Although neuronal growth and restructuring have been reported as compensatory changes that occur after CNS insult, it is not clear if they correspond to functional improvement. Here we examined whether dendritic growth and cognitive improvement can be enhanced by rehabilitation training. Sixty-two adult male Wistar rats received either cerebral 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 8 days in the water maze for: place learning (4 days) and cue-guided learning (4 days) with 2 days of rest in between blocks of testing. Immunohistochemical results showed increased expression of microtubule-associated protein 2 (MAP2), a substrate believed to be associated with the formation of dendrites, in all ischemic rats and in sham animals housed in EC compared to the sham EX and sham control groups. Interestingly, animals housed in EC have significantly higher MAP2 expression overall. Behavioral analyses showed significantly shorter mean swim latencies in both the place and cue-guided learning tasks in animals assigned to EC compared to their EX and social control counterparts. Furthermore, MAP2 expression accounted for 26% and 22% of the variance in swim latency in the place and cue-guided learning task in EC rats, respectively. No significant differences were seen between the ischemia EC and sham EC rats in MAP2 expression and functional performance. These results suggest that rehabilitation training probably enhanced compensatory dendritic restructuring after injury. Moreover, enhancement of dendritic restructuring may have contributed to the improvement of function in the EC rats. Thus, it is possible that EC but not EX is more effective in enhancing dendritic plasticity and recovery of function after cerebral ischemia. (Funded by NIH NR05260)
Session #1213 - Cardiovascular Interventions and Outcomes
The 29th Annual MNRS Research Conference (April 1-4, 2005)