title: High biological activity of the synthetic replicates of somatostatin-28 and somatostatin-25.
abstract: We have isolated form extracts of ovine hypothalami two molecules characterized as somatostatin-28 and somatostatin-4-28 (referred to as somatostatin-25). They were reproduced by solid hase synthesis. In equimolar ratio and depending upon the experimental conditions, synthetic somatostatin-28 ans somatostatin-25 are 3-14 times more potent than somatostatin-14 to inhibit the basal in vitro secretion of growth hormone or as stimulated by prostaglandin (PGE2). In early studies in vivo, somatostatin-28 and somatostatin-25 are also more potent than somatostatin-14 in inhibiting the secretion of growth hormone acutely stimulated in the rat by injection of morphine; somatostatin-28 is also longer-acting than somatostatin-14. These results suggest that somatostatin-14, as originally isolated, is a biologically active fragment of a larger molecule of greater specific activity; it should be considered as another form of somatostatin with high biological activity present in some tissues and likely secreted y the tissues along with somatostatin-14 and possibly other somatostatin-peptides of diverse sizes.
mesh_terms: D000818:Animals; D013006:Growth Hormone / Q000378:metabolism*; D007031:Hypothalamus / Q000032:analysis; D066298:In Vitro Techniques; D008297:Male; D009020:Morphine / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011458:Prostaglandins E / Q000494:pharmacology; D011498:Protein Precursors / Q000494:pharmacology; D051381:Rats; D012756:Sheep; D013004:Somatostatin / Q000494:pharmacology*; D053561:Somatostatin-28
chemical_list: D011458:Prostaglandins E; D011498:Protein Precursors; D013004:Somatostatin; C026568:somatostatin 25; D053561:Somatostatin-28; D009020:Morphine; D013006:Growth Hormone