinsic sympathetic nerve fibers did not regenerate during the course of this study. The nerve fibers associated with submucosal arteries in denervated tissues were not sensitive to capsaicin treatment. The alteration in the innervation of submucosal arterioles that follows extrinsic denervation of the gut may reflect either an increase in the neuropeptide content of the fibers, synthesis of a new peptide, or an increase in the number of fibers as a result of axonal sprouting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219756
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  • 9
    Electronic Resource
    Electronic Resource
    Galanin-immunoreactive neurons in the guinea-pig small intestine: their projections and relationships to other enteric neurons (1987)
    Springer
    Cell & tissue research 250 (1987), S. 607-615 
    Details
    ISSN: 1432-0878
    Keywords: Galanin ; Enteric nervous system ; Intestine, small ; Neuropeptides ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Galanin immunoreactivity was observed in nerve cell bodies and nerve fibres, but not in enteroendocrine cells, in the small intestine of the guinea-pig. Nerve terminals were found in the myenteric plexus, in the circular muscle, in submucous ganglia, around submucous arterioles, and in the mucosa. Lesion studies showed that all terminals were intrinsic to the intestine; those in myenteric ganglia arose from cell bodies in more orally placed ganglia. Myenteric nerve cells were also the source of terminals in the circular muscle. Galanin (GAL) was located in a population of submucous nerve cell bodies that also showed immunoreactivity for vasoactive intestinal peptide (VIP) and in a separate population that was immunoreactive for neuropeptide Y (NPY). Processes of the GAL/VIP neurons supplied submucous arterioles and the mucosal epithelium. Processes of GAL/NPY neurons ran to the mucosa. It is concluded that galanin immunoreactivity occurs in several functionally distinct classes of enteric neurons, amongst which are neurons controlling (i) motility, (ii) intestinal blood flow, and (iii) mucosal water and electrolyte transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218954
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  • 10
    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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