Influence of intracerebroventricular administration of cannabinergic drugs on morphine state-dependent memory in the step-down passive avoidance test.
The effects of cannabinergic drugs on morphine state-dependent memory of passive avoidance task were examined in mice. Pre-training (0.25, 0.5 and 5 mg/kg) and post-training (5 mg/kg) administration of morphine impaired memory retrieval on the test day. Impairment of memory retrieval by morphine (5 mg/kg) on the test day was reversed by pre-test administration of the same dose of the opioid. The pre-test intracerebroventricular administration of the cannabinoid CB1/CB2 receptor agonist (WIN55,212-2) (0.75 and 1 microg/mouse) not only mimicked the effect of pre-test morphine treatment, but also increased this action of the opioid. Furthermore, the pre-test intracerebroventricular administration of CB1 receptor antagonist (AM251) (20 and 100 ng/mouse) prevented the restoration of memory by morphine. Pre-training administration of WIN55,212-2 (1 microg/mouse) led to state-dependent learning with impaired memory retrieval on the test day as well, which was reversed by pre-test administration of the drug (0.5, 0.75 and 1 microg/mouse) or morphine (1 and 5 mg/kg). Restoration of impairment induced by WIN55,212-2 was decreased by both the opioid receptor antagonists, naloxone (0.01 microg/mouse) and AM251 (20 and 100 ng/mouse). In conclusion, the improvement of memory retrieval by morphine treatment on the test day seems to be induced, at least in part, by the cannabinoid CB1 receptors.
Zarrindast
Mohammad-Reza
MR
Department of Pharmacology, School of Medicine and Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, Tehran, Iran. zrrndst@yahoo.com
Kangarlu-Haghighi
Katayoun
K
Khalilzadeh
Azita
A
Fazli-Tabaei
Soheila
S
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D048588:Benzoxazines; D007276:Injections, Intraventricular; D008297:Male; D008568:Memory / Q000187:drug effects*; D051379:Mice; D009020:Morphine / Q000494:pharmacology*; D009025:Morpholines / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D043884:Receptor, Cannabinoid, CB1 / Q000819:agonists* / Q000037:antagonists & inhibitors*
D000701:Analgesics, Opioid; D048588:Benzoxazines; D009025:Morpholines; D009281:Naphthalenes; D009292:Narcotic Antagonists; D010880:Piperidines; D011720:Pyrazoles; D043884:Receptor, Cannabinoid, CB1; D009270:Naloxone; C103505:AM 251; C070417:(3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone; D009020:Morphine