Title: THE STUDY OF IMPACT OF STRESS AND ENVIRONMENT ON ELECTROPHYSIOLOGY AND BEHAVIOR CHANGES IN MORPHINE-EXPOSED RATS
Abstract: Objective: To study the effect of stress and acute morphine exposure on synaptic plasticity of hippocampal CA1 area and spatial memory in rats of different ages;to study the effects of enriched environment(EE) on spatial learning and memory and morphine induced conditioned place preference(CPP) of Wistar rats,to explore if EE can affect synaptic plasticity on normal and addicted rats.Methods: Electrophysiological technique in vivo and in vitro and behavioral test including Morris water maze and CPP were used in this study.Statistical analysis was made using ANOVA or Student's t-test. Results and conclusions:(1) Chronic stress and morphine had different effects on LTP and LTD in(4-and)-10-week-old rats and it showed significant difference between the two age groups of rats.LTP and LTD were facilitated in chronic stress and morphine group of 4-week-old rats;LTP was impaired and LTD was completely inhibited in the same group of 10-week-old rats.(2) Acute EP stress induced impairment of memory retention in 4-or 10-week-old rats,respectively,but it did not differ between 4-week-old rats and 10-week-old rats.Chronic EP stress induced enhancement of memory retention in 10-week-old rats and had no effect on memory retrieval in 4-week-old rats.(3) Morphine at the dose of 2 mg·kg~(-1) induced impairment of memory retention in 4-week-old rats and had no effect on memory retention in 10-week-old rats.(4) Acute EP stress and morphine induced impairment of memory retention in 4-week-old rats and had no effect on memory in 10-week-old rats.Chronic stress and morphine had no effect on memory retention in 4-week-old rats and induced enhancement of memory retention in 10-week-old rats.(5)EE enhanced morphine induced CPP,possibly due to the increased spatial learning and memory;and the synaptic plasticity impairments induced by morphine addiction can be attenuated by EE,suggest that EE may be helpful in protecting synaptic plasticity from opioids induced impairments.EE can reverse the impairment of early stress on spatial learning and synaptic plasticity.
Publication Year: 2006
Publication Date: 2006-01-01
Language: en
Type: article
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