Box 7.16Ghrelin - birth of a hormone

  • The small synthetic hexapeptide hexarelin (GH releasing peptide-6, GHRP-6) was shown in the 1980s to cause the release of GH from somatotroph cells of a number of species.
  • Its mechanism of action was shown to be different from that of GHRH.
  • The production of analogs led to the cloning of the receptor mediating the actions on somatotroph cells, a highly conserved 366 amino acid protein.
  • The search for the endogenous ligand for the receptor proved difficult and was only solved by cloning the receptor into chinese hamster ovary (CHO) cells and testing extracts of a number of tissues for activity. The highest concentration of the putative ligand was found in stomach not hypothalamic extracts.
  • Studies are now required to establish its possible role in the control of GH secretion and its role in other tissues.
  • Interestingly, the ghrelin gene knock-out mouse grows normally.

From: Chapter 7, The pituitary gland

Cover of Endocrinology
Endocrinology: An Integrated Approach.
Nussey S, Whitehead S.
Copyright © 2001, BIOS Scientific Publishers Limited.

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