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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 55 (1990), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Serotonin binding protein (SBP) is a constituent of the synaptic vesicles of serotonergic neurons. Two types of SBP, with molecular masses of 45 kDa and 56 kDa, have been purified. To determine whether there are shared epitopes between the two forms of SBP, we raised and tested for cross-reactivity monoclonal antibodies (MAbs) against each form of SBP. We obtained 12 MAbs, all of which recognize both forms of SBP. Hybridoma clones were produced by fusing P3 ± 63Ag8.653 mouse myeloma cells with spleen cells from a mouse that had been immunized with 45-kDa or 56-kDa SBP. Culture supernatants were screened for the presence of anti-SBP antibodies. MAb isotypes were determined by immunodiffusion, using immunoglobulin type-specific antisera. Each antibody to SBP consisted of only a single subclass of immunoglobulin (IgM). We obtained 12 MAbs, each of which interacted with both forms of SBP, as judged by enzyme-linked immunosorbent assay and immunoblot analysis. Ascites fluid to one clone (44–10) was obtained and affinity-purified. In the presence of goat anti-mouse IgM, the partially purified 44–10 antibodies quantitatively immunoprecipitated SBP from crude brain extracts. Immunoblotting revealed two major bands corresponding to 45 kDa and 56 kDa and a minor band corresponding to 68 kDa. MAb 44–10 blocked the binding of [3H]serotonin ([3H]5-HT) to 45-kDa and 56-kDa SBP in a concentration-dependent manner. The 68-kDa protein was found to bind [3H]5-HT. Sites reacting with Mab 44–10 were located immunocytochemically in sections of rat brain. 5-HT immunoreactivity was localized simultaneously in the same sections by using affinity-purified rabbit anti-5-HT antibodies and species-specific secondary antibodies coupled to a contrasting fluorophore. MAb 44–10 immunostaining involved neuronal cell bodies, neurites, and terminals. This immunostaining was intense within the nuclei of the median raphe and the B9 cell group. Coincident expression with 5-HT was observed; however, MAb 44–10 also immunostained many neurons in which 5-HT immunoreactivity was not seen. These observations may indicate that SBP is distributed more widely in the brain than 5-HT; however, because SBP immunoreactivity is not found in nonserotonergic neurons when monospecific polyclonal antibodies are used for immunocytochemistry, it seems more likely that some nonserotonergic neurons contain another protein (such as the 68-kDa SBP) that also contains an epitope recognized by MAb 44–10. Nevertheless, these data demonstrate that MAb 44–10 reacts with the 5-HT binding domain of 45-kDa and 56-kDa SBP and will be a valuable tool for analyzing these proteins.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Groups of neurons intrinsic to the mammalian myenteric plexus have been shown to have both tryptophan hydroxylase and a specific uptake mechanism for serotonin. They are probably serotonergic. A soluble protein with a high binding affinity for serotonin, similar to a protein previously found in rat brain by TAMIR & HUANG (1974), has now been found in the myenteric plexus of both rabbit and guinea pig. Partial purification of the protein from the rabbit's myenteric plexus by ammonium sulfate fractionation increased the ratio of specific to nonspecific serotonin binding almost 3-fold. Two dissociation constants for serotonin binding were obtained by equilibrium dialysis: 6.7 × 10−10 M and 4.8 × 10−7 M. The protein was similar to the soluble serotonin-binding protein of CNS: the indole derivatives 5, 6- and 5, 7-dihydroxytryptamine, and 6-hydroxytryptamine inhibited serotonin binding by 50% at 10−7 M; norepinephrine was a poor inhibitor of serotonin binding; most of the serotonin-protein complex had a very high molecular weight and did not penetrate a 6.5% acrylamide gel. The appearance of the serotonin binding protein during development of the intestine in fetal rabbit correlates closely with the development of a serotonin uptake mechanism by nerves of this tissue and precedes the ingrowth of the adrenergic innervation. In-vitro administration of 6-hydroxydopamine to adult animals has no effect on the binding capacity for serotonin. Binding activity in denervated preparations is only 1/5 that of innervated tissue. It is concluded that the serotonin-binding protein, which has been found associated with serotonergic pathways in the CNS, is found associated with serotonergic neurons in the periphery as well. Since a similar serotonin-binding protein is also found in sheep thyroid, which stores but does not take up serotonin, the protein may be a component of the serotonin storage mechanism.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Alimentary pharmacology & therapeutics 20 (2004), S. 0 
