In addition, leptin was shown to be responsible for the inhibition of the Neuropeptide Y (NPY) neurons, which is known to have a specific anxiolytic and neuroprotective properties (Reichmann and Holzer, 2016), and is proposed to play a critical role in mediating chronic stress in patients with depression (Widerlov et al., 1988; Jimenez Vasquez et al., 2000). This evidence concerns the gene LEP and major depressive disorder.