EDN1 and obesity due to melanocortin 4 receptor deficiency: Insulin resistance, as observed in metabolic syndrome, type 2 diabetes, arterial hypertension, and obesity, determines important alterations in circulatory homeostasis, such as via the synthesis of endothelin-1 (ET-1) over that of nitric oxide (NO), stimulating the sympathetic system and acting as a growth factor for the cells of the vascular wall [15], i.e., activating a whole series of factors that produce and worsen atherosclerosis.