Somatostatin Agonists and Antagonists - Peptide Control of Growth Hormone Secretion
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Although somatostatin itself has numerous inhibitory activities which individually are of no little therapeutic interest, there are also several types of physiological effects where it might be of even greater basic and medical value to block activity instead. Perhaps principal among these would be an ability to block the inhibitory effects of somatostatin on growth hormone (GH) release. Antibody experiments (1) have clearly shown that basal GH levels are elevated when somatostatin is neutralized. There is also an unwanted negative participation of somatostatin when GH levels are stimulated with the GH-releasing factor, GRF. In fact, one group has actually been able to demonstrate that GRF(1–44) stimulates somatostatin release from hypothalamic cells in culture (2). It should also be mentioned that both GH (3) and somatostatin (4) can alter somatostatin levels. Somatomedin C has also been implicated in the negative feedback regulation of GH, at least partially by stimulating release of somatostatin (5). Given the successes which have been achieved in the development of very potent competitive antagonists of other peptides, notably in our own experience with LH-RH, there appears to be no reason to neglect the development of a somatostatin antagonist any longer.
KeywordsGrowth Hormone Growth Hormone Level Growth Hormone Release Glucagon Release Plasma Growth Hormone Level
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