Intracellular GTP gamma S restores the ability of morphine to hyperpolarize rat locus coeruleus neurons after blockade by pertussis toxin.
The hyperpolarizing effect of morphine on locus coeruleus (LC) neurons, recorded with standard intracellular electrodes, was blocked in brain slices from rats pretreated with pertussis toxin, an inactivator of certain G proteins. In the same slices, when electrodes contained the hydrolysis-resistant GTP analog GTP gamma S, the ability of morphine to rapidly hyperpolarize LC neurons was restored and responses were similar in magnitude to those in control slices. We conclude that there is sufficient residual coupling between opiate receptors and G proteins after pertussis toxin treatment to allow the agonist to be effective when the hydrolysis-resistant GTP analog GTP gamma S is present.
D000818:Animals; D019204:GTP-Binding Proteins / Q000502:physiology; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology*; D008125:Locus Coeruleus / Q000166:cytology* / Q000187:drug effects; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009020:Morphine / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D037342:Pertussis Toxin; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D013873:Thionucleotides / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D011189:Potassium Chloride; D009020:Morphine; D006160:Guanosine Triphosphate; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins