Stress and glucocorticoids impair inhibitory avoidance memory retrieval and extinction in male mice: the ameliorative effect of Ginkgo biloba extract.

Abstract

Memory retrieval involves recalling previously consolidated information, while memory extinction refers to the gradual weakening of such memories after recall. Stress and glucocorticoids influence the retrieval and extinction of memory. This study employed a passive avoidance task to examine the impact of acute mild stress and equivalent doses of exogenous corticosterone on fear memory retrieval and extinction in male mice. Subsequently, we investigated the potential therapeutic effects of Ginkgo biloba extract, EGb 761, on memory impairments induced by stress and corticosterone. Corticosterone was administered systemically 30 min before memory reactivation to model glucocorticoid activity during retrieval. Mild acute stress, like the stress levels typically experienced before an exam, was induced through 20-min restraint immediately before reactivation in separate groups. EGb 761 was injected 30 min before corticosterone or stress exposure. Results demonstrated that both corticosterone and acute stress impaired context-specific fear memory retrieval and enhanced subsequent extinction. Pretreatment with EGb 761 inhibited these impairing effects of acute stress and corticosterone on avoidance memory retrieval and extinction. Our findings suggest that the glucocorticoid system and acute stress markedly influence avoidance memory retrieval and extinction. Ginkgo biloba may possess therapeutic and memory-enhancing effects, particularly in stressful situations.