Activity of neurons in the rostral medulla of the halothane-anesthetized rat during withdrawal from noxious heat

Michael M. Morgan, Mary M. Heinricher

Research output: Contribution to journalArticle

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Abstract

The physiological and pharmacological properties of two classes of putative nociceptive modulatory neurons have been extensively characterized in the rostral ventromedial medulla (RVM) of the barbiturate-anesthetized rat. 'On-cells' show a burst of activity, and 'off-cells' a sudden pause immediately preceding the occurence of nocifensor reflexes. In the present study, we have characterized the reflex-related activity of RVM neurons in halothane-anesthetized rats to determine whether the properties of these neurons are dependent on barbiturate anesthesia. Both on- and off-cells were identified in this preparation. Repeated noxious stimulation was associated with a high level of ongoing activity in on-cells, and a low level in off-cells. These data thus demonstrate that the previously described reflex-related changes in RVM neuron activity are not specific to barbiturate-anesthetized preparations, and that a failure to demonstrate off-cells in some studies may result from these neurons being inactive following repeated testing with noxious stimuli.

Original languageEnglish (US)
Pages (from-to)154-158
Number of pages5
JournalBrain research
Volume582
Issue number1
DOIs
StatePublished - Jun 5 1992

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Keywords

  • Barbiturate
  • Nociception
  • Nucleus raphe magnus
  • Pain modulation
  • Tail flick
  • γ-Aminobutyric acid

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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