Experience‐dependent Facilitating Effect of Corticosterone on Spatial Memory Formation in the Water Maze

Abstract

Stress‐related adrenal steroid hormones modulate brain and cognitive function. Electrophysiological studies, including primed burst potentiation and long‐term potentiation, have indicated concentration‐dependent inverted U‐shape effects of corticosterone in hippocampal function and plasticity. Here, we explored the role of corticosterone in the consolidation and long‐term retrieval of spatial learning in the Morris water maze task in rats. We postulated that corticosterone actions might be experience‐dependent with regard to stimulus intensity, such as differential water temperatures. Indeed, rats trained at 19°C showed a quicker rate of acquisition and better long‐term retention than rats trained at 25°C water. In addition, post‐training corticosterone levels, on the first training day, were significantly higher in rats in the 19°C group than in the 25°C group. Performance of rats trained at 25°C, but not at 19°C, water was improved by injecting them i.p. with corticosterone immediately after each training session. Thus, the effect of exogenously administered corticosterone appears to be experience‐dependent, with the experience‐induced corticosterone concentrations as a critical factor determining the cognitive consequences of steroid treatment. Therefore, this work indicates a facilitating corticosterone action, during the post‐training period, on the neural mechanisms determining the strength of information storage under acute, physiological conditions.

Stress facilitates consolidation of verbal memory for a film but does not affect retrieval.

“…Of the human studies that have administered a stress induction or cortisol prior to consolidation and tested recall at least 24 hr later (when cortisol levels have returned to baseline), three have found a facilitative effect on consolidation of visual memory (picture recall) for affective (Buchanan & Lovallo, 2001;Cahill et al, 2003) and neutral (Abercrombie et al, 2003) information. This is consistent with animal studies using spatial memory paradigms, such as mazes (Conrad, Lupien, Thanasoulis, & McEwen, 1997;Sandi et al, 1997). That we did not obtain similar findings for visual information on the film measure is surprising (we discuss this below).…”

Hippocampal gene expression induced by cold swim stress depends on sex and handling

“…Sgk1 has also been proposed to play a critical role in memory performance, as fast learning rats have higher levels of Sgk1 mRNA than slow learners, and Sgk1 inhibition impairs, while Sgk1 overexpression enhances memory consolidation (Lee et al, 2007). The rapid activation of Sgk1 in response to acute stress could thus be important for the effects of stress on memory performance, as it is well-known that acute stress can enhance memory acquisition (Sandi et al, 1997). Our data confirm a previous report that acute swim stress induces Sgk1 expression in the hippocampus (Gray et al, 2013).…”

Hippocampal neuroplasticity induced by early-life stress: Functional and molecular aspects

“…Whereas acute mild stress rapidly enhances synaptic efficacy and learning and memory processes [131,45,91,123], chronic or severe activation of the stress response early in life has been shown to be potentially injurious in both humans [6,120,147] and experimental animals [120,31]. For example, severe childhood psychological stress (neglect and abuse) correlates with a higher incidence of learning disabilities later in life, including those learning and memory functions requiring an intact hippocampus [121,50].…”