Do noradrenergic descending tract fibres contribute to the depression of transmission from group II muscle afferents following brainstem stimulation in the cat?

Bengt Skoog, Brian R Noga

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Two α2 noradrenaline antagonists, idazoxan and yohimbine, were injected in midlumbar segments of the spinal cord to test whether they counteract depression of field potentials evoked by group II muscle afferents by conditioning stimuli applied in the brainstem. The tested field potentials were those evoked monosynaptically in the intermediate zone of midlumbar segments. Their depression reflected thus the depression of transmission between group II fibres and their first relay neurones. The conditioning stimuli were applied either within the ipsilateral locus coeruleus/subcoeruleus or outside these nuclei (in the raphe magnus, raphe obscurus, or cuneiform nuclei). The brainstem evoked depression of the tested field potentials (n = 12) was reduced following injection of idazoxan or yohimbine to about two thirds of that which was evoked originally but in three cases to about one half. The study leads thus to the conclusion that noradrenergic descending tract neurones contribute to the depression of transmission from group II afferents to spinal interneurones and that such noradrenergic neurones are activated by stimuli applied within as well as outside their nuclei. However, the relative contribution of monoaminergic and non-monoaminergic descending tract neurones to the control of transmission from group II afferents to these neurones remains to be established.

Original languageEnglish
Pages (from-to)5-8
Number of pages4
JournalNeuroscience Letters
Volume134
Issue number1
DOIs
StatePublished - Dec 16 1991
Externally publishedYes

Fingerprint

Idazoxan
Brain Stem
Cats
Yohimbine
Neurons
Muscles
Afferent Neurons
Adrenergic Neurons
Raphe Nuclei
Locus Coeruleus
Interneurons
Evoked Potentials
Spinal Cord
Norepinephrine
Control Groups
Injections
Midbrain Reticular Formation
Nucleus Raphe Magnus

Keywords

  • Group II muscle afferent
  • Interneuron
  • Locus coeruleus
  • Monoamine
  • NA antagonist
  • Spinal cord

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

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title = "Do noradrenergic descending tract fibres contribute to the depression of transmission from group II muscle afferents following brainstem stimulation in the cat?",
abstract = "Two α2 noradrenaline antagonists, idazoxan and yohimbine, were injected in midlumbar segments of the spinal cord to test whether they counteract depression of field potentials evoked by group II muscle afferents by conditioning stimuli applied in the brainstem. The tested field potentials were those evoked monosynaptically in the intermediate zone of midlumbar segments. Their depression reflected thus the depression of transmission between group II fibres and their first relay neurones. The conditioning stimuli were applied either within the ipsilateral locus coeruleus/subcoeruleus or outside these nuclei (in the raphe magnus, raphe obscurus, or cuneiform nuclei). The brainstem evoked depression of the tested field potentials (n = 12) was reduced following injection of idazoxan or yohimbine to about two thirds of that which was evoked originally but in three cases to about one half. The study leads thus to the conclusion that noradrenergic descending tract neurones contribute to the depression of transmission from group II afferents to spinal interneurones and that such noradrenergic neurones are activated by stimuli applied within as well as outside their nuclei. However, the relative contribution of monoaminergic and non-monoaminergic descending tract neurones to the control of transmission from group II afferents to these neurones remains to be established.",
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AU - Skoog, Bengt

AU - Noga, Brian R

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N2 - Two α2 noradrenaline antagonists, idazoxan and yohimbine, were injected in midlumbar segments of the spinal cord to test whether they counteract depression of field potentials evoked by group II muscle afferents by conditioning stimuli applied in the brainstem. The tested field potentials were those evoked monosynaptically in the intermediate zone of midlumbar segments. Their depression reflected thus the depression of transmission between group II fibres and their first relay neurones. The conditioning stimuli were applied either within the ipsilateral locus coeruleus/subcoeruleus or outside these nuclei (in the raphe magnus, raphe obscurus, or cuneiform nuclei). The brainstem evoked depression of the tested field potentials (n = 12) was reduced following injection of idazoxan or yohimbine to about two thirds of that which was evoked originally but in three cases to about one half. The study leads thus to the conclusion that noradrenergic descending tract neurones contribute to the depression of transmission from group II afferents to spinal interneurones and that such noradrenergic neurones are activated by stimuli applied within as well as outside their nuclei. However, the relative contribution of monoaminergic and non-monoaminergic descending tract neurones to the control of transmission from group II afferents to these neurones remains to be established.

AB - Two α2 noradrenaline antagonists, idazoxan and yohimbine, were injected in midlumbar segments of the spinal cord to test whether they counteract depression of field potentials evoked by group II muscle afferents by conditioning stimuli applied in the brainstem. The tested field potentials were those evoked monosynaptically in the intermediate zone of midlumbar segments. Their depression reflected thus the depression of transmission between group II fibres and their first relay neurones. The conditioning stimuli were applied either within the ipsilateral locus coeruleus/subcoeruleus or outside these nuclei (in the raphe magnus, raphe obscurus, or cuneiform nuclei). The brainstem evoked depression of the tested field potentials (n = 12) was reduced following injection of idazoxan or yohimbine to about two thirds of that which was evoked originally but in three cases to about one half. The study leads thus to the conclusion that noradrenergic descending tract neurones contribute to the depression of transmission from group II afferents to spinal interneurones and that such noradrenergic neurones are activated by stimuli applied within as well as outside their nuclei. However, the relative contribution of monoaminergic and non-monoaminergic descending tract neurones to the control of transmission from group II afferents to these neurones remains to be established.

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