Bottomed out: metabolic significance of the circadian trough in glucocorticoid concentrations.

Mild chronic stressors characteristically increase circadian trough corticosteroid concentrations in rats and man. The elevation in trough concentrations is often accompanied by a reduction in peak concentrations and no change in the daily mean values. Here we point out that elevation of trough glucocorticoids, probably through daily increases of glucocorticoid receptor occupancy, has major metabolic effects that bias organisms toward storage of calories as fat. Thus, chronic mild stress, by overriding the normal mineralocorticoid receptor-mediated corticosteroid feedback regulation of trough CRF and ACTH secretion, facilitates development of the metabolic syndrome.