Chronic corticosterone impairs memory performance in the Barnes maze.

Chronic stress has been reported to impair spatial memory and cause hippocampal impairment in rodents. Glucocorticoids are believed to be the active agent in this impairment. Studies have demonstrated that chronic glucocorticoid administration results in animals being impaired in the Morris water maze (MWM) or eight-arm radial maze. Although both of these methods are well established means of testing spatial memory, neither might be considered optimal for studying the behavioral effects of stress. The Morris maze is itself highly stressful to the animals. The eight-arm maze relies on a food reward to motivate the animals, and glucocorticoids have profound effects on hunger and satiety. We therefore investigated behavioral deficits of corticosterone-treated animals in the two previously used mazes and the Barnes circular platform maze (BCM), a test similar in design to the Morris maze, but one that does not require the animal to perform a highly stressful swim. Consistent with results in other tests, we found that animals that had been treated for 3 months with stress-equivalent concentrations of glucocorticoids showed significantly impaired behavior in the Barnes maze.