Discrepancy between effects of milligram and nanogram doses of a COX-2 inhibitor (celecoxib) on morphine state-dependent memory of passive avoidance in mice.
This experiment examined and compared the effects of pre-test administration of a selective COX-2 inhibitor (celecoxib), at the doses in the range of mg/kg and ng/kg on morphine state-dependent learning in step-down passive avoidance task in mice. Pre-training administration of 5mg/kg of morphine-impaired memory retrieval tested 24h later, which was restored by pre-test administration of the same dose of the drug. Pre-test administration of celecoxib (12.5, 25 and 50mg/kg), alone or in combination with morphine (1mg/kg) prevents morphine-induced memory impairment. Ultra-low doses (ULDs) of celecoxib (2, 10 and 50 ng/kg) produced no change in morphine-induced memory impairment. However, co-administration of nanogram doses of celecoxib with 5mg/kg of morphine in the test day prevented morphine-induced memory improvement, an action different from mg/kg doses. These findings implicate the involvement of COX-2 in memory retrieval and demonstrate that the effect of celecoxib ULD is different from that of mg/kg doses.
Khalilzadeh
A
A
Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, P.O. Box 13145-134, Tehran, Iran.
Tayebi Meybodi
K
K
Vakili Zarch
A
A
Zarrindast
M R
MR
Djahanguiri
B
B
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D000068579:Celecoxib; D052246:Cyclooxygenase 2 Inhibitors / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D008297:Male; D008568:Memory / Q000187:drug effects*; D008569:Memory Disorders / Q000139:chemically induced; D051379:Mice; D009020:Morphine / Q000494:pharmacology*; D011720:Pyrazoles / Q000008:administration & dosage*; D013449:Sulfonamides / Q000008:administration & dosage*
D000701:Analgesics, Opioid; D052246:Cyclooxygenase 2 Inhibitors; D011720:Pyrazoles; D013449:Sulfonamides; D009020:Morphine; D000068579:Celecoxib