Effects of glucocorticoids on the regulation of the hypothalamic-pituitary-somatotropic system in depression

In order to evaluate the possible effect of glucocorticoids as neuromodulators of the hypothalamic-pituitary-somatotropic system in depression, cortisol, growth hormone (GH), and insulin-like growth factor I (IGF-I) concentrations were studied before and after oral administration of 1 mg dexamethasone at 11 p.m. in 16 patients during depression and after recovery and in 28 healthy controls. While there were no significant differences in GH and IGF-I levels between depressed, recovered and control subjects, GH and IGF-I concentrations of cortisol non-suppressors were significantly elevated compared to suppressors. Moreover, post-dexamethasone cortisol, GH, and IGF-I levels were positively correlated. Dexamethasone had a stimulating effect on GH and IGF-I values in patients during depression and in cortisol non-suppressors only; this effect was absent in recovered and in control subjects and in cortisol suppressors. Thus, hypercortisolemia may be of great importance for the dysregulation of the hypothalamic-pituitary-somatotropic system reported in depression.