Comparison of somatostatin and morphine action on the responses of wide dynamic range cells in the dorsal horn to peripheral noxious mechanical and heat stimulation in cats

Jun Jung Sung Jun Jung, In Choi Young In Choi, Jimok Kim

Research output: Contribution to journalArticle

Abstract

The purpose of present study was to compare the effects of somatostatin (SOM) and morphine (Mor) on the responses of wide dynamic range (WDR) cells to peripheral noxious stimulation. Single neuronal activity was recorded with a carbon-filament electrode at the lumbosacral enlargement of cat spinal cord. After identifying WDR cells, their responses to peripheral noxious mechanical or thermal stimuli were characterized and the effects of SOM and Mor, applied either iontophoretically or intrathecaly, were studied. In most cells SOM and Mor suppressed noxious stimulus-evoked WDR neuronal activity, though a few WDR neurons showed no change or were excited by SOM and Mor. Systematically applied naloxone, a non-specific opioid antagonist, always reversed the Mor induced suppression of neuronal activity evoked by novious mechanical stimuli, but did not always reverse the suppression of neuronal activity elicited by SOM. The suppressive effect of Mor on thermal stimulus- evoked neuronal activity was partially reversed by naloxone, while that of SOM were not reversed at all. The above results suggest that both Mor and SOM exert an inhibitory effect on thermal and mechanical stimulus-evoked WDR neuronal activity in cat spinal dorsal horn, but the mechanisms are dependent upon the functional populations of dorsal horn nociceptive neurons.

Original languageEnglish (US)
Pages (from-to)155-163
Number of pages9
JournalKorean Journal of Physiology and Pharmacology
Volume2
Issue number2
StatePublished - Jan 1 1998

Keywords

  • Mechanical and thermal noxious stimuli
  • Morphine
  • Naloxone
  • Somatostatin
  • WDR cells

ASJC Scopus subject areas

  • Physiology
  • Pharmacology

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