Background: It has been observed in human and animal studies that environmental stimuli such as physical activity seem to have a favourable influence on postnatal brain development.
Indeed, enhanced cognitive performance has been noted in individuals who were physically active during childhood and adolescence. In animal studies, it has also reported that early-life exercise
improves the cognitive function of developing rats. The mechanisms by which juvenile exercise promotes such effects in the brain are just starting to be elucidated. One possible explanation in favour
of the beneficial effect of physical activity early in life is that it enables better neural development. Probably, this better neural development occurs by activation of intracellular signaling
pathways associated to cell growth, proliferation and survival. Based on this observation, the present study was designed to evaluate the number of neuronal and non-neuronal cells and the expression
and activation of intracellular proteins (Akt, mTOR, p70S6K, ERK e CREB) in the cortex and hippocampal formation of adolescent rats submitted to an aerobic exercise program.
Methods: Male Wistar rats aged 21 postnatal days old (P21) were divided into two groups: exercise (n=10) and control (n=10). Animals in the exercise group were submitted to daily
exercise on the treadmill between P21 and P60. After the aerobic exercise program (P60), it was investigated the number of neuronal and non-neuronal cells and the expression and activation of Akt,
mTOR, p70S6K, CREB and p38 (total and phosphorylated) in the cortex and hippocampal formation of rats from the exercise and control groups. To quantify the number of cells, we used the isotropic
fractionation method. To investigate the intracellular signaling pathways, we used MAGPIX® technology.
Results: Our results showed that juvenile exercise increased the cortical number of neuronal and non-neuronal cells and the hippocampal number of neuronal cells. Furthermore, it was
observed an overexpression of total mTOR protein and an overactivation of Akt protein in cortical region of rats from exercise group in relation to control group.
Conclusions: These findings indicate that physical exercise can increase cortical expression and activation of intracellular proteins linked to cell proliferation and survival (mTOR
and Akt) and rise absolute number of neuronal cells in the cortex and hippocampal formation of developing rats.