The effect of mild post-stroke exercise on reactive neurogenesis and recovery of somatosensation in aged rats.

Exercise impacts the cellular response and behavioral recovery following stroke, but has not been widely investigated in aged animals. We tested the hypothesis that gentle post-stroke exercise could enhance recovery of somatosensory function and influence survival and phenotype of newly generated cells in the peri-infarct region after focal cortical ischemia in aged rats. Focal stroke was induced in the forelimb area of the sensorimotor cortex in 18-month old male rats using the vasoconstrictor endothelin-1. Beginning 1 week after stroke or sham surgery, half of the animals walked 100-300 m daily, 5 days per week. Bromodeoxyuridine (BrdU) was administered on days 6-8 post-stroke in order to label proliferating cells, the survival and phenotype of which were examined 4 weeks later using confocal microscopy. Post-stroke exercise enhanced recovery of somatosensory function as measured by the Adhesive Removal Test. Stroke, but not exercise, increased the number of BrdU+ cells in the peri-infarct region. In aged rats, mild post-stroke exercise enhances recovery of somatosensation, but has little effect on survival and phenotype of cells born in response to ischemia. Our results underscore the need for further study of clinically relevant post-stroke exercise regimens.