RU 486 reduces morphine-induced analgesia in mice, but steroid receptors are not involved.
The effects of subcutaneous pretreatment with the glucocorticoid/progesterone receptor antagonist RU 486 on the antinociceptive action of peripherally administered morphine were evaluated by the hot-plate test in mice. The steroid significantly reduced the analgesic effect of the opiate. Neither dexamethasone nor progesterone modified the effects of RU 486 on morphine-induced analgesia. Therefore, the present data indicate that the modulatory effect of RU 486 on morphine-induced analgesia does not involve the binding of this drug to classical steroid receptors.
Bianchi
M
M
Department of Pharmacology, University of Milano, Italy.
Maggi
R
R
Panerai
A E
AE
Martini
L
L
D000698:Analgesia; D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology; D004347:Drug Interactions; D007279:Injections, Subcutaneous; D008297:Male; D051379:Mice; D015735:Mifepristone / Q000008:administration & dosage / Q000494:pharmacology*; D009020:Morphine; D010147:Pain Measurement; D011374:Progesterone / Q000494:pharmacology; D011987:Receptors, Steroid / Q000187:drug effects / Q000502:physiology*
D011987:Receptors, Steroid; D015735:Mifepristone; D011374:Progesterone; D009020:Morphine; D003907:Dexamethasone