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  • Electronic Resource  (6)
  • 1985-1989  (6)
  • Guinea-pig ileum  (3)
  • Neuropeptide Y  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 336 (1987), S. 419-424 
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 339 (1989), S. 166-172 
    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
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 338 (1988), S. 397-400 
    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
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 247 (1987), S. 377-384 
    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
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  • 5
    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
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  • 6
    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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