Fish oil supplementation reverses behavioral and neurochemical alterations induced by swimming exercise in rats

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Diet and exercise are known to affect learning and memory. However, the effects of these interventions in the brain under development remains to be better investigated as the effects of high-intensity exercise. Moreover, it is still unclear how long the influence of diet and exercise lasts after the interventions are ceased. To investigate this, juvenile Wistar rats (30 days old) were supplemented with fish oil rich in polyunsaturated fatty acids (PUFAs) and performed swimming training for 50 days, 45 min per day, 5 times/week. The animals were assessed for locomotor activity with the open field test and for spatial memory with the object location task. To investigate neurochemical parameters such as fatty acids incorporation within the plasma membrane and brain-derived neurotrophic factor (BDNF) levels, the animals were euthanized, and the hippocampus dissected. These investigations were made at the end of the supplementation and exercise protocols and 21 days after the protocol has ended. Results indicate that high-intensity exercise impaired the spatial memory and decreased the levels of BDNF. Although supplementation led to PUFAs incorporation in plasma membrane, it did not prevent the harmful effect of exercise on memory. After 21 days of interruption, we observed that the supplementation reversed not only the deleterious effect of exercise on memory but also increased the BDNF levels. These results point to a complex influence of diet and exercise on spatial memory of juvenile rats, persisting after 21 days of interruption.