Resumo

Objectives: Evidence suggests the influence of treadmill exercise on some structural and functional brain aspects during senescence. The physical exercise can increase the levels of the proteins synapsin and synaptophysin, enhance neurogenesis and reduce the threshold for long-term potentiation. Furthermore, treadmill exercise and intensification of sensory stimulation during brain development (BD) can lastingly and/or transitorily change brain structure and functions. It has been previously demonstrated that sensory manipulation during BD can alter the propagation of cortical spreading depression (CSD; Nutr. Neurosci 3:29-40, 2000). Here we have investigated whether physical exercise during elderly could change cortical excitability as indexed by CSD. Methods: Wistar rats were randomly distributed 24 hours after birth to form litters with 6 pups, and suckled by dams receiving a standard lab-chow (23% protein, Labina, PURINA, Brazil). At 600 days of age, rats started receiving physical training sessions (five sessions per week, 30 min each session), during five weeks, in a motorized treadmill (Insight EP-131, 0º inclination), running at 5, 10 and 15 respectively in the 1st, 2nd and 3rd,training weeks and 25m/min for the 4th and 5th training weeks. Immediately after the 5-week exercise-period, CSD was recorded during 4 hours (Eletrocorticogram and slow potential changes) on 2 points of the cortical surface and CSD propagation velocity was calculated. Results: Trained rats (n=10) displayed lower CSD-velocities (2.57±0.26 to 2.69±0.45mm/min, mean ± standard deviation), when compared to a control group (2.76±0.26 to 2.94±0.26; n=10), consisting of rats submitted to the same training protocol, but with the treadmill turned off. Conclusion: Data indicate that treadmill exercise during senescence reduced CSD susceptibility, as judged by the lower CSD propagation rates, suggesting a role for sensory-motor activity in influencing cortical electrophysiological phenomena, like CSD. Financial support: PROPESQ-UFPE/CNPq. FACEPE. Manuella Oliveira é bolsista FACEPE. All procedures were approved by the Institutional Animal Care and Use Committee/UFPE, process nº 23076.021970/2008-77