TET2 and major depressive disorder: Compared with the AR group, the data of the four groups of mice in the Tet2−/− AR group were also significantly different, reflecting the further aggravation of depressive symptoms, indicating that TET2 is involved in the depression-like behavior of AR mice, and the absence of TET2 will lead to the aggravation of depression-like behavior of AR mice (Fig. 2L, M).