In gastrointestinal functional disorders, where 5-HT is excessively released, such as disorders following cancer chemotherapy [13] and SSRI administration [19], 5-HT2B⁄2CR stimulation causes decreased peripheral and central ghrelin concentrations, and RKT restores decreased peripheral acylated ghrelin secretion to normal levels via antagonizing these receptors. This evidence concerns the gene GHRL and cancer.