NPY and obesity due to melanocortin 4 receptor deficiency: NPY, which is mainly linked to the regulation of hunger and obesity, has recently been shown to contribute to osteoporosis- and osteoarthritis-related pain generation and perception in postmenopausal women (Xiao et al. 2016), patients with knee osteoarthritis (Wang et al. 2014) and in rat models of this disease (Adaes et al. 2015).