Our results are supported by a previous study showing that central administration of ghrelin for 4 weeks increases anxiety- and depression-like behaviors in rats (Hansson et al., 2011), whereas are in conflict with another earlier study showing that ghrelin/GHS-R1a system plays antidepressant effects against CSDS (Lutter et al., 2008). The gene discussed is GHRL; the disease is major depressive disorder.