Central interaction of dexamethasone and RU-38486 on morphine antinociception in mice.
The central interference induced by dexamethasone and RU-38486, (a glucocorticoid receptor antagonist) on morphine antinociception were studied by using the tail flick test in mice. Dexamethasone, injected intracerebrally (i.c.v.) 10 minutes before morphine, dose-dependently reduced morphine antinociception, whereas RU-38486 which was injected with the same lag time, potentiated it. When dexamethasone and RU-38486 were administered together i.c.v., 10 minutes before morphine, an overall reduction of morphine antinociception was observed, similar to that observed with dexamethasone pretreatment only. The present results strongly suggest a central site of interaction for dexamethasone and RU-38486 on morphine antinociception; the short latency and the dose-related slope for this interaction may suggest a mechanism at least in part different from the glucocorticoid-induced genomic activation.
Capasso
A
A
Department of Experimental Pharmacology, University of Naples Federico II, Italy.
Di Giannuario
A
A
Loizzo
A
A
Pieretti
S
S
Sorrentino
L
L
D000818:Animals; D001921:Brain / Q000187:drug effects*; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology*; D004347:Drug Interactions; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D015735:Mifepristone / Q000008:administration & dosage / Q000494:pharmacology*; D009020:Morphine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D010147:Pain Measurement
D015735:Mifepristone; D009020:Morphine; D003907:Dexamethasone