NPY and major depressive disorder: There are a number of data indicating that NPY and its receptor ligands produced antidepressant-like effects in animal models of depression (Stogner and Holmes 2000; Redrobe et al. 2002; Ishida et al. 2007; Walker et al. 2009; Packiarajan et al. 2011; Morales-Medina et al. 2012b; Desai et al. 2014).