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The gut is the only organ that can display reflexes and integrative neuronal activity even when isolated from the central nervous system. This activity can be triggered by luminal stimuli that are detected by nerves via epithelial intermediation. Epithelial enterochromaffin cells act as sensory transducers that activate the mucosal processes of both intrinsic and extrinsic primary afferent neurones through their release of 5-hydroxytryptamine (5-HT). Intrinsic primary afferent neurones are present in both the submucosal and myenteric plexuses. Peristaltic and secretory reflexes are initiated by submucosal intrinsic primary afferent neurones, which are stimulated by 5-HT acting at 5-HT1P receptors. 5-HT acting at 5-HT4 receptors enhances the release of transmitters from their terminals and from other terminals in prokinetic reflex pathways. Signalling to the central nervous system is predominantly 5-HT3 mediated, although serotonergic transmission within the enteric nervous system and the activation of myenteric intrinsic primary afferent neurones are also 5-HT3 mediated. The differential distribution of 5-HT receptor subtypes makes it possible to use 5-HT3 antagonists and 5-HT4 agonists to treat intestinal discomfort and motility. 5-HT3 antagonists alleviate the nausea and vomiting associated with cancer chemotherapy and the discomfort from the bowel in irritable bowel syndrome; however, because 5-HT-mediated fast neurotransmission within the enteric nervous system and the stimulation of mucosal processes of myenteric intrinsic primary afferent neurones are 5-HT3 mediated, 5-HT3 antagonists tend to be constipating and should be used only when pre-existing constipation is not a significant component of the problem to be treated. In contrast, 5-HT4 agonists, such as tegaserod, are safe and effective in the treatment of irritable bowel syndrome with constipation and chronic constipation. They do not stimulate nociceptive extrinsic nerves nor initiate peristaltic and secretory reflexes. Instead, they rely on natural stimuli to activate reflexes, which they strengthen by enhancing the release of transmitters in prokinetic pathways. Finally, when all the signalling by 5-HT is over, its action is terminated by uptake into enterocytes or neurones, which is mediated by the serotonin reuptake transporter. In inflammation, serotonergic signalling is specifically diminished in the mucosa. Transcripts encoding tryptophan hydroxylase-1 and serotonin reuptake transporter are both markedly decreased. Successive potentiation of 5-HT and/or desensitization of its receptor could account for the symptoms seen in diarrhoea-predominant and constipation-predominant irritable bowel syndrome, respectively. Symptoms associated with the down-regulation of the serotonin reuptake transporter in the human mucosa in irritable bowel syndrome are similar to the symptoms associated with the knockout of the serotonin reuptake transporter in mice. The observation that molecular defects occur in the human gut in irritable bowel syndrome strengthens the hand of those seeking to legitimize the disease. At least it is not ‘all in your head’. The bowel contributes.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Neuroscience 4 (1981), S. 227-272 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 41 (1985), S. 863-868 
    ISSN: 1420-9071
    Keywords: 5-hydroxytryptamine ; serotonin ; receptors ; enteric nervous system ; gut ; radioautography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An enteric neural receptor for serotonin (5-HT) has been characterized. This receptor was assayed, using3H-5-HT as a radiologand, by rapid filtration of isolated enteric membranes and by radioautography. In addition, intracellular recordings were made from ganglion cells of the myenteric plexus. High affinity, saturable, reversible, and specific binding of3H-5-HT was demonstrated both to membranes of the dissected longitudinal muscle with adherent myenteric plexus and the mucosa-submucosa. Radioautographs showed these3H-5-HT binding sites to be in myenteric ganglia and in a broad unresolved band at the mucosal-submucosal interface. Antagonists active at receptors for other neurotransmitters than 5-HT, at either of the two known types of CNS 5-HT receptor, and at 5-HT uptake sites on serotonergic neurons failed to inhibit binding of3H-5-HT. The structural requirements of analogues for binding to the enteric 5-HT receptor matched the known pharmacology of M or neural 5-HT receptors. A novel 5-HT antagonist was found. This compound, N-acetyl-5-hydroxytryptophyl-5-hydroxytryptophan amide (5-HTP-DP), antagonized the action of 5-HT on type II/AH cells of the myenteric plexus but did not affect the release or actions of acetylcholine (nicotinic or muscarinic) or substance P. 5-HTP-DP was also an equally potent displacer of3H-5-HT from its binding sites on enteric membranes. It is concluded that the sites responsible for specific binding of3H-5-HT are enteric M or neural 5-HT receptors. These receptors differ from those now known to be present in the CNS.