title: A pertussis toxin-sensitive G protein mediates inhibition by morphine of spontaneous electrical activity of oxytocin neurones in anaesthetized rats.
abstract: We investigated the effects of intracerebroventricular (i.c.v.) pertussis toxin upon the sensitivity of supraoptic oxytocin neurones to intravenous morphine (1-5000 micrograms/kg) in urethane-anaesthetized rats. The maximal inhibitory capacity of morphine was diminished by prior administration of pertussis toxin. Some cells were tested with both morphine and with the kappa-opioid agonist U50,488 (1-5000 micrograms/kg): U50,488-induced inhibition of firing rate was apparently unimpaired by pertussis toxin pre-treatment. The opioid inhibition of firing rate seen in the absence of and after pertussis toxin pre-treatment was naloxone-reversible. Thus a pertussis toxin-sensitive G protein may mediate the inhibitory action of morphine upon supraoptic putative oxytocin neurones or inputs to them.
authors.affiliation: Department of Physiology, University Medical School, Edinburgh, UK.
authors.forename: K M
authors.initials: KM
authors.lastname: Pumford
authors.forename: G
authors.initials: G
authors.lastname: Leng
authors.forename: J A
authors.initials: JA
authors.lastname: Russell
mesh_terms: D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000200:Action Potentials / Q000187:drug effects; D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007275:Injections, Intravenous; D008845:Microinjections; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010121:Oxytocin / Q000502:physiology*; D037342:Pertussis Toxin; D011759:Pyrrolidines / Q000494:pharmacology; D051381:Rats; D013495:Supraoptic Nucleus / Q000187:drug effects / Q000502:physiology*; D010566:Virulence Factors, Bordetella / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000700:Analgesics; D011759:Pyrrolidines; D010566:Virulence Factors, Bordetella; D010121:Oxytocin; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D009020:Morphine; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins