Excessive circulating levels of glucocorticoids are thought to be associated with cognitive impairment. We provide evidence that chronic activation of the glucocorticoid receptor (GR) in clonal neurons inhibits the transcriptional activity of the cyclic AMP response element-binding protein (CREB), which is believed to be involved in memory processes. To investigate the underlying mechanism we studied the phosphorylation of CREB and found altered phosphorylation kinetics in neurons chronically treated with glucocorticoids. Our results demonstrate a hitherto unrecognized crosstalk between the cyclic AMP and glucocorticoid pathway and may provide the molecular basis for the effects of long-term glucocorticoid exposure on cognitive function. (C) 2003 Elsevier Science (USA). All rights reserved.