STAT3 and obesity due to melanocortin 4 receptor deficiency: Hyperphagia, obesity and defective locomotion were observed in mice with deficiency of LepR or its key signaling molecule STAT3 in the LH or VTA on chow diet (Hommel et al., 2006; Leinninger et al., 2009; Leinninger et al., 2011; Fernandes et al., 2015).