Participation of central descending nociceptive facilitatory systems in secondary hyperalgesia produced by mustard oil

M. O. Urban*, M. C. Jiang, G. F. Gebhart

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

117 Scopus citations

Abstract

The present series of experiments were designed to examine a potential role for central descending pain facilitatory systems in mediating secondary hyperalgesia produced by topical application of mustard oil and measuring the nociceptive tail-flick reflex in awake rats. Topical application of mustard oil (100%) to the lateral surface of the hind leg produced a facilitation of the tail-flick reflex that was significantly reduced in spinal transected animals. Mustard oil hyperalgesia was also inhibited in animals that had received electrolytic lesions in the rostral ventromedial medulla (RVM). Intrathecal (i.t.) administration of the non-selective cholecystokinin (CCK) receptor antagonist proglumide (10 μg) prior to mustard oil application completely blocked both the lesser and greater hyperalgesic responses observed in spinal transected and normal animals, respectively, and produced an inhibition of the tail-flick reflex in normal animals. Administration of the selective CCK, receptor antagonist L-365260 i.t. dose-dependently inhibited mustard oil hyperalgesia (ID50 = 364 ng) at doses approximately 5-fold less than the CCK(A) receptor antagonist devazepide (ID50 = 1760 ng). Similar to spinal proglumide, microinjection of the neurotensin antagonist SR48692 (3.5 μg) into the RVM blocked mustard oil hyperalgesia and inhibited the tail-flick reflex. These data suggest that secondary hyperalgesia produced by mustard oil is mediated largely by a central, centrifugal descending pain facilitatory system which involves neurotensin in the RVM and spinal CCK (via CCK(B) receptors). The inhibition of the tail-flick reflex produced by mustard oil following spinal or supraspinal administration of receptor antagonists suggests concurrent activation of central descending facilitatory and inhibitory systems.

Original languageEnglish (US)
Pages (from-to)83-91
Number of pages9
JournalBrain research
Volume737
Issue number1-2
DOIs
StatePublished - Oct 21 1996

Keywords

  • Cholecystokinin
  • Descending pain facilitation
  • Hyperalgesia
  • Mustard oil
  • Neurotensin
  • Rostral ventromedial medulla

ASJC Scopus subject areas

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

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