Intracerebroventricular treatment of mice with pertussis toxin induces hyperalgesia and enhances 3H-nitrendipine binding to synaptic membranes: similarity with morphine tolerance.
The effect of intracerebroventricular treatment of mice with pertussis toxin (PTX) on pain perception and 3H-nitrendipine binding was examined to study a possible change in the GTP-binding proteins in morphine tolerant rodents. It was observed that both PTX treatment and chronic administration of morphine cause hyperalgesia in the acetic acid-induced writhing test. Analgesic effects brought by the acute administration of morphine or nifedipine, a calcium antagonist, were not affected by PTX treatment. In synaptic membrane fractions prepared from mice treated with PTX or morphine chronically, specific binding of 3H-nitrendipine was enhanced approximately 41.8% and 35.7%, respectively, without alteration in its affinity. Chronic administration of morphine followed by PTX treatment did not display further increases in 3H-nitrendipine binding. These results suggest that the PTX-sensitive GTP-binding proteins may not be involved in the manifestation of the analgesic effect of morphine in mice.
Ohnishi
T
T
Second Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Osaka University, Suita, Japan.
Saito
K
K
Maeda
S
S
Matsumoto
K
K
Sakuda
M
M
Inoki
R
R
D000085:Acetates; D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D004361:Drug Tolerance; D019204:GTP-Binding Proteins / Q000378:metabolism; D066298:In Vitro Techniques; D007276:Injections, Intraventricular; D008297:Male; D008566:Membranes / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D009020:Morphine / Q000494:pharmacology*; D009568:Nitrendipine / Q000378:metabolism*; D010146:Pain / Q000139:chemically induced* / Q000503:physiopathology; D010147:Pain Measurement; D037342:Pertussis Toxin; D013570:Synaptic Membranes / Q000187:drug effects / Q000378:metabolism*; D010566:Virulence Factors, Bordetella / Q000008:administration & dosage / Q000494:pharmacology*
D000085:Acetates; D010566:Virulence Factors, Bordetella; D009020:Morphine; D009568:Nitrendipine; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins