**Figure 4.** **Administration of Celastrol alleviated bone loss and MAT accumulation in aged mice.** (**A**) mRNA expression level of PGC-1^{α} in the BM-MSCs determined using qRT-PCR (n = 3 per group). (**B**–**G**) Representative μCT images (**B**) and quantitative μCT analysis of trabecular (**C**–**E**) and cortical (**F**, **G**) bone microarchitecture in the femora of Celastrol-treated mice. n = 6-7 per group. (**H**–**I**) Three-point bending measurement of femur maximum load (**H**) and stiffness (**I**). n = 5 per group. (**J**, **K**) Representative μCT images (**J**) and quantification of the ratio of bone volume to tissue volume (**K**) of L4 vertebrae (Vt. BV/TV). n = 6 per group. (**L**) Representative images of H&E staining (**L**, top) and osteocalcin immunohistochemical staining (**L**, bottom). Scale bars: 100 μm. n = 5 per group. Data are presented as mean ± SD. Statistical significance was determined using analysis of variance (one-way ANOVA). * ^{#}P* < 0.001;