Postischemic exercise decreases neurogenesis in the adult rat dentate gyrus.

Running exercise enhances neurogenesis in the normal adult and aged hippocampus. However, the effect of exercise on neurogenesis in the ischemic hippocampus is unclear. Here, we show that running exercise has different effects on ischemic and non-ischemic brain. Young (3-4-month-old) normotensive Wistar rats were used for this study. We administered bromodeoxyuridine (BrdU) to rats 7 days after the induction of transient forebrain ischemia or sham operation. BrdU-labeled cells were increased in the ischemic subgranular zone (SGZ) and granule cell layer (GCL) and double immunofluoresence showed approximately 80% of BrdU-labeled cells expressed neuronal markers. To assess the effect of running exercise on neurogenesis, BrdU-labeled cells in these regions were quantified after 1 day and 14 days. In sham-operated rats, the numbers of BrdU-labeled cells were significantly increased (2.2-fold) in the SGZ and GCL in response to running exercise. The numbers of BrdU-labeled cells were increased in response to ischemia, however, they were decreased 14 days after BrdU administration and running exercise accelerated the reduction in BrdU-labeled cells in ischemic rats. These findings suggest that running exercise has a negative effect on neurogenesis in the ischemic hippocampus. This may be important with respect to assessment of therapeutic approaches for functional recovery after stroke.