Observations on the growth hormone, insulin, and glucagon release-inhibiting activities of somatostatin analogues

Somatostatin was isolated from extracts of ovine¹ and porcine² hypothalamic tissue and was found to be a cyclic tetradecapeptide with the following sequence: {A figure is presented} Subsequent studies revealed that the peptide not only had inhibiting effects on growth hormone (GH) release, but also on pituitary thyrotropin (TSH) and a large array of gastrointestinal and pancreatic hormones, including insulin, glucagon, gastrin and gastric acid, secretin, CCK, GIP, VIP, and motilin. These activities have been recently reviewed.³. The therapeutic value of somatostatin in several important areas is diminished by its broad spectrum of activities. As with most naturally occurring peptides, somatostatin also has a short biologic half-life, ⁴ making its long-term use impractical. Therefore, analogues are being designed for enhanced, prolonged, and selective activities. In addition, competitive inhibitors of somatostatin could be of great interest and pharmacologic value.