Treadmill training effects in different age groups following middle cerebral artery occlusion in rats.

Background: Despite the increased understanding of treadmill training on stroke patients, its effects on different age groups are not clearly known. The present study presents such effects through a model of cerebral ischemia on young and old groups of rats.

Objectives: To investigate the effect of treadmill training on young and old rats after cerebral ischemia caused by middle cerebral artery occlusion (MCAO).

Methods: Forty old (22-24 months of age) and 32 young (3-4 months of age) rats underwent the MCAO procedure for 60 min. Rats that survived the procedure were randomly assigned to a 1- or a 2-week treadmill training group, or a time-matched control group (n=6-8 for each group). The infarct volume was compared between the treadmill training and the control groups for both the young and old rats at 1 or 2 weeks.

Results: After treadmill training for 1 week, the mean infarct volume was 7.26+/-0.49 and 9.51+/-0.84% for the young and old rats, respectively. The 1-week treadmill training effect was significant in the young rats (p=0.0207) but not in the old rats (p=0.0840). The mean infarct volume was 6.84+/-0.51 and 7.63+/-0.52% for the young and old rats, respectively, after the 2-week treadmill training. Both the young and old rat groups demonstrated a significant reduction in the infarct volume compared with that of the control group (p=0.021 for the young group and p=0.039 for the old group) after 2 weeks of treadmill training.

Conclusion: The present findings clearly demonstrate the different training effects of locomotor activity in reducing ischemic infarction in young and old rats. The delayed reduction in ischemic infarction in old rats was notable and may be attributable to the slow response of angiogenic and neurogenic mechanisms in the old rats.