Targeting the ghrelin receptor to regulate food intake.

The increasing prevalence of obesity and the obesity-associated morbidities represent one of the major health problems of the western society. This has renewed interest in our understanding of factors that control appetite. The 28 amino acid peptide may represent one of the key players in the regulation of food intake since it is the only circulating orexigenic peptide. Ghrelin not only acts as a hunger signal but also as an adiposity signal. These effects are influenced by the internal energy status and can be considered as homeostatic signals. In addition ghrelin has direct effects on components of the reward system and increases the appetitive value of food. This hedonic feeding behavior of ghrelin can be considered as a non-homeostatic signal as it occurs in the absence of nutritional or caloric deficiency. In this review we address how these signals, elicited by ghrelin, can powerfully augment the drive to eat. Better understanding of the mechanisms by which ghrelin exerts its effect may enable the development of new treatments for obesity but also for conditions of cachexia.