| Convergence of cutaneous, muscular and visceral noxious inputs onto ventromedial thalamic neurons in the rat. | |
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MedLine Citation:
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PMID: 12749962 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We have recently described a population of neurons in the lateral part of the ventromedial thalamus (VMl), that respond exclusively to noxious cutaneous stimuli, regardless of which part of the body is stimulated. The purpose of the present study was to investigate the convergence of cutaneous, muscular and visceral noxious inputs onto single, VMl neurons in anesthetized rats. VMl neurons were characterized by their responses to Adelta- and C-fiber activation as well as noxious heat applied to the hindpaw. We investigated whether they responded also to colorectal distensions. In an additional series of experiments, we tested the effects of colorectal, intraperitoneal, intramuscular and subcutaneous applications of the chemical irritant mustard oil (MO). The present study shows that a population of neurons located within the thalamic VMl nucleus, carries nociceptive somatosensory signals from the entire body. All these neurons responded to noxious cutaneous and intramuscular stimuli but not to levels of distension that could be considered innocuous or noxious, of the intact and inflammed colon and rectum. Although colorectal distension did not elicit VMl responses, convergence of visceral as well as muscle and cutaneous nociceptors was demonstrated by the increases in ongoing (background) discharges following intracolonic MO. A distinct effect is seen after MO injection into the lumen of the colon: an increase in ongoing activity for 15min but still a lack of effect of colorectal distension. Moreover, following inflammation induced by subcutaneous injections of MO VMl neurons developed responses to both thermal and mechanical innocuous skin stimulation, reminiscent of allodynia phenomena. It is suggested that the VMl contributes to attentional aspects of nociceptive processing and/or to the integration of widespread noxious events in terms of the appropriate potential motor responses. |
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Authors:
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Lénaïc Monconduit; Laurence Bourgeais; Jean-François Bernard; Luis Villanueva |
Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Pain Volume: 103 ISSN: 0304-3959 ISO Abbreviation: Pain Publication Date: 2003 May |
Date Detail:
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Created Date: 2003-05-16 Completed Date: 2003-07-21 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 7508686 Medline TA: Pain Country: Netherlands |
Other Details:
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Languages: eng Pagination: 83-91 Citation Subset: IM |
Affiliation:
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Inserm E 216, Neurobiologie de la douleur trigéminale, Faculté de Chirurgie dentaire, 11 boulevard Charles de Gaulle, 63000 Clermont-Ferrand, France. lenaic.monconduit@u-clermont1.fr |
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| MeSH Terms | |
Descriptor/Qualifier:
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Action Potentials
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drug effects,
physiology Afferent Pathways / physiology* Animals Drug Administration Routes / veterinary Electric Stimulation Male Morphine / pharmacology Muscles / innervation, physiology* Mustard Plant Naloxone / pharmacology Narcotic Antagonists / pharmacology Narcotics / pharmacology Neurons / physiology* Pain / physiopathology Physical Stimulation Plant Extracts / pharmacology Plant Oils Rats Rats, Sprague-Dawley Skin* / innervation Stimulation, Chemical Ventral Thalamic Nuclei / anatomy & histology, drug effects, physiology* Viscera / innervation, physiology* |
| Chemical | |
Reg. No./Substance:
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0/Narcotic Antagonists; 0/Narcotics; 0/Plant Extracts; 0/Plant Oils; 465-65-6/Naloxone; 57-27-2/Morphine; 8007-40-7/mustard oil |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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