A cyclic peptide hormone; SST receptor agonist (IC50s = 0.22, 0.10, 0.28, 1.23, and 0.30 nM, respectively, in CCL39 cells expressing human recombinant SST1-5); inhibits forskolin-induced cAMP accumulation in CCL39 cells expressing human recombinant SST1-5 (EC50s = 6.16, 4.37, 17.38, 2.95, and 4.67 nM, respectively); inhibits the release of growth hormone, prolactin, thyrotropin, glucagon, and insulin, as well as other signaling molecules