TPH2 and Anxiety: Moreover, Tph2−/− mice spent significantly less time in the center of the open-field compared to Tph2+/− and Tph2+/+ littermates (mean center time per visit: F(2,30)=4.47, P=0.020, Figure 5d; total center time: F(2,30)=2.97, P=0.067; Supplementary Figure S1), which together with increased escape behavior, points toward exaggerated anxiety-like behavior in the OFT.