Ghrelin: A gut hormonal basis of motility regulation and functional dyspepsia

Functional dyspepsia (FD) is a functional gastrointestinal disorder (FGID). Several pathophysiological mechanisms have been indicated as possible etiological factors, such as delayed gastric emptying, impaired proximal gastric accommodation and visceral hypersensitivity. Ghrelin is an important gut hormone. It is a motilin-related peptide that was discovered in the stomach, and it acts as an endogenous ligand of growth hormone secretagogue receptor. Ghrelin plays an important role in the stimulation of food intake and gut motility. Acyl ghrelin stimulates the percentage motor index (%MI) in the antrum and induces fasted motor activity in the duodenum. Des-acyl ghrelin decreases food intake and decrease gastric emptying. Although some studies have demonstrated that plasma acyl ghrelin levels tend to be lower in FD patients than in controls, the association between plasma ghrelin levels and FD remains controversial. Previous reports have demonstrated that hunger sensation was elevated through the administration of ghrelin to patients with FD. However, there have been few clinical reports relating to the administration of ghrelin. Altered gut-brain interactions may underlie the symptoms of FD. Ghrelin may be associated with FD through its effect on the regulation of gut motility. Further studies are needed to examine the effects of ghrelin in FD.