Pretreatment with pertussis toxin blocks morphine- but not beta-endorphin-induced antinociception in the mouse.
We have previously demonstrated that the antinociception induced by morphine and beta-endorphin given intracerebroventricularly (i.c.v.) is mediated by the stimulation of respective mu- and epsilon-opioid receptors. The effects of i.c.v. pretreatment with pertussis toxin on the antinociception induced by morphine and beta-endorphin given i.c.v. were studied in male ICR mice. Antinociception was assessed by the tail-flick and hot-plate tests. Pretreatment with pertussis toxin (0.5 microgram) given i.c.v. 96 h earlier blocks the antinociception induced by i.c.v. administered morphine in both tail-flick and hot-plate tests. The same pretreatment did not affect the antinociception induced by i.c.v. administered beta-endorphin. Our results indicate that morphine-, but not beta-endorphin-induced antinociception is mediated by pertussis toxin sensitive G-proteins.
Tseng
L F
LF
Department of Anesthesiology, Medical College of Wisconsin, Milwaukee 53226, USA. ltseng/post.its.mcw.edu
Collins
K A
KA
D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D019204:GTP-Binding Proteins / Q000378:metabolism; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009020:Morphine / Q000008:administration & dosage / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D010147:Pain Measurement / Q000187:drug effects; D037342:Pertussis Toxin; D051381:Rats; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*; D001615:beta-Endorphin / Q000008:administration & dosage / Q000037:antagonists & inhibitors* / Q000494:pharmacology
D000701:Analgesics, Opioid; D010566:Virulence Factors, Bordetella; D001615:beta-Endorphin; D009020:Morphine; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins