Figure 1.

Summary of the mechanism of action of rikkunshito as a ghrelin enhancer. Ghrelin is produced from X/A-like cells near the gastric mucosa, and the ghrelin receptors at the ends of the vagus nerve in the surrounding tissues are stimulated. Most of it migrates to blood vessels and is carried to the brain. Serotonin, adrenaline, and CRF negatively regulate ghrelin secretion in the periphery. Rikkunshito suppresses the decrease in ghrelin that occurs in diseases by antagonistically acting on these factors with receptors in the periphery or central nervous system. Furthermore, rikkunshito enhances the binding of ghrelin to the ghrelin receptor and also acts on the ghrelin signal transduction system itself to enhance the ghrelin signal.