STAT3 and obesity due to melanocortin 4 receptor deficiency: Interestingly, in a previous study of HFD mice, a common model of obesity characterized by high circulating leptin and leptin resistance, CNTF administration induced P-STAT3 immunoreactivity in ME cells, the ependyma and ARC neurons but also, to a lesser and variable extent, in some neurons located in the DMH, VMH, PF-LHA and the mammillary body (Severi et al., 2013).