In addition, Hou et al. investigated whether exogenous irisin (0.5 μg/g body weight) for 12 weeks ameliorated endothelial dysfunction in perivascular adipose tissue (PVAT) in obesity and showed that irisin enhanced ACh-induced vasorelaxation in the aorta both with and without PVAT [48]. Here, FNDC5 is linked to obesity due to melanocortin 4 receptor deficiency.