Clinical application of ghrelin in the field of surgery

Ghrelin was discovered as an intrinsic ligand for the growth hormone (GH)-secretagogue receptor (GHS-R) in 1999. The endogenous production of ghrelin occurs mainly in the stomach. Ghrelin has multiple functions; it has orexigenic action, stimulates GH secretion, has anti-inflammatory activities, stimulates gastrointestinal activity, stabilizes heart function and has other metabolic roles. Moreover, ghrelin is the only gastrointestinal hormone known to stimulate appetite. In the past decade, clinical applications of ghrelin have been attempted for various pathologies, based on its anabolic function, including applications for patients with anorexia nervosa and cachexia due to chronic heart, renal or pulmonary diseases. In the field of surgery, we have conducted several clinical trials using exogenous ghrelin in patients undergoing total gastrectomy, esophagectomy and neoadjuvant chemotherapy, including cisplatin treatment, and consistently obtained unique and striking benefits in these patients. Ghrelin comprehensively improves the patients' general conditions and quality of life via its pleiotropic physiological functions. This characteristic is unique and different from the existing drugs; therefore, ghrelin may be an indispensable supplement to prevent surgical stress and postoperative sequelae. This review summarizes the recent advances toward the clinical application of ghrelin.