Descending effect on spinal nociception by amygdaloid glutamate varies with the submodality of noxious test stimulation

Nora Bourbia, Boriss Sagalajev, Antti Pertovaara*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Amygdala has an important role in the processing of primary emotions, such as fear. Additionally, amygdala is involved in processing and modulation of pain. While the amygdala, particularly its central nucleus (CeA), has been shown to contribute to pain control, the descending pain regulation by the CeA is still only partly characterized. Here heat and mechanical nociception was tested in both hind limbs of healthy rats with a chronic guide cannula for microinjection of glutamate into the CeA of the left or right hemisphere. The aim was to assess whether the descending pain regulatory effect by glutamate in the amygdala varies with the submodality or the body side of nociceptive testing, brain hemisphere or the amygdaloid glutamate receptor. Motor performance was assessed with the Rotarod test. Amygdaloid glutamate, independent of the treated hemisphere, produced a dose-related heat and mechanical antinociception that varied with the submodality of testing. Heat antinociception was short lasting (minutes), bilateral and not reversed by blocking the amygdaloid NMDA receptor with MK-801. In contrast, mechanical antinociception lasted longer (>20. min), was predominantly contralateral and reversed by blocking the amygdaloid NMDA receptor. At an antinociceptive dose, amygdaloid glutamate failed to influence motor performance. The results indicate that independent of the brain hemisphere, the spatial extent and duration of the descending antinociceptive effect induced by amygdaloid glutamate varies with the amygdaloid glutamate receptor and the submodality of pain.

Original languageEnglish
Pages (from-to)26-31
Number of pages6
JournalNeuroscience Letters
Volume570
DOIs
Publication statusPublished - 6 Jun 2014
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported in part by the Yrjö and Tuulikki Ilvonen Foundation, the Emil Aaltonen Foundation, the Finnish Cultural Foundation, the Center for International Mobility (CIMO), the Sigrid Jusélius Foundation and the Academy of Finland.

Keywords

  • Amygdala
  • Descending pain control
  • Hemispheric lateralization
  • NMDA receptor
  • Submodality of pain

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