¹Department of Psychiatry, Max Planck Institute of Psychiatry, Munich, Germany

Correspondence: Dr A Steiger, Department of Psychiatry, Max Planck Institute of Psychiatry, Kraepelinstrasse 10, Munich 80804, Germany. Tel: +49 89 30622 236; Fax: +49 89 30622 552; E-mail: steiger@mpipsykl.mpg.de

Received 6 July 2004; Revised 28 October 2004; Accepted 7 December 2004; Published online 26 January 2005.

Abstract

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 g 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, meanSEM 3516 ng/ml min after placebo [P] to 2808533 ng/ml min after ghrelin [G]; p<0.001), cortisol (5908984 ng/ml min [P] to 101791293 ng/ml min [G]; p<0.001), and ACTH (922103 pg/ml min [P] to 3030763 pg/ml min [G]; p<0.02), whereas leptin levels remained unchanged. Contrary to placebo, glucose concentration did not decrease markedly after administration of ghrelin. Our data suggest that i.v. ghrelin stimulates appetite and images of food in young women and men. Obviously, leptin is not involved in these effects.