Dexamethasone reduced clonidine-induced hypoactivity in mice.
Reduced clonidine anti-nociception in mice given low doses of dexamethasone has encouraged us to investigate the effects of dexamethasone pretreatment on locomotor hypoactivity, another example of clonidine-induced behaviour in mice. Dexamethasone administered intraperitoneally (0.1, 1.0, 10 mg kg-1) 30 min before clonidine reduced clonidine-induced locomotor hypoactivity in the activity cage to an extent which was dose-dependent. Dexamethasone administered centrally (10 ng/mouse) 30 min before clonidine was also able to reduce clonidine-induced locomotor hypoactivity. Cycloheximide administered at a dose of 10 mg kg-1 2 h before clonidine did not change the effects of clonidine but was able to prevent the effects of dexamethasone on clonidine-induced hypoactivity. The glucocorticoid receptor antagonist RU38486 administered centrally at the dose of 1 ng/mouse did not change the effects of clonidine, whereas it was able to block the effects of dexamethasone on clonidine-induced locomotor hypoactivity. These results suggest that the effects of dexamethasone on clonidine-induced locomotor hypoactivity depend on the stimulating effects that dexamethasone exerts on the protein synthesis via the glucocorticoid receptor in the brain.
Capasso
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A
School of Pharmacy, University of Salerno, Italy.
Di Giannuario
A
A
Loizzo
A
A
Pieretti
S
S
Sorrentino
L
L
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D003907:Dexamethasone / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005938:Glucocorticoids / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D006727:Hormone Antagonists / Q000494:pharmacology; D007274:Injections, Intraperitoneal; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D015735:Mifepristone / Q000494:pharmacology; D009043:Motor Activity / Q000187:drug effects*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D005938:Glucocorticoids; D006727:Hormone Antagonists; D011500:Protein Synthesis Inhibitors; D015735:Mifepristone; D003907:Dexamethasone; D003513:Cycloheximide; D003000:Clonidine