APP and Alzheimer disease: In male AD model mice, gonadectomy was performed to induce androgen depletion, which is verified by significantly reduced seminal vesicle weight (seminal vesicle weight/body weight: 0.6 × 10–3 ± 0.4 × 10–3, a sensitive bioassay of androgen levels; Yamane et al., 1986) and serum T levels (0.1 ± 0 ng/ml), compared with sham-operated APP/PS1 mice (seminal vesicle weight/body weight: 5.1 × 10–3 ± 0.8 × 10–3, serum T levels: 7.4 ± 1.0 ng/ml).