IDO1 and Alzheimer disease: Figure 4 demonstrates significantly higher levels of TDO but not IDO1 protein were detected in the cerebellum of 8-month-old 3xTg AD, compared to those in same age WT mice (p<0.01). Moderate but not significant increased levels of TDO and IDO1 proteins were also appeared in the hippocampus of same age of 3xTg AD brains (Fig. 4, lower panel). TDO stained almost all neurons (NeuN) and microglia (BS-Isolectin-B4), but its staining was observed in only some astrocytes (GFAP). The staining of TDO in neurons, microglia and astrocytes was cytoplasmic (Fig. 5).