BDNF and major depressive disorder: Quite unexpectedly, we found no notable change in accumbal BDNF levels in naive female depressive-like H mice, indicating that the increase in accumbal BDNF signaling observed in stress-induced models of depression (Weiss et al., 2001; Krishnan et al., 2007; Bessa et al., 2013) should not automatically be extended to genetic animal models of depression.