Basolateral amygdala CB1 cannabinoid receptors are involved in cross state-dependent memory retrieval between morphine and ethanol.
Ethanol and morphine are largely co-abused and affect memory formation. The present study intended to investigate the involvement of cannabinoid CB1 receptors of the basolateral amygdala (BLA) in cross state-dependent memory retrieval between morphine and ethanol. Adult male Wistar rats received bilateral cannulation of the BLA, and memory retrieval was measured in step-through type passive avoidance apparatus. Our results showed that post-training intraperitoneal (i.p.) administration of morphine (6mg/kg) induced amnesia. Pre-test administration of ethanol (0.5g/kg, i.p.) significantly improved morphine-induced memory impairment, suggesting that there is cross state-dependent memory retrieval between morphine and ethanol. It should be considered that pre-test administration of ethanol (0.1 and 0.5g/kg, i.p.) by itself had no effect on memory retrieval in the passive avoidance task. Interestingly, pre-test intra-BLA microinjection of different doses of WIN55,212-2 (0.1, 0.2 and 0.3μg/rat), a non-selective CB1/CB2 receptor agonist, plus an ineffective dose of ethanol (0.1g/kg, i.p.) improved morphine-induced memory impairment. Intra-BLA microinjection of AM251 (0.4-0.6ng/rat), a selective CB1 receptor antagonist, inhibited the improved effect of ethanol (0.5g/kg, i.p.) on morphine response. Pre-test intra-BLA microinjection of WIN55,212-2 or AM251 had no effect on memory retrieval or morphine-induced amnesia. Taken together, it can be concluded that morphine and ethanol can induce state-dependent memory retrieval. In addition, the BLA endocannabinoid system mediates via CB1 receptors the functional interaction of morphine and ethanol state-dependent memory retrieval which may depend on the rewarding effects of the drugs.
Department of Animal Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran.
Sattar Norouzi
SN
Ofogh
Department of Animal Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran. Electronic address: rezayof@khayam.ut.ac.ir.
Ameneh
A
Rezayof
Department of Animal Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran.
Maryam
M
Sardari
Department of Animal Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran.
Zahra
Z
Ghasemzadeh
D000818:Animals; D066272:Basolateral Nuclear Complex / Q000502:physiology*; D048588:Benzoxazines / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D008297:Male; D008568:Memory; D009020:Morphine / Q000494:pharmacology*; D009025:Morpholines / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D043884:Receptor, Cannabinoid, CB1 / Q000502:physiology*
D048588:Benzoxazines; D009025:Morpholines; D009281:Naphthalenes; D010880:Piperidines; D011720:Pyrazoles; D043884:Receptor, Cannabinoid, CB1; C103505:AM 251; D000431:Ethanol; 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
Basolateral amygdala; CB1 receptors; Ethanol; Memory retrieval; Morphine; Rat(s)