Anxiety-like behaviour in the LDB and the EPM was similar between groups (Fig. 2I, J; LDB: t47 = 1.324; p = 0.192; n = 24–25/group; EPM: t47 = 1.324; p = 0.192; n = 24–25/group), suggesting that STAT3 knockout in serotonergic neurons does not influence anxiety-like behaviour in a situation of free choice. This evidence concerns the gene STAT3 and Anxiety.