Indeed, several HDAC inhibitors, including SB (Tsankova et al., 2006), Entinostat (MS-275; Covington et al., 2009), and suberoylanilide hydroxamic acid (SAHA; Covington et al., 2009), have demonstrated antidepressant qualities and upregulate BDNF, NGF and GDNF (Valvassori et al., 2014) as well as reduce Hdac5 expression in the hippocampus, reversing depression like phenotypes in models of chronic social defeat (Schroeder et al., 2007; Covington et al., 2015). This evidence concerns the gene HDAC9 and major depressive disorder.