STIMULATION BY UROCORTIN OF GROWTH-HORMONE (GH) SECRETION IN GH-PRODUCING HUMAN PITUITARY-ADENOMA CELLS

Urocortin (Ucn) possesses high homology with CRH and is considered to be a ligand to type-2 CRH receptor. We investigated the effect of Ucn on hormone release from cultured GH-producing human pituitary adenoma cells in vitro. GH-producing human pituitary adenoma cells were superf used on a Sephadex G-25 column. Both Ucn (10 nM) and CRH (10 nM) elici ted an increase in GH release from the pituitary adenoma cells in one patient with acromegaly. In contrast, GH release from the pituitary ad enoma cells was stimulated by Ucn but not by CRH in the other patient with acromegaly. These preliminary findings suggest that type-2 CRH re ceptors are expressed in some population of GH-producing human pituita ry adenoma cells and that Ucn might be involved in GH secretion from t umorous tissues in patients with acromegaly.