UCP3 and obesity due to melanocortin 4 receptor deficiency: An even stronger decrease in cardiac UCP3 content was observed in the LoxTB MC4R−/− mice (28–34% decrease) and LepR/Nestin-cre mice (38–40% decrease; Fig. 1e, g), two other models of type 2 diabetes which are also characterized by severe obesity, insulin resistance, hyperinsulinemia, and glucose intolerance [7, 49].