Is there a role of ghrelin in preventing catabolism?

Catabolism is a metabolic process in which muscle and fat cell tissues are broken down in their constituent parts to provide nutrients and energy for the body. Whilst undoubtedly a potent stimulator of GH secretion in pharmacological doses, at present no clear physiological role for ghrelin in the regulation of GH secretion has been identified in man. In addition to its GH-releasing properties, ghrelin stimulates food intake and adipogenesis. The role of ghrelin has been extensively studied in three human models of catabolism: anorexia nervosa, cardiac cachexia and cancer cachexia. In this review we discuss the role of ghrelin in the etiology and treatment of catabolism using these three human models of catabolism. In the presence of clear catabolism in all the three conditions plasma total ghrelin levels are increased, suggesting that ghrelin does not increase food intake and/or anabolism in these circumstances. In addition, it is at present unknown whether administration of additional ghrelin in these conditions may reduce (or attenuate) the development of cachexia. In conclusion, the anabolic effects of ghrelin in man have still to be demonstrated.