High biological activity of the synthetic replicates of somatostatin-28 and somatostatin-25

Regul Pept. 1981 Jan;1(4):255-64. doi: 10.1016/0167-0115(81)90048-3.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Growth Hormone / metabolism*
  • Hypothalamus / analysis
  • In Vitro Techniques
  • Male
  • Morphine / pharmacology
  • Pituitary Gland, Anterior / drug effects
  • Pituitary Gland, Anterior / metabolism*
  • Prostaglandins E / pharmacology
  • Protein Precursors / pharmacology
  • Rats
  • Sheep
  • Somatostatin / pharmacology*
  • Somatostatin-28


  • Prostaglandins E
  • Protein Precursors
  • Somatostatin
  • somatostatin 25
  • Somatostatin-28
  • Morphine
  • Growth Hormone