Role of Ghrelin
Ghrelin is a 28-amino-acid appetite-stimulating peptide hormone secreted by the stomach P/D1-type cells in mammals.
Des-octanoyl (or Des-acyl) Ghrelin is the unacylated precursor peptide to Ghrelin. Des-octanoyl Ghrelin is converted to Ghrelin by the enzymic addition of an octanyl group. Studies indicate that the amount of Des-octanoyl Ghrelin in the circulation is approximately 20-fold higher than that of Ghrelin. Des-octanoyl Ghrelin is not an agonist of the Ghrelin growth hormone receptor 1a (or growth hormone secretagogue receptor 1a; GHSR1a).
The active form of Ghrelin is a peptide with an n-octanoyl modification at Ser3 (n-octanoyl Ghrelin or acyl-Ghrelin). It is the endogenous ligand specific for GHSR1a which appears to be dedicated to Ghrelin and is widely expressed in different tissues.
Endogenous Ghrelin participates in the regulation of food intake and body weight. The secretion of ghrelin is augmented under conditions of both gastric emptying and filling, and the release is stimulated by intestinal hormones.
Ghrelin is also involved in the release of growth hormone from the anterior pituitary through activation of GHS-R1a.
It is also a potent vasodilator that can be detected in endothelial cells of arteries and veins in human.
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