The Time-Course of the Effects of Stress on Behavior in Rodents

Acute stress has been shown to have facilitating effects on memory tasks while chronic stress can enhance the development of psychiatric disorders such as depression and anxiety disorders. It is currently unknown how much stress is required to create these debilitating effects. This study is the first step in examining the time-course of the effects of stress in rodents. Anxiety-like behavior in the Elevated Plus Maze (EPM) and fear memory in Pavlovian conditioning using cued fear conditioning were examined after one or seven days of restraint stress. After seven days of restraint stress there was a decrease in anxiety-like behavior in the EPM, compared to rats exposed to a single session of stress. These results suggest the importance of the time delay between stress and behavioral testing. No significant results were seen in cued fear conditioning. To assess whether this effect is similar in males and females, anxiety-like behavior was measured in female rats after one day of restraint stress. No difference was found between female control and stress rats. These results suggest that females were not more vulnerable to the effects a single restraint stress on the EPM.