title: Dexamethasone reduces morphine-induced Straub reaction in mice.
abstract: This study examined the effect of dexamethasone on morphine-induced straub reaction in mice. When morphine was administered in doses of 7.5, 15 and 30 mg kg(-1) intraperitoneally, a dose-dependent straub reaction was produced. Dexamethasone per-se (0.1-10 mg kg(-1) i.p.) did not modify the tail of control mice. Pre-treatment with dexamethasone 120 min before morphine injection caused a dose-dependent reduction of straub reaction. Cycloheximide (15 mg kg(-1) i.p.) administered 2 h before morphine did not change morphine-induced straub reaction, but was able to prevent the effects of dexamethasone on morphine-induced straub reaction. The glucocorticoid receptor antagonist RU-38486 (15 mg kg(-1) i.p.) did not affect morphine-induced straub reaction, whereas it was able to block the effects of dexamethasone on morphine-induced straub reaction. Results of this study indicate that dexamethasone reduced morphine-mediated straub reaction in mice, indicating a further important functional interaction between dexamethasone and the opioid system. The ability of cycloheximide and RU-38486 to block dexamethasone's effects indicates that the steroid's interference with morphine-mediated straub reaction involves a protein-synthesis-dependent mechanism via glucocorticoid receptors.
authors.affiliation: Department of Pharmaceutical Sciences, University of Salerno, Fisciano, Italy. annacap@unisa.it
authors.forename: Anna
authors.initials: A
authors.lastname: Capasso
authors.forename: Carmela
authors.initials: C
authors.lastname: Casciano
authors.forename: Alberto
authors.initials: A
authors.lastname: Loizzo
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006727:Hormone Antagonists / Q000494:pharmacology; D007263:Infusions, Parenteral; D051379:Mice; D015735:Mifepristone / Q000494:pharmacology; D009020:Morphine / Q000009:adverse effects*; D009068:Movement / Q000187:drug effects*; D009294:Narcotics / Q000009:adverse effects*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000502:physiology; D013623:Tail
chemical_list: D000893:Anti-Inflammatory Agents; D006727:Hormone Antagonists; D009294:Narcotics; D011500:Protein Synthesis Inhibitors; D011965:Receptors, Glucocorticoid; D015735:Mifepristone; D009020:Morphine; D003907:Dexamethasone; D003513:Cycloheximide