Serotonin (5-hydroxytryptamine, 5-HT) transporter (SERT) could be a critical link between depression and obesity, as it is well known that SERT is the major therapeutic target of a large class of antidepressant drugs, and also plays a vital role in the regulation of body fat stores and glucose homeostasis7. This evidence concerns the gene SLC6A4 and obesity due to melanocortin 4 receptor deficiency.