LEP and obesity due to melanocortin 4 receptor deficiency: Similarly, in 2016, Pereira and colleagues used modified, BBB-impermeable diphtheria toxin to genetically sympathectomies a TH-Cre; LSL-DTR mouse strain and found doing so inhibited reductions in body weight in response to a leptin challenge and predisposed subjects to obesity upon a high fat diet challenge (Pereira et al., 2017).