AGT and obesity due to melanocortin 4 receptor deficiency: Obesity resistance phenotype has been generated upon deletion of many receptors in these systems (Yvan-Charvet et al., 2005; Mori et al., 2008) as well as of the AngII precursor molecule angiotensinogen (Massiera et al., 2001), which corroborates the physiological relevance of these systems in the regulation of metabolic activity and body mass maintenance.