Memory-enhancing effects of DHEAS in aged mice on a win-shift water escapetask

The steroid hormone, dehydroepiandrosterone (DHEA) and its sulfate DHEAS) h ave been implicated in age-associated deficits in memory. Numerous studies have demonstrated the effectiveness of these neurosteroids to enhance reten tion and meliorate the effects of various memory-blocking agents, but few s tudies have directly assayed their effects on memory in aged animals. The p resent study investigated the memory-enhancing effects of DHEAS in a win-sh ift (nonmatching-to-sample) task in aged mice using water escape motivation . Sixteen CD-1 mice, 18-20 months old, were trained to a moderate criterion of 7/10 correct trials and were then divided into two equal groups based o n acquisition performance. One group received oral administration of DHEAS (1.5 mg/mouse/day) in a vehicle solution (0.0015% methyl salicylate) while the other group received the vehicle alone. DHEAS effects were assessed usi ng a procedure in which delay intervals (0,20, and 240 s) were interposed b etween sample and comparison trials over the course of three test sessions. The group receiving DHEAS recorded significantly higher retention scores a cross 3 days of testing, particularly at the 120-s delay interval, indicati ng that DHEAS enhanced working memory in these aged animals. (C) 2001 Elsev ier Science Inc. All rights reserved.