Background: Aging is often accompanied by cognitive decline, memory impairment and an increased susceptibility to neurodegenerative disorders. Although physiological processes of the
aging are not fully understood, these age-related changes have been interpreted from perspective of various cellular and molecular theories. Among these theories, alterations in the intracellular
signaling pathways associated to cell growth, proliferation and survival have been highlighted. Based on these observations and on recent evidence showing the beneficial effects of exercise on
cognitive function in elderly, we investigated the cell signaling pathways in hippocampal formation of aged rats submitted to treadmill exercise over 10 days. To do so, we evaluated the hippocampal
activation of intracellular signaling pathways linked to cell growth, proliferation and survival, such as protein kinase B (Akt), mammalian target of rapamycin (mTOR), p70 ribosomal protein S6 kinase
(p70S6K), extracellular signal-regulated protein kinase (ERK), cAMP response element-binding protein (CREB), and p38 mitogen-activated protein kinase (p38). Additionally, we explored the cognitive
performance (inhibitory avoidance) of aged rats.
Methods: Eighteen month-old male Wistar rats (n=36) were divided into two groups: exercise (n=20) and control (n=16). Aged rats from the exercise group were submitted to aerobic
physical exercise in a treadmill (15 m/min over 30 min per day) during 10 consecutive days. After last section exercise, aged rats from all groups were randomly selected to analyze the hippocampal
activation and expression of Akt, mTOR, p70S6K, ERK, CREB and p38, and the cognitive performance by mean of inhibitory avoidance task (aversive memory).
Results: It was found that the physical exercise reduces p38 activation in the hippocampal formation of aged rats, when compared to the control group. The hippocampal activation and
expression of Akt, mTOR, p70S6K, ERK and CREB were not statistically different between the groups. It was also observed that aged rats from exercise group exhibited better cognitive performance in
inhibitory avoidance task (aversive memory) than did aged rats from control group.
Conclusions: Our results indicate that physical exercise reduces intracellular signaling pathways linked to inflammation and cell death (p38) and improves learning and memory of aged