Effects of single and simultaneous combined nanoinjections of Met-enkephalin into rat midbrain and medulla on activity of differentially nociresponsive ventral medullary neurons

J. Peter Rosenfeld*, Kun Hou Huang, Lang Yan Xia

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Neuronal activity classified by receptive field, adequate stimulus, and raphe-spinal (R-S) projection in 48 lightly anaesthetized rats was recorded from raphe magnus (RM) area. Effects of nanoinjections of Met-enkephalin in periaqueductal gray (PAG; 2 or 10 μg), nucleus reticularis paragigantocellularis (PGC; 1 or 5 μg), and both sites (conjointly) were studied. Most of the 78 neurons studied responded to noxious stimulation, some with increased responses ('on-cells') and some with decreased responses ('off-cells'). Major findings: (1) Met-enkephalin in PAG and PGC depressed the response of on-cells and enhanced the response of off-cells; (2) for a given RM or R-S cell, PAG and PGC effects were typically identical; and (3) conjoint injections tended to produce greater effects than single effects, whether enhancing or depressing,.

Original languageEnglish (US)
Pages (from-to)199-209
Number of pages11
JournalBrain research
Volume508
Issue number2
DOIs
StatePublished - Feb 5 1990

Keywords

  • Nucleus reticular paragigantocellularis
  • Opiate analgesia
  • Pain
  • Periaqueductal gray
  • Raphe magnus

ASJC Scopus subject areas

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

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