The Effect of Synchronized Running Activity with Chronic Stress on Passive Avoidance Learning and Body Weight in Rats

BACKGROUND: Different stressors induce learning and memory impairment and physical activity influence learning and memory enhancement. In this research, we investigated the effect of synchronized running activity with stress on acquisition and retention time of passive avoidance test. METHODS: Male Wistar rats were randomly divided into five groups as follows: Control (Co), Sham (Sh), Exercise (Ex), Stress (St), synchronized exercise with stress (St and Ex) groups. Chronic restraint stress was applied by 6 h/day for 21 days and treadmill running 1 h/day for 21 days. For evaluation of learning and memory, initial and step-through latency were determined at the end of study by using passive avoidance learning test. RESULTS: Our results showed that: (1) Exercise under no stress provides beneficial effects on memory acquisition and retention time compared to Control group; especially retention time had significantly (P < 0.05) increased in exercised group. (2) Chronic stress with and without synchronized exercise significantly (P < 0.01, P < 0.05, respectively) impaired acquisition and retention time. (3) Body weight differences were significantly (P < 0.01, P < 0.001 and P < 0.001) lower than Control group in exercise, stress and synchronized exercise with stress groups, respectively. (4) Adverse effects of restraint stress (psychical stress) were probably greater than physical activity effects on learning, memory and weight loss. CONCLUSIONS: The data confirmed that synchronized exercise with stress had not significantly protective role in improvement of passive avoidance acquisition and retention time; hence it did not significantly improve learning and memory deficit in stressed rats; whereas exercise alone could improve memory deficit in rats.