Central mineralocorticoid receptors are indispensable for corticosterone-induced impairment of memory retrieval in rats

Previous studies indicated that stress levels of glucocorticoid hormones (cortisol in humans, and corticosterone in rodents) induce impairment of long-term memory retrieval, but the underlying mechanisms (genomic or nongenomic) are not clear. To clarify this issue, we investigated the involvement of brain corticosteroid receptors and protein synthesis in the corticosterone-induced impairment of memory retrieval. Young rats were trained in the water maze task with six trials per day for 6 consecutive days. Retention of the spatial training was assessed 24 h after the last training session with a 60-s probe trial. Experiments included intraventricular injections of anisomycin, a specific protein synthesis inhibitor or specific antagonists for both types of corticocosteroid receptors (mineralocorticoid receptor, MR, and glucocorticoids receptor, GR) before corticosterone administration shortly before retention testing. The results showed that administration of anisomycin did not change the corticosterone response. Administration of the MR, but not GR, antagonist blocked the corticosterone-induced response dose dependently. These findings provide evidence for the view that glucocorticoids impair memory retrieval through nongenomic mechanisms involving an interaction with central MRs.