Research article summary (published 30 Dec 1980):

[Are bulbo-spinal serotonergic systems involved in the detection of nociceptive messages? (author's transl)]

(Les systèmes sérotoninergiques bulbo-spinaux jouent-ils un rôle dans la détection des messages nociceptifs?)

Full Abstract

Intensely noxious peripheral stimuli of the anaesthetized rat produce two changes in the activity of convergent dorsal horn units: the segmental neuronal pool is activated, while all other convergent neurones are inhibited. These Diffuse Noxious Inhibitory Controls (DNIC) are highly potent (60-80% inhibition) and suppress all convergent neuronal activity, whether spontaneous or evoked by noxious or nonnoxious stimuli. On the other hand, they have no effect on other dorsal horn cell types, including noxious-only and proprioceptive units. The "DNIC" circuits include at least one supraspinal relay since DNIC is not seen in spinal animals. Furthermore, they are greatly reduced by lesions of the Nucleus Raphé Magnus (NRM). It has been shown that this nucleus massively projects onto the spinal cord, in particular onto the dorsal horn, and that stimulation of the NRM results in convergent unit inhibition of the same degree of magnitude as with DNIC. The role of serotonergic mechanisms in DNIC can be demonstrated pharmacologically: pCPA pre-treatment (3 daily I.P. injections, 300 mg/kg) or cinanserin (4 mg/kg I.V.) both result in a potent decrease (50-80%). We have proposed that the nociceptive message from the convergent units could result in a contrast between activity of the activated segmental pool and silence of the remaining convergent units. If this hypothesis can be verified, then some raphé nuclei and brain stem serotonergic pathways may function as filters in the detection of nociceptive messages, allowing extraction of information from somatic background activity including the firing from peripheral mechanoreceptors. While superficially paradoxical in fact our hypothesis fits well with the observation of profound analgesia following NRM stimulation: indeed, this hypothetical contrast would be completely eliminated by NRM stimulation since both neuronal pools would then be inhibited.

Author information

Author/s: Le Bars, D (D); Dickenson, A H (AH); Rivot, J P (JP); Chitour, D (D); Chaouch, A (A); Kraus, E (E); Besson, J M (JM);

Journal and publication information

Publication Type: English Abstract; Journal Article; Research Support, Non-U.S. Gov't

Journal: Journal de physiologie (J Physiol (Paris)), published in FRANCE. (Language: fre)

Reference: 1981-; vol 77 (issue 2-3) : pp 463-71

Dates: Created 1981/12/22; Completed 1981/12/22; Revised 2006/11/15;

PMID: 6270318, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Animals Brain Stem - physiopathology Cinanserin - pharmacology Electric Stimulation Neurons - drug effects; physiology Nociceptors - drug effects; physiology Pain - physiopathology

Pain - physiopathology Raphe Nuclei - physiopathology Rats Receptors, Serotonin - physiology Serotonin - physiology Spinal Cord - physiopathology Synaptic Transmission

Associated Chemicals: Receptors, Serotonin (0) ; Cinanserin (1166-34-3) ; Serotonin (50-67-9)

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