title: Somatostatin and dopamine receptor regulation of pituitary somatotroph adenomas.
abstract: Somatostatin and dopamine receptors are expressed in normal and tumoral somatotroph cells. Upon receptor stimulation, somatostatin and the somatostatin receptor ligands octreotide, lanreotide, and pasireotide, and to a lesser extent, dopamine and the dopamine analogs bromocriptine and cabergoline, suppress growth hormone (GH) secretion from a GH-secreting pituitary somatotroph adenoma. Somatostatin and dopamine receptors are Gαi-protein coupled that inhibit adenylate cyclase activity and cAMP production and reduce intracellular calcium concentration and calcium flux oscillations. Although their main action on somatotroph cells is acute inhibition of GH secretion, they also may inhibit GH production and possibly somatotroph proliferation. These receptors have been reported to create complexes that exhibit functions distinct from that of receptor monomers. Somatostatin suppression of GH is mediated mainly by somatostatin receptor subtype 2 and to a lesser extent by SST5. Human somatostatin receptor subtype 5 has also been shown to harbor mutations associated with GH levels, somatotroph tumor behavior, and somatostatin receptor ligand (SRL) responsiveness. Reviewing current knowledge of somatostatin and dopamine receptor expression and signaling in normal and tumoral somatotroph cells offers insights into mechanisms underlying SRL and dopamine agonist effectiveness in patients with acromegaly.
authors.affiliation: Pituitary Center, Division of Endocrinology, Diabetes and Metabolism, Cedars-Sinai Medical Center, Davis Building, Room 3021, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA. benshlomoa@cshs.org.
authors.forename: Anat
authors.initials: A
authors.lastname: Ben-Shlomo
authors.affiliation: Pituitary Center, Division of Endocrinology, Diabetes and Metabolism, Cedars-Sinai Medical Center, Davis Building, Room 3021, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA.
authors.forename: Ning-Ai
authors.initials: NA
authors.lastname: Liu
authors.affiliation: Pituitary Center, Division of Endocrinology, Diabetes and Metabolism, Cedars-Sinai Medical Center, Davis Building, Room 3021, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA.
authors.forename: Shlomo
authors.initials: S
authors.lastname: Melmed
mesh_terms: D000172:Acromegaly / Q000378:metabolism / Q000473:pathology; D000818:Animals; D006801:Humans; D010911:Pituitary Neoplasms / Q000378:metabolism* / Q000473:pathology*; D011954:Receptors, Dopamine / Q000378:metabolism*; D013004:Somatostatin / Q000378:metabolism*; D052683:Somatotrophs / Q000378:metabolism / Q000473:pathology
chemical_list: D011954:Receptors, Dopamine; D013004:Somatostatin
keywords: Acromegaly; Dopamine; Receptor; Somatostatin; Somatotroph