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Neuroscience. 2007 Jul 29;147(4):1059-65. Epub 2007 Jul 2.

Effects of morphine and its withdrawal on Y-maze spatial recognition memory in mice.

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Department of Psychology, Jilin University, Changchun, 130012, PR China.


Effects of morphine on acquisition and retrieval of memory have been proven in the avoidance paradigms. In present study, we used a two-trial recognition Y-maze to test the effects of acute morphine and morphine withdrawal on spatial recognition memory. The Y-maze is based on the innate tendency of rodents to explore novel environments and therefore avoid punishment and reward.


1) Pre-training morphine 10 mg/kg impaired the recognition spatial memory of acquisition after a 1 h inter-trial interval (ITI), whereas morphine 2.5, 5 and 10 mg/kg showed impairment after 2 h ITI. 2) Pre-retention morphine 5, 10 mg/kg disrupted the retrieval of memory after 1 h ITI. 3) Morphine 5 and 10 mg/kg caused hyper-locomotor activity depending on the state. 4) Mice withdrawn from morphine 40 mg/kg but not 10 mg/kg for 3 days showed amnesia in Y-maze. Our data suggested that acute morphine impaired the acquisition and retrieval of spatial recognition memory and increased the locomotor activity in the Y-maze depending on the dose and state. Moreover, withdrawal from chronic morphine also impaired acquisition in the Y-maze depending on the dose and state.

[Indexed for MEDLINE]

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