BDNF and depressive disorder: The other animal model of depression, WKY rats, exhibits depressive-like behavior in the FST (Pare 1994; Armario et al. 1995; Lahmame and Armario 1996; Rittenhouse et al. 2002) and open field test (Pare 1994; Berton et al. 1997), together with abnormalities in some central neurochemical-dopaminergic (Jiao et al. 2006) and noradrenergic (Pardon et al. 2002) systems and hormonal dysregulation of the HPA (Solberg et al. 2001), as well as lower levels of brain-derived neurotrophic factor (BDNF) in the CA3 region of the hippocampus (Malkesman and Weller 2009).