STRESS AND GLUCOCORTICOIDS IMPAIR RETRIEVAL OF LONG-TERM SPATIAL MEMORY

Extensive evidence from animal and human studies indicates that stress and glucocorticoids influence cognitive function(1-11). Previous stud ies have focused exclusively on glucocorticoid effects on acquisition and long-term storage of newly acquired information. Here we report th at stress and glucocorticoids also affect memory retrieval. We show th at rats have impaired performance in a water-maze spatial task after b eing given footshock 30 min before retention testing but are not impai red when footshock is given 2 min or 4 h before testing. These time-de pendent effects on retention performance correspond to the circulating corticosterone levels at the time of testing, which suggests that the retention impairment is directly related to increased adrenocortical function. In support of this idea, we find that suppression of cortico sterone synthesis with metyrapone blocks the stress-induced retention impairment. In addition, systemic corticosterone administered to non-s tressed rats 30 min before retention testing induces dose-dependent re tention impairment. The impairing effects of stress and glucocorticoid s on retention are not due to disruption of spatial navigation per se. Our results indicate that besides the well described effects of stres s and glucocorticoids on acquisition and consolidation processes, gluc ocorticoids also affect memory retrieval mechanisms.