Possible Interaction: Somatostatin and Adrenocorticotropic Hormone

“ Somatostatin lowered ACTH levels in both patients, more effectively in the patient with non-invasive pituitary adenoma.”

“The mechanism by which somatostatin analogs suppress ACTH production by corticotropinomas has yet to be fully elucidated.”

“A hypothalamic corticotropin release inhibiting factor CRIF ) that inhibits ACTH synthesis and secretion has long been postulated but was not characterized until recently.”

“ Somatostatin and its analogs as octreotide decrease ACTH secretion through somatostatin receptors of pituitary cells.”

“ Somatostatin (SST), an inhibitory polypeptide with two biologically active forms SST14 and SST28, inhibits GH, prolactin (PRL), TSH, and ACTH secretion in the anterior pituitary gland.”

“In pathological conditions of a low endogenous cortisol level, i.e. in patients with adrenal insufficiency and in patients with Nelson’s syndrome, SS and sst2-preferring SS analogs (SSA), such as octreotide, are able to lower circulating ACTH and cortisol levels.”

“ Somatostatin (SS) inhibits pituitary adrenocorticotropin hormone (ACTH) secretion in vitro, but the sensitivity to SS is strongly regulated by glucocorticoids.”

“We tested SRIF-independent constitutive SST activity in AtT20 mouse pituitary corticotroph cells in which ACTH secretion is highly sensitive to SRIF action.”

“Both SS and CST decreased ACTH , although statistical difference was reached only during CST (P < 0.05).”

“These findings suggest that somatostatin is a potent inhibitor of ACTH secretion, however, only in a condition in which glucocorticoids are lacking.”

“These findings provide evidence that the stimulatory effect of ANG II on GH, but not ACTH secretion, is under the inhibitory control of somatostatin , suggesting an interaction between ANG II and SRIH in regulation of GH secretion.”