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 218 (1987), S. 149-156 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A light and electron microscope study of the small intestine of the little brown bat, Myotis lucifugus, was carried out at several stages in the animal's annual life cycle. An unusual morphological observation was the presence of cells in the lamina propria of the small intestine which were packed with a conspicuous basophilic granular material that appeared crystalline. Moreover, such cells were present only during the hibernation period and were therefore called “hibernation crystalloid” (HC) cells. By light microscopy, the crystal-like material was not sudanophilic, did not stain for nucleic acids, and did not contain acid phosphatase; it did show reactivity when stained by the periodic acid-Schiff procedure. By electron microscopy, the crystal-like material was found to be present in smooth, membrane-enclosed vacuoles along with an amorphous, dense granular substance. The crystal-line material occasionally formed rigid-appearing rods that reached lengths of 10 μm. The crystal-containing cells were contacted by axonal varicosities. It is suggested that these innervated HC cells represent a unique cell type with a gastrointestinal function, yet to be determined, that may be related to hibernation.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Recent electrophysiological studies of neurons of the myenteric plexus of the corpus of the guinea pig stomach have revealed that slow synaptic events are extremely rare. In contrast, they are commonly encountered in similar investigations of myenteric ganglia of the guinea pig small intestine. The current immunocytochemical analysis of the myenteric plexus and innervation of the muscularis externa of the corpus of the guinea pig stomach was undertaken in order to determine whether putative neurotransmitters capable of mediating slow synaptic events are present in gastric ganglia. A major difference between the small intestine and the stomach was found in the innervation of the musculature. Whereas the longitudinal muscle layer of the small intestine contains very few nerve fibers and is innervated mainly at its interface with the myenteric plexus, the longitudinal muscle of the corpus of the stomach contained as many varicose substance P (SP)-, vasoactive intestinal polypeptide (VIP)-, and neuropeptide Y (NPY)-immunoreactive axons as the circular muscle layer. These putative neurotransmitters were also present in the ganglia of the myenteric plexus, where varicose SP-, VIP-, and NPY-immunoreactive fibers encircled nonimmunoreactive neurons. Varicose 5-hydroxytryptamine (5-HT)-immunoreactive terminal axons were essentially limited to the myenteric plexus and were found both in ganglia and in interganglionic connectives, where they were particularly numerous; 5-HT-immunoreactive neurons appeared to be more abundant in the stomach than in the small intestine. Tyrosine hydroxylase (TH)- and calcitonin-gene-related-peptide (CGRP)-immunoreactive axons were also more common in the myenteric plexus than in the musculature, but of these, only the TH-immunoreactive neurites tended, like those of the other putative transmitters, to encircle neurons in myenteric ganglia. Evidence was obtained that, as in the small intestine, at least some of the SP-, VIP-, NPY-, and 5-HT-immunoreactive fibers in the stomach are derived from intrinsic gastric myenteric neurons. In contrast, unlike the small intestine, gastric myenteric ganglia appeared to lack intrinsic CGRP-immunoreactive neurons; therefore, the CGRP-immunoreactive gastric axons are probably of extrinsic origin. Since these fibers appeared to pass through ganglia without contacting many neurons and, like dorsal root ganglion neurons, coexpressed SP immunoreactivity, the CGRP-immunoreactive axons were probably mainly the gastric banches of visceral sensory neurons. On the other hand, the bulk of the SP-immunoreactive fibers did not coexpress CGRP immunoreactivity and so were probably intrinsic. These observations show that, although there are differences in the innervations of the myentric plexus and musculature of the corpus of the guinea pig stomach from those of the small intestine, the relative paucity of slow synaptic events encountered in gastric neurons cannot be simply attributed to an absence of putative transmitters capable of mediating these responses.