Physiological Functions and Pathology of Ghrelin

Ghrelin is a peptide hormone made up of 28 amino acid residues; the N-terminal serine 3 residues is modified by octanoic acid, a medium-chain fatty acid. Ghrelin is mainly secreted by the stomach and has various effects, including growth hormone release, hyperphagia, lipid accumulation, suppression of insulin secretion, and hypotensive effects. Most of these physiological effects are indispensable functions for the maintenance of homeostasis and contribute to the onset and promotion of metabolic syndrome. Accordingly, it is important to combine etiological and pathological understanding based on the biochemistry and physiology of ghrelin, which has a characteristic structure. In this manuscript, after presenting biochemical information on ghrelin, we provide an outline of its physiological function.