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


RESULTS
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of memory after 1 h ITI. 3) Morphine 5 and 10 mg/kg caused hyper-locomotor activity depending on the state. 4) Mice withdrawn from morphine 40 mg/kg but not 10 mg/kg for 3 days showed amnesia in Y-maze.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.
Ma
M X
MX
Department of Psychology, Jilin University, Changchun, 130012, PR China.
Chen
Y M
YM
He
J
J
Zeng
T
T
Wang
J H
JH
D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D051379:Mice; D008813:Mice, Inbred ICR; D009020:Morphine / Q000008:administration & dosage*; D009021:Morphine Dependence / Q000503:physiopathology*; D009294:Narcotics / Q000008:administration & dosage*; D021641:Recognition, Psychology / Q000187:drug effects*; D013037:Spatial Behavior / Q000187:drug effects*; D013997:Time Factors
D009294:Narcotics; D009020:Morphine