Somatostatin (sst) is a multifunctional peptide with two biologically active forms, sst-14 and sst-28, which are synthesized in neurons throughout the brain as well as in peripheral tissues such as the pancreas and the gut. SST exerts a diverse array of effects that include inhibition of endocrine secretion, modulation of neurotransmission, and regulation of cell proliferation by stimulating a family of five G-protein-coupled receptors. Somatostatin receptor sst2 mRNA is predominantly expressed in central nervous system. Study using sst2 knock-out mice has found the increased anxiety-related behaviour while locomotor and exploratory activity was decreased in stress-inducing situations (coupled with an increase in pituitary ACTH release, a regulator of the stress response). In the periphery, inhibition of glucagon release by sst in mouse islets is primarily mediated via sst2. In addition, endogenous sst functions through sst2 to suppress gastric acid secretion through inhibition of gastrin activity.