Investigating the effect of long-term unpredictable mild stress on anxiety, passive avoidance memory, depression-like behavior, and running index of male Wistar rats

Stress is a set of reactions that occurs in response to any factor that disturbs the internal balance (homeostasis). The present study aims to investigate the effect of unpredictable long-term stress on running index, passive avoidance memory, and depressive-like behaviors in male Wistar rats.

Sixteen male rats were randomly divided into two groups (Each group=8). The experimental group was exposed to four weeks of stress, while the control group was not under stress conditions. Forty-eight hours after the end of the intervention, behavioral and running index tests were taken from all animals. Rats’ body weight also were measured during the intervention induced. Data analysis was done using one-way and repeated measure analysis of variance. P˂0.05 was considered a significant change.

Chronic stress causes weight loss, increasing the time spent in the closed arm (plus elevated maze test), increasing the immobility time (forced swimming test), reducing the distance traveled in the open box test, reducing the distance traveled using the rotating wheel, increasing the number of times entering the black box (shuttle box test), increasing the duration of staying in the black box, and increasing the delay in entering the black box. Running distance had a negative correlation with stress and depression and had a positive correlation with memory and rats’ body weight.

Long-term stress negatively affects weight gain, anxiety, depression, memory, and running index of animals. According to the correlations, a better running index is associated with fewer behavioral disorders.