Ghrelin is a multifaceted gut hormone that activates its receptor, growth hormone secretagogue receptor (GHS-R). Ghrelin's hallmark functions are its stimulatory effects on growth hormone release, food intake and fat deposition. Ghrelin is famously known as the ‘hunger hormone’. However, ample recent literature indicates that the functions of ghrelin go well beyond its role as an orexigenic signal. Here, we have reviewed some of the most recent findings on ghrelin and its signalling in animals and humans.
Ghrelin regulates glucose homeostasis by inhibiting insulin secretion and regulating gluconeogenesis/glycogenolysis. Ghrelin signalling decreases thermogenesis to regulate energy expenditure. Ghrelin improves the survival prognosis of myocardial infarction by reducing sympathetic nerve activity. Ghrelin prevents muscle atrophy by inducing muscle differentiation and fusion. Ghrelin regulates bone formation and metabolism by modulating proliferation and differentiation of osteoblasts.
In addition to ghrelin's effects on appetite and adiposity, ghrelin signalling also plays crucial roles in glucose and energy homeostasis, cardioprotection, muscle atrophy and bone metabolism. These multifaceted roles of ghrelin make ghrelin and GHS-R highly attractive targets for drug development. Ghrelin mimetics may be used to treat heart diseases, muscular dystrophy/sarcopenia and osteoporosis; GHS-R antagonists may be used to treat obesity and insulin resistance.
aUSDA/ARS Children's Nutrition Research Center, Department of Pediatrics
bDivision of Diabetes, Endocrinology, and Metabolism, Department of Medicine
cHuffington Center on Aging, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
Correspondence to Yuxiang Sun, MD, PhD, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Ave. Room 5024, Houston, TX 77030, USA. Tel: +1 713 798 7167; fax: +1 713 798 9396; e-mail: firstname.lastname@example.org