The 5-hydroxytryptamine (Htr) receptor is known to be involved in many important biological functions, including appetite, homeostasis, and gastrointestinal functions (Gershon, 2013); inflammatory responses (Mauler et al., 2016); regulation of lipid metabolism, together with peroxisome proliferator-activated receptors (PPAR) (Waku et al., 2010; Khademi et al., 2019); or the regulation of body weight or obesity (Crane et al., 2015; Oh et al., 2015; Wyler et al., 2017). Here, PPARA is linked to obesity due to melanocortin 4 receptor deficiency.