Differential behavioral outcome of anxiety tests in runner rats treated with corticosterone

Both clinical and pre-clinical studies have suggested that physical exercise is beneficial for lowering anxiety. However, some animal studies fail to demonstrate the anxiolytic effect of physical exercise. The inconsistencies among studies may be due to differences in animal models and behavioral tests. Previously, injection of corticosterone (CORT) for 14 days induced depression-like behavior to varying based on was shown. Animal model was used to investigate whether CORT treatment induced anxiety-like behavior and to examine the anxiolytic effect of voluntary running using two behavioral measurements: open field test and elevated plus maze. Results indicated that running reduced anxiety-like behavior in vehicle-treated animals in both tests. Treatment with CORT showed a significant anxiogenic effect in the open field test regardless of the doses, but not in the elevated plus maze. Running reduced anxiety in theopen field test, but showed no effect in elevated plus maze in the CORT-treated rats. The data suggest the discrepancy of these two anxiety-related measures in the animal model of stress. Key words: Corticosterone (CORT), stress, voluntary running, open field test, elevated plus maze, anxiety-like behavior.