title: Effects of pre-training morphine on spatial memory acquisition and retrieval in mice.
abstract: The opioid system plays an important role in memory processess. Morphine mimics endogenous opioids by acting on opioid receptor in brain to regulate memory. However, the effects of morphine on spatial memory acquisition are controversial. Also, little evidence has suggested that morphine could affect the retrieval of spatial memory. In the current study, effects of pre-training morphine and naloxone on the acquisition vs. retrieval of spatial reference vs. working memory were examined using discrete water maze tasks in C57BL/6 mice. Pre-training morphine administration (7.5 and 15 mg/kg, i.p.) impaired the acquisition of both spatial reference memory and working memory. Motivation to escape from the water maze was not affected by morphine. Pre-test morphine also inhibited the retrieval of spatial working memory but not reference memory. The effects of morphine on the acquisition and retrieval of spatial working memory were eliminated by naloxone pretreatment (1mg/kg). These results indicate that morphine could differentially modulate a variety of aspects of spatial memory and these effects are mediated by the mu-opioid receptor.
authors.affiliation: Forensic Department, Xi'an Jiaotong University Medical College, Xi'an, PR China.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
authors.forename: Chun-xia
authors.initials: CX
authors.lastname: Yan
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhao
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.forename: Ping-ping
authors.initials: PP
authors.lastname: Li
authors.forename: Sheng-bin
authors.initials: SB
authors.lastname: Li
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D003216:Conditioning, Operant / Q000187:drug effects*; D003463:Cues; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005106:Exploratory Behavior / Q000187:drug effects; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D011939:Mental Recall / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D009020:Morphine / Q000494:pharmacology*; D009042:Motivation / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D011930:Reaction Time / Q000187:drug effects; D013028:Space Perception / Q000187:drug effects*; D013997:Time Factors
chemical_list: D009292:Narcotic Antagonists; D009294:Narcotics; D009270:Naloxone; D009020:Morphine