Distribution of HT7-positive human tau protein and its co-localization with RAGE in aged 3xTg-AD mice. Confocal images of double-labeling with RAGE and HT7 in the hippocampus and cortex (CTX) in aged non-Tg control (a, d) and 3xTg-AD (b, e) mice. Immunoreactivity of HT7, a marker of human tau protein, was higher in the hippocampal area CA1 of aged 3xTg-AD mice compared with aged non-Tg control (c). HT7 labeling overlapped with RAGE. In aged 3xTg-AD mice, HT7 was expressed in some cortical neurons, CA1 neurons, and some axons of the mossy fiber, whereas the DG and hippocampal area CA3 did not show immunoreactivity for HT7 when compared with aged non-Tg controls (e). Data are means±s.e.m. (adult: n=6; aged: n=10). **P<0.01. Scale bar=100 μm.