Ghrelin: update on a novel hormonal system.

Ghrelin is a peptide hormone secreted into the circulation from the stomach but also synthesised in a number of tissues, suggesting both endocrine and paracrine effects. These include: stimulation of GH, prolactin and ACTH secretion; an increase in appetite; a diabetogenic effect on carbohydrate metabolism; positive inotropic effects on heart; vasodilatation; and effects on cell proliferation. The possibility of chronic manipulation of the ghrelin system on body weight, growth and appetite remains an exciting new field of exploration.