Effect of Swimming Training on Spatial Memory of Maternal Deprived Infants: Inducing Stress by Six Hours Separation per Day

Primary stress can impair the nervous structure including the hippocampus and behavioral functions such as memory; therefore, paying attention to neutralizing the destructive effects of stress on the body has been one of the debatable topics among researchers. Considering the role of physical activity in reducing stress in previous studies, this study aimed to investigate the effect of four weeks of swimming training on learning and spatial memory in neonatal rats separated from their mother.

In this study, 40 male albino Wistar rats were randomly divided into four groups (separation from mother, separation from mother and swimming training, swimming training, and control). The method of separating the infants from the mothers was used to make stressful conditions. Rats from separation groups were separated from mothers 6 h per day starting from the day after birth for one month. For physical activity, swimming training was performed for four weeks (five sessions per week) incrementally to measure stress and blood glucose level in mice, and the Morris Water Maze test was used to assess the learning and spatial memory.

The results of the analysis of variance test showed that the blood glucose in the group of rats that were separated from their mothers was significantly higher, compared to the control group (P=0.045), indicating that stress was successfully induced in these rats. Moreover, the results of the multivariate analysis of the variance test showed that although stress had no significant impact on spatial learning, the results of the exploration test showed a significant decrease in the percentage of entering the target quadrant (P=0.05) and the time spent in the target quadrant in the group separated from mother (P=0.029), compared to the control group. Therefore, spatial memory was degraded due to stress in the group of rats that were separated from their mother, compared to the other groups. However, swimming training in the group of rats that was separated from the mother could neutralize the destructive effects of stress on spatial memory and the percentage of entering the target quadrant (P=0.02) as well as the time spent in the target quadrant (P=0.05).

The results showed that although stress did not have a negative impact on spatial learning, it had a destructive impact on memory. On the other hand, swimming training as a treatment method could largely neutralize the negative effects of stress and improve memory.