Enriched environment prevents chronic stress-induced spatial learning and memory deficits

Abstract

Chronic stress impairs spatial memory and alters hippocampal structure, which are changed in the opposite direction following enriched environment (EE). Therefore, this study incorporated these two paradigms to determine whether EE would prevent chronic stress from impairing spatial learning and memory. Young adult male rats were housed in EE for 1 week prior to and throughout 3 weeks of daily restraint stress. On the day after the end of restraint, rats were trained and tested on either a water maze (19 degrees C or 24 degrees C water temperature) or a spatial recognition Y-maze (4-h and 1-min delay between training and testing). Chronically stressed rats housed in standard conditions showed impaired acquisition on the 19 degrees C version of the water maze and deficits on the 4-h delay version of the Y-maze. Chronically stressed rats housed in EE, however, showed intact performance on all tasks. All rats showed intact performance on the 24 degrees C version of the water maze and on water maze probe trials for both versions. The results showed that EE in adulthood prevented spatial learning and memory impairment in chronically stressed rats, indicating that the context of stress exposure impacts susceptibility to chronic stress-induced cognitive deficits.

Assessment of estradiol influence on spatial tasks and hippocampal CA1 spines: Evidence that the duration of hormone deprivation after ovariectomy compromises 17β-estradiol effectiveness in altering CA1 spines

“…Previous research from our lab suggests that the traditional Y-maze task may be more sensitive to detecting changes in spatial memory of male rats relative to female rats (Conrad et al, 1996;Conrad et al, 2003;Kleen et al, 2006;McLaughlin et al, 2005;McLaughlin et al, 2007;Wright and Conrad, 2005;Wright et al, 2006;Wright and Conrad, 2008). Therefore, to make the task more challenging in this study, we modified the procedure to include longer delays (6 and 24 hours) than previously used (4 hours, Conrad et al, 1996;McLaughlin et al, 2007).…”

“…Water maze training included 4 trials per day for 2 days based upon a version used previously (Wright and Conrad, 2008). Rats swam for a maximum of 90s or until they located the escape platform.…”

The Effect of Exercise on Learning and Spatial Memory Following Stress-Induced Sleep Deprivation (Sleep REM) in Rats

“…Studies have shown that long-term stress can lead to cell death. It is believed that many of these structural changes following stress are involved in hippocampus function destruction, concerning spatial learning and memory, for example (4).…”

Experimentally Induced Hyperthyroidism Disrupts Hippocampal Long-Term Potentiation in Adult Rats

“…The percent of entries into a given arm was calculated as the ratio of entries into that arm to the total number of entries into the three arms. Spatial memory was indicated by increased entries into the novel arm during the retention trial [46,47,48]. …”