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 191 (1978), S. 327-343 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Reserpine has been demonstrated in previous studies to induce the accumulation of lipid droplets in ventricular cardiac muscle cells of bats and this effect has been attributed to mediation by the sympathetic nervous system. The present study was done to evaluate the species specificity of this action of the drug. Reserpine caused lipid droplet accumulation in cardiocytes of guinea pigs and mice. However, in contrast to the action of the drug in bats, this action of reserpine in guinea pigs and mice could not be antagonized by chemical sympathectomy with 6-hydroxydopamine or by treatment of animals with phenoxybenzamine, atropine or hexamethonium. Like reserpine, fasting for as little as 24 hours induced lipid droplet accumulation in cardiocytes of guinea pigs and mice. This effect also could not be prevented by treatment with 6-hydroxydopamine indicating that the sympathetic nervous system was not involved in its mediation. Force-feeding guinea pigs given reserpine prevented the accumulation of lipid droplets normally induced by this drug. It is concluded that the lipid droplets accumulation in the hearts of guinea pigs that follows administration of reserpine is not due to a direct cardiotoxicity of the drug but is secondary to the failure of drug-treated animals to eat. Since the autonomic nervous system appears to mediate reserpine's cardiotoxicity in bats, the species difference revealed by these experiments probably results from an underlying physiological difference in the nervous systems of these animals.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 194 (1992), S. 142-154 
    ISSN: 0002-9106
    Keywords: Neural crest ; Development ; Pancreatic innervation ; Gut ; Enteric nervous system ; Phenotypic expression ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Neurons in ganglia of the myenteric plexus of the duodenum and stomach have recently been demonstrated to innervate pancreatic ganglia and transsynaptically to excite acinar and islet cells. The hypothesis that crestderived cells first colonize the foregut and secondarily enter the pancreas by way of the pancreatic buds was tested. Studies were done with fetal rats (days E11-E15). Pancreatic rudiments and foregut were explanted separately and in co-culture. The development of neurons in the explants, identified by demonstrating the immunoreactivities of neurofilaments and growthassociated protein-43 (GAP-43), provided an indirect assay for the presence of neural precursors in the tissue at the time of explantation. Cells of putative neural crest origin were visualized immunocytochemically using the monoclonal antibody, NC-1. Additional markers included the immunoreactivities of dopamine-β-hydroxylase (DBH), which is expressed by vagal crest-derived cells that colonize the bowel, neuropeptides (substance P and neuropeptide Y [NPY]) found in mature pancreatic neurons, and serotonin (5-HT), which is located in the cell bodies of enteric but not pancreatic neurons. Neurons were detected in cultures of foregut, but not pancreas, when these tissues were explanted by themselves at days E11 and E12. At E11 neural precursors did not leave explants of bowel or migrate into co-cultured pancreatic rudiments. When the foregut was explanted at E12, however, neural precursors migrated away from the bowel, giving rise both to distant ganglia and to neurons within co-cultured pancreatic rudiments. Intrapancreatic ganglia developed in the co-cultures even when the pancreatic attachment to the bowel was severed. Neurons appeared in pancreatic rudiments explanted by themselves on day E13. Neurons developing in pancreatic explants expressed the immunoreactivities of DBH, substance P, and NPY, but not 5-HT. These observations support the idea that pancreatic ganglia develop from crest-derived cells that first colonize the fetal rat foregut and there acquire the ability to colonize the pancreas. A later migration into the pancreatic rudiments of a subset of the original émigrés or their progeny between days E12 and E13 gives rise to a network of pancreatic ganglia that can be regarded as an extension of the enteric nervous system. © 1992 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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