Intrathecal pertussis toxin but not cyclic AMP blocks kappa opioid-induced antinociception in rat

Int J Neurosci. 1995 Apr;81(3-4):193-7. doi: 10.3109/00207459509004886.


The role of inhibitory G-proteins and cyclic AMP in spinal mechanisms of kappa opioid receptor-mediated antinociception was assayed by recording the withdrawal response latency of the rat tail following immersion into a water bath of 49 degrees C. Intrathecal administration of pertussis toxin (1 microgram/rat, five days before the behavioral evaluation) prevented the antinociceptive effect of the kappa receptor agonist U-50,488H, while administration of dibutyryl cyclic AMP (10 micrograms/rat, 17 min. after U-50,488H) did not antagonize the antinociceptive action of the kappa ligand. Results suggest that in the spinal cord the signal transduction mechanism subserving the antinociceptive effect of U-50,488H involves a Gi or Go protein, but also that cyclic AMP is not implicated in coupling Gi/Go proteins to the effector system.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cyclic AMP / pharmacology*
  • Injections, Spinal
  • Nociceptors / drug effects*
  • Pain / drug therapy
  • Pertussis Toxin*
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Opioid, kappa / drug effects*
  • Spinal Cord / drug effects
  • Time Factors
  • Virulence Factors, Bordetella / administration & dosage*
  • Virulence Factors, Bordetella / pharmacology*


  • Receptors, Opioid, kappa
  • Virulence Factors, Bordetella
  • Cyclic AMP
  • Pertussis Toxin