GROWTH-HORMONE SECRETION - THE ROLE OF GLUCOCORTICOIDS

Glucocorticoids (GCs) modulate the somatotropic axis at a genomic and a non-genomic level. Critical concentrations of steroids not only dete rmine somatotrope differentiation but also enhance growth hormone (GH) gene expression. At a cellular level GH-releasing hormone (GHRH) and somatostatin (SS) are the two principal neuropeptides involved in the release of GH. In vitro data indicates that steroids enhance GH releas e by altering the affinity and the density of GHRH receptors. In addit ion, they reduce the sensitivity of the somatotrope to SS and decrease IGF-1 induced negative feedback on GH secretion. The net effect is an enhancement of GH release.