Changes in astrocyte production and cognitive impairment have been well-documented consequences of CNS injury. Here we examined whether astrocytic changes after cerebral ischemia can be influenced by rehabilitation training and if these changes were associated with cognitive improvement. Sixty-four adult male Wistar rats received either ischemia or sham surgery. Within 3 days after surgery, animals in each group were randomly assigned to either: complex environment housing (EC), treadmill exercise (EX), or socially paired housing (controls). After 14 days of behavioral training, rats were tested for 12 days in the water maze for: place learning (4 days)and non-spatial learning (4 days) tasks with 2 days of rest in between blocks of testing. Immunohistochemical results showed increased expression of reactive astrocytes in all ischemic rats and in sham animals housed in EC compared to the sham EX and control groups. When basic fibroblast growth factor (growth factor commonly expressed in astrocytes) was examined, results showed that the pattern of expression was similar to that of reactive astrocytes. Behavioral analyses showed significantly shorter mean swim latencies in the spatial learning tasks in animals assigned to the EC and EX groups compared to their SC counterparts. However, significantly shorter mean swim latencies in the non-spatial learning tasks were seen only in the ischemia EC and sham EC groups compared to their EX and SC counterparts. Additionally, a significant correlation was seen between increased astrocyte expression and cognitive improvement. These results suggest that behavioral training probably influenced the positive effects of ischemia-induced activation of astrocytes and that the benefits of these astrocytic changes may have been mediated by growth factor actions. Furthermore, it is possible that EC housing was more effective in enhancing the recovery of complex cognitive task. (Funded by NIH NR05260)
Session #1192 - Acute Care
The 29th Annual MNRS Research Conference (April 1-4, 2005)