TNF and Anxiety: Yamada et al. (2000) showed that TNF-α knockout mice display a mild antidepressant phenotype. Along these same lines, administration of the TNF-α inhibitor infliximab during chronic mild stress significantly decreased immobility time in the forced swim test, increased sucrose consumption during the sucrose preference test, and decreased anxiety-like behavior in the elevated plus maze (Karson et al., 2013).