MC4R and obesity disorder: Consequently, MC4R agonists have been developed as potential therapeutics for obesity (Kievit et al., 2013; Chen et al., 2015; Kuhnen et al., 2016) and have been proven effective in treatment of male and female sexual dysfunctions, whereas MC4R antagonists are potential anxiolytics that may function as antidepressants or for treating cancer-induced anorexia (Chaki et al., 2003; Ercil et al., 2005; Pontillo et al., 2005; Chaki and Okubo, 2007; Lansdell et al., 2010).