LEP and obesity due to melanocortin 4 receptor deficiency: A research by Natelson et al. found that obesity induced by deficiency of leptin receptor contributed to pathological changes and immature phenotype of the spinal disc.39 Besides, type II diabetes mellitus caused by leptin receptor knock out facilitated the disc cell apoptosis and ECM catabolism to promote IDD.40 Therefore, the roles of leptin signaling in IDD is complex and needs to be explored from multiple perspectives.