LEP and obesity due to melanocortin 4 receptor deficiency: The significance of our current work is that it highlights the potential for a much greater sympatho-excitatory effect on RSNA in conditions in which leptin and insulin are elevated, such as metabolic syndrome and obesity (Haynes et al., 1997 p. 2983; Paracchini et al., 2005; Schwartz and Porte, 2005; Prior et al., 2010).