We cannot rule out that pretreatment with a 5-HT2A agonist might temporarily reduce the downstream signal of a 5-HT2A pathway; thus, the particular timing employed here has a potential to work as an antagonizing treatment to the 5-HT2A signaling pathway. Because the pretreatment might reduce the amount of functional 5-HT2A receptors at the downstream signaling, liraglutide might not be able to induce a full anorexic effect. In addition, the similar effects of 5-HT2A receptor agonist and antagonist on food intake [14–16] might be due to the paradoxical phenomenon that both agonism and antagonism of 5-HT2A receptors induce 5-HT2A receptor's desensitization or downregulation .