Fig. 3.

Tyrosine hydroxylase (TH) immunoreactivity (ir) in the locus coeruleus (LC) neurons of mood disorder patients. TH-ir (blue) was present in the cytoplasm of neurons containing neuromelanin (dark brown), both in controls (A and C) and in patients with major depressive disorder (MDD, B) or bipolar disorder (BD, D). TH-ir was significantly higher in the MDD group than in its control group, while there was no significant difference in TH-ir between the BD and control groups (E). Note that the TH-ir levels in patients who committed suicide were in the range of those who did not have suicidal ideation or attempts. In addition, the TH-ir levels of those who died in summer (Jul-Aug) showed no significant differences from those who died in the other seasons (F). The data are shown as mean + SD. IOD, integrated optical density; CTR1, control group for BD; CTR2, control group for MDD; **P < 0.01; scale bar, 200 μm.