Interestingly, in heterozygous BDNF+/- mice or in inducible BDNF KO lines of mice, deletion of BDNF in adults does not impact on depression-like behavior evaluated in the forced swim test (FST) (MacQueen et al., 2001; Saarelainen et al., 2003; Monteggia et al., 2007). This evidence concerns the gene BDNF and depressive disorder.