Resumo

Physical exercise is neuroprotective and enhances brain function by improving cognition, learning and memory. Exercise has also been associated with structural changes in the brain such as angiogenesis, synaptogenesis and neurogenesis. However, it remains unclear which effects can be achieved with each of the various protocols that have been proposed. The aim of this study was to evaluate the acute plastic effects of a moderate short-term forced exercise protocol on synaptic proteins, such as synapsin (SYN) and synaptophysin (SYP), trophic factors such as brain-derived neurotrophic factor (BDNF), and structural proteins such as neurofilaments (NFs), microtubule-associated protein 2 (MAP-2) and glial fibrillary acidic protein (GFAP) in brain regions related to motor function and commonly affected by neurodegenerative diseases. Real-time PCR was used to study these changes in the cerebellum, sensory-motor cortex, substantia nigra, striatum and reticular formation. Adult male Wistar rats (±250g) were adapted to a treadmill and divided into 4 groups: sedentary (S), 3 day-exercise (EX3), 7 day-exercise (EX7) and 15 day-exercise (EX15). The exercise program consisted of treadmill running at 10m/min, 0 degree inclination, for 40 min/day for 3, 7 and 15 consecutive days. In the analysis of the cerebellum, we observed no changes of mRNA expression. The analysis of the substantia nigra, however, revealed significant increases of mRNA for SYN at EX3 (p<0.05) and EX7 (p<0.01) and for SYP at EX3 (p<0.001). There was also an increase of NF68 mRNA at EX3 (p<0.05), and increases of BDNF, MAP2 and GFAP mRNA at EX3 and EX7 (p<0.05), EX3 (P<0.05) and EX3 and EX15 (p<0.05), respectively. In the striatum, there was a statistically significant increase of SYN mRNA at EX3 (p<0.05) accompanied by decreases of SYP mRNA at EX15 (p<0.05), NF68 mRNA at EX7 (p<0.05) and EX15 (p<0.01) and NF200 mRNA at EX15 (p<0.05). Additionally, we observed increased MAP2 and GFAP mRNA at EX3 and EX7 respectively (p<0.05). In the cortex, we observed decreased BDNF mRNA at EX3 (p<0.05) and GFAP mRNA at all exercise periods (p<0.001). As for the reticular formation, we observed increases of NF68 mRNA at EX7 (p<0.05) and NF160 mRNA at all exercise periods (p<0.05, p<0.001, p<0.01), along with increased BDNF mRNA at EX3 (p<0.001) and decreased GFAP mRNA at all exercise periods (p<0.05, p<0.001, p<0.01). These results suggest that physical exercise of moderate intensity is enough to modulate synaptic and structural elements of neurons as well as astrocytes, playing an important role in the diffuse exercise-dependent plasticity of brain regions related to motor control.