Since sympathetic nerve activity to the muscle vasculature and to the kidneys is elevated in obesity, metabolic syndrome, and diabetes (Grassi et al., 1998; Esler et al., 2006; Zhang et al., 2012; Coats and Cruickshank, 2014; Thorp and Schlaich, 2015), the results raised the interesting possibility that resistin may be a potential contributing factor to the cardiovascular complications associated with those metabolic conditions. This evidence concerns the gene RETN and obesity due to melanocortin 4 receptor deficiency.