ABSTRACT
Major depression is a severe and debilitating emotional disorder predicted to become the second leading cause of disability worldwide (Murray and Lopez 1996). In addition, Kessler et al. (2003) observed up to 60% co-occurrence of major depression with anxiety in the U.S. National Comorbidity Survey. This complex emotional dysfunction is often characterized by anhedonia, hopelessness, exacerbated guilt, and memory de˜cits (Castaneda et al. 2008). Commonly prescribed antidepressants are not curative, and a considerable subpopulation of depressed subjects is resistant to these treatments (Berlim et al. 2008). In recent years, various neuropeptides have been proposed to play signi˜cant roles in the etiology of depression in addition to classical neurotransmitters (Alldredge 2010; Rotzinger et al. 2009). Among those peptides, neuropeptide Y (NPY) was shown to be dysregulated in depression and other emotional conditions and to have antidepressant properties (Dumont et al. 2009; Morales-Medina et al. 2010).
