The effects of training and detraining on memory, neurotrophins and oxidative stress markers in rat brain.

In the current investigation we tested how swimming training (T) (8 week, 5 times/week, 2 h/day), and detraining (DT) affects brain functions and oxidative stress markers in rat brain. The free radical concentration, measured by electron paramagnetic resonance, decreased in brain of T and DT rats compared to controls (C). The level of brain-derived neurotrophic factor (BDNF) increased as a result of training, but decreased below the control level after 6 weeks of detraining. In addition, the concentration of nerve growth factor (NGF) also declined with DT. The passive avoidance test was used to assess the memory of rats, and training-induced improvement was observed but the enhancement disappeared with detraining. When the content of mitochondrial electron transport complexes, as a potent free radical generator, was evaluated by the blue native gel method, no significant alterations were observed. The repair of nuclear and mitochondrial 8-oxodeoxyguanosine, as measured by the activity of OGG1, showed no significant difference. Therefore, the results suggest that regular exercise training improves memory, decreases the level of reactive oxygen species, and increase the production of BDNF and NGF. On the other hand, it appears that the beneficial effects of training are reversible in the brain, since detraining down-regulates the neurotrophin level, and memory. It is suggested that exercise training is more likely to beneficially effect the production of reactive oxygen species and the related oxidative damage.