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Separation of A- versus C-nociceptive inputs into spinal-brainstem circuits

Parry, D M, Macmillan, F M, Koutsikou, Stella, McMullan, S, Lumb, B M (2008) Separation of A- versus C-nociceptive inputs into spinal-brainstem circuits. Neuroscience & Biobehavioral Reviews, 152 (4). pp. 1076-1085. ISSN 0149-7634. (doi:10.1016/j.neuroscience.2008.01.018) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided) (KAR id:84448)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided. (Contact us about this Publication)
Official URL
https://doi.org/10.1016/j.neuroscience.2008.01.018

Abstract

This study was designed to determine the organization of nociceptive inputs with different behavioral significance into spinal-brainstem circuits in the rat. Induction of Fos protein was used to localize spinal dorsal horn and hypothalamic neurons activated by noxious heating of the hind paw dorsum at rates known to preferentially activate C- or A-heat nociceptors. This was combined with retrograde transport of cholera toxin subunit B from the dorsolateral/lateral- (DL/L-) or the ventrolateral- (VL-) periaqueductal gray (PAG) in order to map the organization of A- and C-fiber input to spinal-brainstem circuits. The majority of dorsal horn heat-activated neurons were located in laminae I and II. A significantly larger proportion of C-fiber-activated neurons projected to the VL-PAG (P<0.05) compared with its DL/L-sector. In contrast, there was no columnar separation in the projections of A-fiber-activated neurons. However, a significantly greater proportion of A-fiber-activated neurons (P<0.05) were retrogradely labeled from the DL/L-PAG, when compared with C-fiber-activated neurons. A large proportion (25-50%) of A- and C-fiber-activated neurons in the lateral spinal nucleus projected to the PAG. A-fiber-activated neurons were found throughout the rostral hypothalamus but those projecting to the PAG were focused in the lateral area of the anterior hypothalamus (LAAH), from where approximately 20% projected to the VL-PAG, which was significantly more than to the DL/L PAG (P<0.05). We hypothesize that the organization of A- versus C-fiber inputs to the PAG enables the coordination of coping strategies appropriate to meet the demands imposed by these different noxious stimuli. Hypothalamic-PAG projections activated by A-fiber inputs did not reflect this level of organization and we suggest that this may relate to their role in thermoregulation as opposed to autonomic responses to particular nociceptive inputs.

Item Type: Article
DOI/Identification number: 10.1016/j.neuroscience.2008.01.018
Subjects: Q Science > QP Physiology (Living systems)
Divisions: Divisions > Division of Natural Sciences > Medway School of Pharmacy
Depositing User: Stella Koutsikou
Date Deposited: 25 Nov 2020 13:20 UTC
Last Modified: 16 Feb 2021 14:16 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/84448 (The current URI for this page, for reference purposes)
Koutsikou, Stella: https://orcid.org/0000-0003-2933-3637
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