Ghrelin Stimulates Appetite, Imagination of Food, GH, ACTH, and Cortisol, but does not Affect Leptin in Normal Controls: Clinical Research

Ghrelin, a growth hormone (GH) secretagogue receptor ligand was isolated from the stomach and hypothalamus of rats and humans. In rodents, ghrelin exerts distinct orexigenic action, probably as counterpart of the anorexigenic leptin. In humans, ghrelin infusion enhances appetite. It is unknown whether single intravenous (i.v.) injections of ghrelin affect human eating behavior. Therefore, we investigated the influence of a single i.v. bolus injection of 100 μg ghrelin on appetite, ideas about food, hormone levels, and glucose concentration in young control subjects. In order to test gender differences, we included five women and four men. After ghrelin administration, appetite was enhanced in eight of nine subjects. Seven probands reported a vivid, plastic image of their preferred meal. Furthermore, ghrelin stimulated an immediate increase in plasma levels of GH (area under the curve, mean±SEM 35±16 ng/ml × min after placebo [P] to 2808±533 ng/ml × min after ghrelin [G]; p