Effects of Acute Stress and Acute Morphine Exposure on Spatial Memory in Rats of Different Ages

Objective: To study the effects of acute stress and acute morphine exposure(2mg/kg) on spatial memory in 4-or 10-week-old rats.Methods: Morris water maze was used to assess the effects of acute stress(established by elevated platform stress protocol) and acute morphine exposure on spatial memory in 4-or 10-week-old rats.Results: ① 4-week-old rats: Rats of acute stress group,acute stress and morphine group and morphine group spent significantly less time in the target quadrant than that of control group,respectively(P0.05).②10-week-old rats: Rats of acute stress group spent significantly less time in the target quadrant than that of control group(P0.05).Compared with control group time in the target quadrant did not differ in acute stress plus morphine group,morphine group(P 0.05).③Comparison between 10-week-old rats and 4-week-old rats:10-week-old rats in morphine group,acute stress plus morphine group spent significantly more time in the target quadrant than that of 4-week-old rats in the same groups,respectively(P0.05).Time in the target quadrant did not differ in acute stress group and control group between 4-week-old rats and 10-week-old rats(P 0.05).Swimming speed did not differ between all groups of 4-or 10-week-old rats(P 0.05).Conclusion: ①Acute stress induced impairment of memory retention in 4-or 10-week-old rats,respectively;but it did not differ between ages.②Acute morphine exposure at the dose of 2mg/kg induced impairment of memory retention in 4-week-old rats and had no effect on memory retention in 10-week-old rats.It showed difference between two age groups.③Acute stress plus morphine induced impairment of memory retention in 4-week-old rats and had no effect on memory in 10-week-old rats.It showed difference between two age groups.