Intrathecal pertussis toxin but not cyclic AMP blocks kappa opioid-induced antinociception in rat.
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.
Hernandez
A
A
Unit of Neurophysiology and Biophysics, University of Chile, Santiago.
Soto-Moyano
R
R
Mestre
C
C
Eschalier
A
A
Pelissier
T
T
Paeile
C
C
Contreras
E
E
D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology*; D007278:Injections, Spinal; D009619:Nociceptors / Q000187:drug effects*; D010146:Pain / Q000188:drug therapy; D037342:Pertussis Toxin; D051381:Rats; D017207:Rats, Sprague-Dawley; D017473:Receptors, Opioid, kappa / Q000187:drug effects*; D013116:Spinal Cord / Q000187:drug effects; D013997:Time Factors; D010566:Virulence Factors, Bordetella / Q000008:administration & dosage* / Q000494:pharmacology*
D017473:Receptors, Opioid, kappa; D010566:Virulence Factors, Bordetella; D000242:Cyclic AMP; D037342:Pertussis Toxin