Synthesis and secretion of growth hormone by the anterior pituitary gland is mainly controlled by two antagonist hypothalamic neuropeptides: the stimulatory hormone GHRH and the inhibitory hormone somatostatin. The GHRH receptor (GHRH-R) is a member of the seven-transmembrane G-proteincoupled receptor superfamily. It interacts with Gs protein to stimulate adenylate cyclase activity and cyclic AMP (cAMP) production. Both GHRH and cAMP are known to be involved in somatotroph proliferation and differentiation. Growth hormone-releasing hormone was purified for the first time in 1982 from a pancreatic tumor responsible for acromegaly and pituitary hyperplasia. In transgenic mice, overexpression of GHRH causes also gigantism and somatotroph hyperplasia or tumor.
Growth hormone (GH) deficiency leading to growth failure might result from alterations of the hypothalamic control of the anterior pituitary, abnormal development of the somatotroph cell or GH synthesis and alterations of secretion. Some familial cases of GH deficiency have been explained by mutations of