BDNF and obesity due to melanocortin 4 receptor deficiency: To date, a number of studies have shown that myokines, such as interleukin-6 (IL-6), interleukin-15 (IL-15) and brain-derived neurotrophic factor(BDNF), may be potential regulators of many physiological states and metabolic diseases, such as obesity and IR [5–8].